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Mendeliome v1.1790 ZNF41 Zornitza Stark gene: ZNF41 was added
gene: ZNF41 was added to Mendeliome. Sources: Expert Review
disputed tags were added to gene: ZNF41.
Mode of inheritance for gene: ZNF41 was set to X-LINKED: hemizygous mutation in males, biallelic mutations in females
Publications for gene: ZNF41 were set to 14628291; 23871722
Phenotypes for gene: ZNF41 were set to non-syndromic X-linked intellectual disability MONDO:0019181
Review for gene: ZNF41 was set to RED
Added comment: DISPUTED by ClinGen.

Shoichet et al. (2003) described a female patient with severe nonsyndromic mental retardation and a de novo balanced translocation t(X;7)(p11.3;q11.21) in whom they cloned the DNA fragment that contained the X chromosomal and the autosomal breakpoint. In silico sequence analysis demonstrated that the ZNF41 gene was disrupted. Expression studies indicated that ZNF41 transcripts were absent in the patient cell line, suggesting that the mental disorder in this patient resulted from loss of functional ZNF41. Screening of patients with mental retardation led to the identification of 2 other ZNF41 mutations that were not found in healthy control individuals. Based on their finding of the mutations in ZNF41 identified by Shoichet et al. (2003) in a total of 7 males in the NHLBI Exome Variant Server, and the additional finding of truncating ZNF41 variants in 1 male and 1 female in that database, Piton et al. (2013) classified the involvement of ZNF41 in mental retardation as highly questionable.
Sources: Expert Review
Mendeliome v1.1778 KCNIP4 Ain Roesley gene: KCNIP4 was added
gene: KCNIP4 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: KCNIP4 was set to Unknown
Publications for gene: KCNIP4 were set to 33826137
Phenotypes for gene: KCNIP4 were set to seizures; epilepsy
Review for gene: KCNIP4 was set to RED
gene: KCNIP4 was marked as current diagnostic
Added comment: single paper describing insertions of L1 retrotransposons in KCNIP4
samples were post-mortem of resected temporal cortex from individuals with idiopathic temporal lobe epilepsy

1x de novo insertion of L1 in KCNIP4 however ddPCR revealed that this did NOT alter KCNIP4 mRNA expression
Sources: Literature
Mendeliome v1.1660 DOCK4 Sangavi Sivagnanasundram gene: DOCK4 was added
gene: DOCK4 was added to Mendeliome. Sources: Other
Mode of inheritance for gene: DOCK4 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: DOCK4 were set to PMID: 38526744
Phenotypes for gene: DOCK4 were set to DOCK4-related neurodevelopmental disorder (MONDO:0060490)
Review for gene: DOCK4 was set to GREEN
Added comment: 7 unrelated individuals reported with heterozygous variants (missense or null variants) in DOCK4. The individuals either had ID or DD between mild and moderate with brain abnormalities. Two of the individuals are reportedly compound heterozygous.

Functional assay neuro-2A Dock4 knockout cells by using the Alt-R CRISPR-Cas9 system utilizing two different guide RNAs (ko1 and ko2) and one nonspecific control guide RNA (C: control). The assay depicted the loss of function mechanism in the presence of either p.Arg853Leu and p.Asp946_Lys1966delinsValSer* (described as 945VS).
Sources: Other
Mendeliome v1.1596 CIAO1 Paul De Fazio changed review comment from: PMID:38196629 (note pre-print) describes 4 unrelated patients with core features of progressive muscle weakness, respiratory insufficiency, joint hyperlaxity, ankle tightness, calf pseudohypertrophy, elevated CK, and larning disabilities/difficulties. 2 patients presented with increased iron deposition in the brain. Age of recognition of myopathic symptoms varied from early childhood to adolescence.

PMID: 38411040 reports 2 unrelated patients. Patient 1 was born with microcephaly and borderline hypertonia, and died at 18 months of respiratory failure from bronchiolitis. Patient 2 presented with failure to thrive, a hyperkinetic movement disorder, and autism before deteriorating in late teens with muscle weakness, recurrent pneuomonia with respiratory insufficiency, and eventually death due to multi-organ failure with carnificating pneumonia, septic cardiomyopathy, and intracranial hemorrhages. Immune deficiency was ruled out.

All variants reported were homozygous or compound heterozygous missense variants, with the exception of one large in-frame deletion of exon 7. Cell line studies showed the variants resulted in reduced protein stability and downstream cellular defects which could be rescued by wild-type CIAO1.
Sources: Literature; to: PMID:38196629 (note pre-print) describes 4 unrelated patients with core features of progressive muscle weakness, respiratory insufficiency, joint hyperlaxity, ankle tightness, calf pseudohypertrophy, elevated CK, and larning disabilities/difficulties. 2 patients presented with increased iron deposition in the brain. Age of recognition of myopathic symptoms varied from early childhood to adolescence. Muscle biopsy showed variation in fiber size and an increase in internalized nuclei, as well as scattered degenerating/regenerating fibers and a mild to minimal increase in endomysial fibrosis. Electron microscopy revealed morphologically abnormal mitochondria.

PMID: 38411040 reports 2 unrelated patients. Patient 1 was born with microcephaly and borderline hypertonia, and died at 18 months of respiratory failure from bronchiolitis. Patient 2 presented with failure to thrive, a hyperkinetic movement disorder, and autism before deteriorating in late teens with muscle weakness, recurrent pneuomonia with respiratory insufficiency, and eventually death due to multi-organ failure with carnificating pneumonia, septic cardiomyopathy, and intracranial hemorrhages. Immune deficiency was ruled out.

All variants reported were homozygous or compound heterozygous missense variants, with the exception of one large in-frame deletion of exon 7. Cell line studies showed the variants resulted in reduced protein stability and downstream cellular defects which could be rescued by wild-type CIAO1.
Mendeliome v1.1596 CIAO1 Paul De Fazio gene: CIAO1 was added
gene: CIAO1 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: CIAO1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CIAO1 were set to 38411040; 38196629
Phenotypes for gene: CIAO1 were set to Neuromuscular disease, CIAO1-related (MONDO:0019056)
Penetrance for gene: CIAO1 were set to unknown
Review for gene: CIAO1 was set to GREEN
gene: CIAO1 was marked as current diagnostic
Added comment: PMID:38196629 (note pre-print) describes 4 unrelated patients with core features of progressive muscle weakness, respiratory insufficiency, joint hyperlaxity, ankle tightness, calf pseudohypertrophy, elevated CK, and larning disabilities/difficulties. 2 patients presented with increased iron deposition in the brain. Age of recognition of myopathic symptoms varied from early childhood to adolescence.

PMID: 38411040 reports 2 unrelated patients. Patient 1 was born with microcephaly and borderline hypertonia, and died at 18 months of respiratory failure from bronchiolitis. Patient 2 presented with failure to thrive, a hyperkinetic movement disorder, and autism before deteriorating in late teens with muscle weakness, recurrent pneuomonia with respiratory insufficiency, and eventually death due to multi-organ failure with carnificating pneumonia, septic cardiomyopathy, and intracranial hemorrhages. Immune deficiency was ruled out.

All variants reported were homozygous or compound heterozygous missense variants, with the exception of one large in-frame deletion of exon 7. Cell line studies showed the variants resulted in reduced protein stability and downstream cellular defects which could be rescued by wild-type CIAO1.
Sources: Literature
Mendeliome v1.1584 RGS6 Seb Lunke gene: RGS6 was added
gene: RGS6 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: RGS6 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: RGS6 were set to 38332109; 25525169
Phenotypes for gene: RGS6 were set to Cataract,MONDO:0005129; intellectual disability, MONDO:0001071; microcephaly, MONDO:0001149
Review for gene: RGS6 was set to RED
Added comment: Original paper from 2015 describes single consanguineous with two siblings affected by cataract, developmental delay, and microcephaly >3SD. A homozygous canonical splice variant predicted to lead to NMD in RGS6 was identified by WGS and linkage (rather than full WGS analysis). The 2024 paper speculates that the phenotype is driven by a change in RGS6 isoform balance rather than LoF using a knock-out mouse model. It is noted that the mice did not have microcephaly, and ID was assessed using social interaction. No mention of cataract in the mice.
Sources: Literature
Mendeliome v1.1509 PRDM6 Elena Savva gene: PRDM6 was added
gene: PRDM6 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: PRDM6 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: PRDM6 were set to 38071433; 27716515; 27181681
Phenotypes for gene: PRDM6 were set to Patent ductus arteriosus 3 MIM#617039
Review for gene: PRDM6 was set to GREEN
Added comment: Gene is established for patent ductus arteriosus. Only missense reported but supported by functional studies suggesting LOF.

PMID: 38071433 - Two families (3 affected, 6 affected) with patent ductus arteriosus with/without additional coarctation of the aorta. Family 1 had a missense, family 2 had a PTC - both regarded as VUSs

Additional papers PMID: 27716515;27181681 describe nonsyndromic patent ductus arteriosus for the first time
Sources: Literature
Mendeliome v1.1457 GTPBP1 Lucy Spencer gene: GTPBP1 was added
gene: GTPBP1 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: GTPBP1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: GTPBP1 were set to 38118446
Phenotypes for gene: GTPBP1 were set to Neurodevelopmental disorder (MONDO#0700092), GTPBP1-related
Review for gene: GTPBP1 was set to GREEN
Added comment: PMID: 38118446- Cohort of individuals with variants in GTPBP2 (which has been previously described) and GTPBP1 (new) who have an identical neurodevelopmental syndrome. 4 homozygous individuals from 3 consanguineous families. 2 families have different NMD-predicted nonsense variants and the third has a missense, all are absent from gnomad v4.

The shared cardinal features of GTPBP1 and 2 related disease are microcephaly, profound neurodevelopmental impairment, and distinctive craniofacial features. Epilepsy was present in 10 of 20 individuals but its not clear if those individuals had GTPBP1 or 2 variants.
Sources: Literature
Mendeliome v1.1401 SEL1L Sarah Pantaleo gene: SEL1L was added
gene: SEL1L was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: SEL1L was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SEL1L were set to PMID: 37943610; PMID: 37943617
Phenotypes for gene: SEL1L were set to Neurodevelopmental disorder, MONDO:0700092, SEL1L-related
Penetrance for gene: SEL1L were set to Complete
Added comment: Wang paper PMID: 37943610

SEL1L protein is involved in the SEL1L-HRD1 endoplasmic reticulum (ER)-associated degradation.

Report two biallelic missense variants in SEL1L in six children from three independent families presenting with developmental delay, intellectual disability, microcephaly, facial dysmorphisms, hypotonia and/or ataxia (termed ERAD-associated neurodevelopment disorder with onset in infancy (ENDI). The variants were hypomorphic and impaired ERAD function.

Identified by WES. Parents heterozygous and asymptomatic. P.(Gly585Asp) in Patient 1, p.(Met528Arg) in Patients 2 and 3 (siblings).

All variants cause substrate accumulation. The extent of substrate accumulation in knockin cells was modest compared to those in knockout cells, pointing to a hypomorphic nature.

They also had a variant in HRD1.



Weis paper PMID: 37943617

Third variant p.(Cys141Tyr), biallelic, causing premature death in five patients from a consanguineous family with early-onset neurodevelopmental disorders and agammaglobulinaemia due to severe SEL1L-HRD1 ERAD dysfunction.

This variant appears to have a more severe outcome, exhibiting B cell depletion and agammaglobulinaemia, causing the most severe dysfunction among all of the variants described by this group so far. They postulate that functionality of SEL1L-HRD1 ERAD is inversely correlated with disease severity in humans.

Their symptoms were dev delay, neurological disorder and agammaglobulinaemia in childhood. Along with severe axial hypotonia, short stature and microcephaly.

“Not a complete loss-of-function variant”.
Sources: Literature
Mendeliome v1.1396 GRIA3 Zornitza Stark edited their review of gene: GRIA3: Added comment: New manuscript describing ~40 individuals with variants in GRIA3, including affected females. Some variants demonstrated to be LoF and others GoF. LoF variants generally caused a milder phenotype.; Changed publications: 32977175, 17989220, 38038360; Changed mode of inheritance: X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Mendeliome v1.1254 CFAP20 Sarah Pantaleo gene: CFAP20 was added
gene: CFAP20 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: CFAP20 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CFAP20 were set to PMID:36329026
Phenotypes for gene: CFAP20 were set to Retinitis pigmentosa (MONDO:0019200)
Review for gene: CFAP20 was set to GREEN
Added comment: CFAP20 is a ciliopathy candidate. Demonstrate in zebrafish that cfap20 is required for motile cilia function, and in C. elegans, CFAP-20 maintains the structural integrity of non-motile cilia inner junctions, influencing sensory-dependent signalling and development.

Human patients and zebrafish with CFAP20 mutations both exhibit retinal dystrophy (retinitis pigments). Hence, CFAP20 functions within a structural./functional hub centred on the inner junction that is shared between motile and non-motile cilia, and is distinct from other ciliopathy-associaetd domains or macromolecular complexes.

Describe 8 individuals from 4 independent families with damaging biallelic variants (homozygous or compound heterozygous) in CFAP20 that segregate with retinal dystrophy. All variants cluster to one side of the protein, with two of the residues directly contacting alpha-tubullin.

Family 1 - consanguineous set of 3 siblings from Sudan, homozygous for CFAP20 c.305G>A; p.Arg102His (they also had a homozygous variant in DYNC1LI2 however CFAP20 was considered the better candidate.
Family 2 - 3 siblings from Spain, 2 with retinal dystrophy, 1 genetically tested and has c.337C>T; p.(Arg113Trp) and c.397delC; p.(Gln133Serfs*5)
Family 3 - single affected family member compound het for c.164+1G>A and c.457A>G; p.(Arg153Gly).
Family 4 - 3 affected siblings with generalised retinopathy and variable neurological deficits with c.164+1G>A and c.257G>A; p.(Tyr86Cys)

For all families, no individuals had signs of polycystic kidney disease; however, not all individuals had kidney imaging. Visual defecit phenotype presented between adolescence and adulthood (17-56 years old).

Used HEK293T cell expression studies to demonstrate a statistically significant decline of mutated CFAP20 protein levels (with the exception of p.Arg102His). To test the specific variants, they used the C.elegans orthologues.
Sources: Literature
Mendeliome v1.1145 FTH1 Bryony Thompson Added comment: Comment on list classification: Article describing the gene-disease association with neuroferritinopathy now published in HGG advances
Mendeliome v1.980 FSD1L Chirag Patel gene: FSD1L was added
gene: FSD1L was added to Mendeliome. Sources: Other
Mode of inheritance for gene: FSD1L was set to BIALLELIC, autosomal or pseudoautosomal
Phenotypes for gene: FSD1L were set to Neurodevelopmental disorder
Review for gene: FSD1L was set to GREEN
gene: FSD1L was marked as current diagnostic
Added comment: ESHG 2023:
8 families with biallelic missense/nonsense variants
Presentation only described 1 family/2 affecteds with DD, ID, spastic paraparesis, epilepsy, corpus callosum hypoplasia, and optic nerve hypoplasia

Functional assays:
-reduced expression of FSD1L in mature neurons (RNA studies)
-very low % mature neurons (neuronal differentiation)
-reduced neuronal migration
Sources: Other
Mendeliome v1.906 NSUN6 Michelle Torres gene: NSUN6 was added
gene: NSUN6 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: NSUN6 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NSUN6 were set to 37226891
Phenotypes for gene: NSUN6 were set to neurodevelopmental disorder MONDO:0700092, NSUN6-related
Review for gene: NSUN6 was set to AMBER
Added comment: Three unrelated consanguineous families with developmental delay, intellectual disability, motor delay, and behavioral anomalies. WES detected homozygous variants:
- p.(Leu9Glufs*3): even though authors say is is predicted to cause NMD, it actually is NMD escape. No further studies were performed. A deceased affected sibling and parents were NOT tested.
- p.(Asp323Asn): Shown to result in a misfolded protein. Methylation assay showed mutant could not catalyze m5C deposition in transcribed tRNACys and tRNAThr substrates in vitro. One of the parents and both unaffected siblings were shown to be carriers.
- p.(Glu441Profs*15): truncation (full protein is 470aa) which would result in loss of residues involved in recognition and methylation. Shown to result in a misfolded protein. Parents were shown carriers.
Sources: Literature
Mendeliome v1.896 CHRM5 Elena Savva gene: CHRM5 was added
gene: CHRM5 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: CHRM5 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CHRM5 were set to 37213061
Phenotypes for gene: CHRM5 were set to Congenital anomaly of kidney and urinary tract, (MONDO:0019719), CHRM5-related
Review for gene: CHRM5 was set to RED
Added comment: PMID: 37213061
- homozygous missense p.(Q184R) in a proband with neurogenic bladder and CAKUT. Additional features were small trabeculated urinary bladder, bilateral severe hydronephrosis, grade V VUR right, chronic kidney disease (stage 4).
- Radioligand binding experiments were inconclusive - the missense variant had no effect on receptor expression or binding affinity.
- ACh binding assay did show a 2-fold increase (borderline significant), but no effect in secondary messenger accumulation.
- Transfected CHO line showed no effect on receptor expression
- Described a mouse K/O as having a bladder overactivity

No hom PTCs in gnomAD
Sources: Literature
Mendeliome v1.834 SLC30A9 Lucy Spencer gene: SLC30A9 was added
gene: SLC30A9 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: SLC30A9 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SLC30A9 were set to 37041080
Phenotypes for gene: SLC30A9 were set to Birk-Landau-Perez syndrome (MIM#617595)
Review for gene: SLC30A9 was set to GREEN
Added comment: PMID:37041080 - 2 families previously reported and this paper describes 4 more with biallelic SLC30A9 variants. Original 2 families: 6 affected members all hom for Ala350del, and 1 affected member chet for 2 frameshifts. 4 families from this paper: 2 families have the same homozygous missense (Gly418Val), family 3 has 4 affected sibs hom for Ala350del, family 4 1 affected chet for a frameshift and a synonymous. So 2 fams homs for Ala350del and 2 fams hom for Gly418Val.
All have Brik-Landau-Perez syndrome: all with ID, movement disorder and dystonia, and many with oculomotor apraxia, renal abnormalitie, ptosis, some had hearing impairment.
Sources: Literature
Mendeliome v1.668 MRPS7 Zornitza Stark edited their review of gene: MRPS7: Added comment: Now second publication (PMID: 36421788) describes sisters with an overlapping phenotype including sensorineural deafness and premature ovarian insufficiency. They both had compound heterozygous (one missense, one nonsense) MRPS7 variants.; Changed rating: AMBER; Changed publications: 25556185, 36421788
Mendeliome v1.648 SPTSSA Seb Lunke gene: SPTSSA was added
gene: SPTSSA was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: SPTSSA was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: SPTSSA were set to 36718090
Phenotypes for gene: SPTSSA were set to complex hereditary spastic paraplegia, MONDO:0015150
Review for gene: SPTSSA was set to AMBER
Added comment: Three unrelated individuals with common neurological features of developmental delay, progressive motor impairment, progressive lower extremity spasticity, and epileptiform activity or seizures. Other additional features varied.

Two of the individuals had the same de-novo missense, Thr51Ile, while the third was homozygous for a late truncating variant, Gln58AlafsTer10. The patient with the hom variant was described as less severe.

Functional studies in fibroblasts showed dysregulation of the sphingolipid (SL) synthesis pathway, showing that both variants impair ORMDL regulation of the pathway leading to various levels of increased SL. Over expression of human SPTSSA was shown to lead to motor development in flies, rescued by expression of ORMDL for WT SPTSSA but not mutant SPTSSA.

The de-novo missense were shown to impact regulation more than the hom truncation, while the truncated region was shown to previously to be important for ORMDL regulation.

Mice with a hom KO of the functional equivalent sptssb had early onset ataxia and died prematurely, with evidence of axonic degeneration.
Sources: Literature
Mendeliome v1.635 MIR145 Lucy Spencer gene: MIR145 was added
gene: MIR145 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: MIR145 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: MIR145 were set to 36649075
Phenotypes for gene: MIR145 were set to multisystemic smooth muscle dysfunction syndrome (MONDO:0013452), MIR145-related
Review for gene: MIR145 was set to RED
Added comment: PMID: 36649075- a patient whose fetal ultrasound revealed polyhydramnios, enlarged abdomenand bladder, and prune belly syndrome. During infancy/childhood profound gastrointestinal dysmotility, cerebrovascular disease, and multiple strokes. Described as a multisystemic smooth muscle dysfunction syndrome. Patient was found to have a de novo SNP in MIR145 NR_029686.1:n.18C>A. The MIR145transcript is processed into two microRNAs, with the variant position at nucleotide 3 of miR-145-5p.

Transfection of an siRNA against mutant miR145-5p induced a notable decrease in the expression of several cytoskeletal proteins including transgelin, calponin, and importantly, smooth muscle actin. Hybridization analysis and miR RNA-seq demonstrated a decrease in expression of miR145-5p in the presence of mutant miR145-5p. RNA-seq showed that the differentially expressed genes were substantially different between patient and control fibroblasts.
Sources: Literature
Mendeliome v1.572 ZMYM3 Belinda Chong gene: ZMYM3 was added
gene: ZMYM3 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: ZMYM3 was set to X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Publications for gene: ZMYM3 were set to 36586412; 24721225
Phenotypes for gene: ZMYM3 were set to Neurodevelopmental disorders (NDDs)
Review for gene: ZMYM3 was set to GREEN
Added comment: PMID: 36586412
Using the MatchMaker Exchange - Described 27 individuals with rare, variation in the ZMYM3. Most individuals were males, 17 of which have a maternally inherited variant; six individuals (4 male, 2 female) with de novo variants.
Overlapping features included developmental delay, intellectual disability, behavioural abnormalities, and a specific facial gestalt in a subset of males.
Variants in almost all individuals are missense, including six that recurrently affect two residues. Four unrelated probands were identified with inherited variation affecting Arg441 (R441W), a site at which variation has been previously seen in NDD-affected siblings (24721225), and two individuals have de novo variation resulting in p.Arg1294Cys (c.3880C>T).
ChIP-seq experiments on one variant, p.Arg1274Trp, indicate dramatically reduced genomic occupancy, supporting a hypomorphic effect.
Sources: Literature
Mendeliome v1.504 FEM1C Paul De Fazio gene: FEM1C was added
gene: FEM1C was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: FEM1C was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: FEM1C were set to 36336956; 28135719; 33398170; 33398168
Phenotypes for gene: FEM1C were set to Neurodevelopmental disorder, FEM1C-related MONDO:0700092
Review for gene: FEM1C was set to GREEN
gene: FEM1C was marked as current diagnostic
Added comment: PMID:36336956 describes a 9-year-old boy with severe DD, lack of speech, pyramidal signs, and limb ataxia who had a de novo missense variant Asp126His in FEM1C ascertained by WES. The equivalent variant introduced into the nematode C.elegans resulted in disabled locomotion caused by synaptic abnormalities and not muscle dysfunction.

An alternate change Asp126Val was reported in the DDD study de novo in a patient with uncharacterised developmental delay (PMID:28135719).

The Asp126 residue (but not either of the variants above specifically) was shown to be functionally important by in vitro studies (PMID:33398170;33398168). The residue is highly conserved and located in a region of missense constraint.

Borderline green, 2 patients and an animal model. Note all evidence points to the Asp126 residue being of specific importance.
Sources: Literature
Mendeliome v1.489 PIGN Zornitza Stark edited their review of gene: PIGN: Added comment: Large cohort study of 21 new and review of 40 previously published cases in PMID 36322149

Biallelic-truncating variants were detected in 16 patients-10 with Fryns syndrome, 1 with MCAHS1, 2 with Fryns syndrome/MCAHS1, and 3 with neurologic phenotype. There was an increased risk of prenatal or neonatal death within this group (6 deaths were in utero or within 2 months of life; 6 pregnancies were terminated). Incidence of polyhydramnios, congenital anomalies (eg, diaphragmatic hernia), and dysmorphism was significantly increased. Biallelic missense or mixed genotype were reported in the remaining 45 cases-32 showed a neurologic phenotype and 12 had MCAHS1. No cases of diaphragmatic hernia or abdominal wall defects were seen in this group except patient 1 in which we found the missense variant p.Ser893Arg to result in functionally null alleles, suggesting the possibility of an undescribed functionally important region in the final exon.; Changed publications: 36322149; Changed phenotypes: Multiple congenital anomalies-hypotonia-seizures syndrome 1, MIM# 614080, MONDO:0013563, Fryns syndrome
Mendeliome v1.332 PTPA Zornitza Stark gene: PTPA was added
gene: PTPA was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: PTPA was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PTPA were set to 36073231
Phenotypes for gene: PTPA were set to Intellectual disability, MONDO: 36073231, PTPA-related
Review for gene: PTPA was set to AMBER
Added comment: Biallelic PTPA pathogenic variants lead to a form of ID with later-onset parkinsonism based on 4 individuals from 2 families in the literature. Affected individuals were homozygous for missense variants demonstrated to result to reduced mRNA and protein levels as well as PP2A complex activation. Drosophila studies support an age-dependent locomotor dysfunction. Variants in other PP2A-complex-related genes also lead to NDDs. Summary provided below.

There is currently no associated phenotype in OMIM, G2P, PanelApp UK or SysID.

Consider inclusion in relevant panels (ID, Parkinsonism/movement disorders, etc) with amber rating pending further reports.

------

Fevga, Tesson et al (2022 - PMID: 36073231) describe the features of 4 individuals, from 2 unrelated families, with biallelic pathogenic PTPA variants.

These presented with normal or delayed early milestones, learning disability and ID (mild to moderate) followed by progressive signs of parkinsonism (at the age of 11 yrs in 2 sibs, 15 yrs in another individual). Motor symptoms were responsive to levodopa and later to deep brain stimulation.

Linkage analysis in one consanguineous family followed by exome revealed homozygosity for a missense PTPA variant (NM_178001:c.893T>G/p.Met298Arg). Exome sequencing in affected subjects from the 2nd family revealed homozygosity for a further missense variant (c.512C>A/p.Ala171Asp). There were no other candidate variants for the phenotype following parental / segregation studies.

Role of the gene:
As the authors discuss, PTPA (or PPP2R4) is ubiquitously expressed in all tissues incl. brain and encodes a phosphotyrosyl phosphatase activator of the dimeric form of protein phosphatase-2A (PP2A). PP2A in turn, is the major Ser/Thr phosphatase in brain targeting a large number of proteins involved in diverse functions. Activation of PP2A is dependent on its methylation, which is negatively regulated by the PP2A-specific methylesterase (PME-1). By binding to PME-1, PTPA counteracts the negative influence of the former on PP2A. Pathogenic variants in genes encoding subunits/regulators of the PP2A complex (e.g. PPP2R1A or PPP2CA) are associated with neurodevelopmental disorders.

Variant studies:
Upon overexpression of wt and both variants in a HEK-293 cell line the authors demonstrated that both variants resulted in significantly reduced mRNA and protein levels (which for Ala171Asp were attributed to increased proteasomal degradation). Both variants were shown to result in impaired PP2A complex activation compared to wt.

Drosophila / animal models:
Pan-neuronal RNAi-mediated knockdown of ptpa in Drosophila resulted in an age-dependent locomotor dysfunction, reversible with L-DOPA treatment.
Previous studies in mice suggest cognitive/electrophysiological impairments upon downregulation of PP2A activity in transgenic mice.
Sources: Literature
Mendeliome v1.291 GATA1 Zornitza Stark edited their review of gene: GATA1: Added comment: PMID 36029112: De novo GATA1 initiation codon variant (c.3G>A) identified in a Diamond-Blackfan Anaemia patient. Functional evidence showed that the variant does not affect the GATA1 mRNA but brings about a shorter GATA1 isoform (GATA1s) and reduced full-length functional GATA1 protein (GATA1fl), thereby contributing to an erythropoietic defect. Four other GATA1 variants (c.2T>C, c.220G>C, c.220delG, c.220+2T>C) found in eight families have been described as DBA phenotype.; Changed publications: 36029112; Changed phenotypes: Thrombocytopaenia, X-linked, with or without dyserythropoietic anaemia, MIM# 300367, Haemolytic anaemia due to elevated adenosine deaminase, MIM# 301083, Anemia, X-linked, with/without neutropenia and/or platelet abnormalities, MIM# 300835, Diamond-Blackfan anemia (MONDO:0015253)
Mendeliome v1.285 TYMS Lucy Spencer gene: TYMS was added
gene: TYMS was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: TYMS was set to Other
Publications for gene: TYMS were set to 35931051
Phenotypes for gene: TYMS were set to Dyskeratosis congenita MONDO:0015780
Review for gene: TYMS was set to RED
Added comment: 8 families with dyskeratosis congenita and heterozygous variants in TYMS. 4 PTCs, 2 missense and 1 splice (2 families had the same frameshift). However in all families 1 unaffected parent was also heterozygous for the same TYSM variant.

The other parent in 3 of these families was then shown to carry a heterozygous variant in ENOSF1 which each affected child was also heterozygous for. ENOSF1 has been shown to modify TYMS expression at the RNA level by acting as an antisense molecule to TYMS. ENOSF1 partially overlaps TYMS on chromosome 18 and is transcribed in the opposite direction to TYMS. This paper is suggesting digenic inheritance.

The TYMS wild type parent from another family was seen to have a TYMSOS variant which was also observed along with the TYMS variant in their 2 affected children.

Immunoblotting showed a stark reduction in TYMS protein level in the cells of affected probands when compared to the parent carrier, wild-type parent, and the controls.

Lymphoblastoid cells from affected probands have severe TYMS deficiency, altered cellular deoxyribonucleotide triphosphate pools, and hypersensitivity to the TYMS-specific inhibitor 5-fluorouracil. These defects in the nucleotide metabolism pathway resulted in genotoxic stress, defective transcription, and abnormal telomere maintenance. Gene-rescue studies in cells from affected probands revealed that post-transcriptional epistatic silencing of TYMS is occurring via elevated ENOSF1.
Sources: Literature
Mendeliome v1.247 ZMYND8 Zornitza Stark gene: ZMYND8 was added
gene: ZMYND8 was added to Mendeliome. Sources: Expert Review
Mode of inheritance for gene: ZMYND8 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: ZMYND8 were set to 35916866; 32530565
Phenotypes for gene: ZMYND8 were set to Neurodevelopmental disorder, MONDO:0700092, ZMYND8-related; Delayed speech and language development; Motor delay; Intellectual disability; Abnormality of cardiovascular system morphology; Hearing abnormality; Abnormality of vision; Abnormality of the face; Seizures
Review for gene: ZMYND8 was set to GREEN
Added comment: Dias et al (2022 - PMID: 35916866) describe the phenotype of 11 unrelated individuals with monoallelic de novo (or suspected de novo) missense (N=9) or truncating (N=2) ZMYND8 variants. One of these subjects was previously reported by Suzuki et al (2020 - PMID: 32530565).

Features included speech delay/language difficulties (9/11), motor delay (9/11), ID (in 10/11 - profound in 1, moderate in 2), CHD (7/11 - PDA, VSD, ASD, pulmonary stenosis, etc), hearing or vision impairment (7/11). Seizures were reported in few (in text 5/11, table 2/11). Variable non-familial facial features were present in (9/11).

As the authors discuss, ZMYND8 encodes a multidomain protein playing a role in transcription regulation, chromatin remodeling, regulation of super enhancers, DNA damage response/tumor suppression.

The protein is broadly expressed in brain and shows highest expression in early development.

Molecular modeling and/or a yeast two-hybrid system were suggestive of disrupted interaction of ZMYND8 with Drebrin (missense variants in PWWP domain) or GATAD2A (variants in MYND domain).

Neuronal Zmynd8 knockdown in Drosophila resulted in deficits in habituation learning.
Sources: Expert Review
Mendeliome v1.28 SPTAN1 Zornitza Stark edited their review of gene: SPTAN1: Added comment: Leveille et al (2019) - 2 patients with HSP with biallelic missense SPTAN1 variants Previously described zebrafish, mouse, and rat animal models of SPTAN1 deficiency, all consistently showing axonal degeneration, fitting the pathological features of HSP in humans. Xie et al (2022) - 1 patient with complicated HSP and homozygous SPTAN1 mutation. Healthy parents and sister all carried the heterozygous mutation. Van de Vondel et al (2022) - 22 patients from 14 families with five novel heterozygous SPTAN1 variants. Presentations ranged from cerebellar ataxia, intellectual disability, epilepsy, and spastic paraplegia. A recurrent missense mutation (p.Arg19Trp) in 15 patients with spastic paraplegia. Through protein modeling they showed that mutated amino acids are located at crucial interlinking positions, interconnecting the three-helix bundle of a spectrin repeat.; Changed publications: 20493457, 22258530, 32811770, 35150594, 34526651, 31515523; Changed phenotypes: Developmental and epileptic encephalopathy 5, MIM# 613477, Hereditary spastic paraplegia MONDO:0019064, SPTAN1-related; Changed mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Mendeliome v0.14651 LRP2 Chirag Patel commented on gene: LRP2: Donnai-Barrow syndrome (DBS) was first described as a distinct disorder characterized by diaphragmatic hernia, exomphalos, absent corpus callosum, myopia, agenesis of the corpus callosum and proteinuria, and sensorineural deafness.

Kantarci et al. (2007) identified biallelic LRP2 mutations in 6 families with Donnai-Barrow syndrome and one family with facio-oculo-acoustico-renal syndrome.
Mendeliome v0.13478 B4GALT1 Zornitza Stark changed review comment from: Intellectual disability is part of CDG, although non-neurological forms of this CDG have been described.
Sources: Expert list; to: At least 3 unrelated families.
Sources: Expert list
Mendeliome v0.13297 PDGFRA Krithika Murali changed review comment from: ?Suitability for Incidentalome versus Mendeliome based on adult age of diagnosis in reported cases.

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Six unrelated families reported with heterozygous germline variants associated with familial GIST and/or inflammatory fibroid polyps - IFP (benign lesions caused by excessive tissue proliferation and inflammatory cell infiltration into the lumen of the GI tract). Note that reported individuals diagnosed as adults. One individual reported with diagnosis of gastric mass/polyps age 22 (in 1977) raising the possibility of pre-symptomatic disease onset in adolescence. Green PanelApp England in the following panels: tumour predisposition - childhood onset; inherited predisposition to GIST; sarcoma cancer susceptibility.

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PMID 34107389 Hodan et al 2021 - report a 35 yo F with jejunal IFP and a heterozygous germline missense PDGFRA variant (c.1664A>G p.Y555C) . The variant segregated with 3 relatives with confirmed IFPs. Two obligate carriers were reported to have had a similar phenotype while at least one obligate male carrier had no reported history of IFPs. This variant was also reported in an unrelated family with multiple IFPs in 2006.

PMID 29486293 Manley et al 2018 - proband is a 50 yo M with multiple ileal intusussceptions and IFPs and GIST. Heterozygous D846V germline variant identified. Variant identified in daughter and 2 siblings. Coarser face, coarser skin, broader hands and feet, unexplained premature loss of teeth requiring dentures in their 40s described in relatives with the variant, no polyps or tumour identified in screened family members. Pdgfra +/K mutant mice recapitulated the human phenotype. Mice with the constitutively activated mutant PDGFRA shown to have diffuse expansion of the gastrointestinal submucosa, which exhibits an increased number of spindled fibroblast-like cells and marked collagen deposition. Mutant mice also develop intestinal polyps morphologically similar to IFPs. The Pdgfra +/K mice also exhibit thickened skin due to excess collagen deposition within the dermis and subcutaneous tissues.

PMID 25975287 Ricci et al 2015 - report a family with het germline P653L PDGFRA missense variant. The proband was a 67 yo M with multiple intra-abdominal GIST and gastric/colonic inflammatory fibroid polyps. Multiple adult relatives (youngest age 31) were diagnosed with IFPs/fibrous tumours with the variant segregating with disease.

PMID: 18670346 Carney et al 2008 and PMID: 17566086 Pasini et al 2007 - heterozygous germline PDGFRA mutation (V561D) in an individual with GIST and multiple polyps, diagnosed initially aged 22 with multiple GIST/polyps. No other relatives available for genotyping and no other significant family history reported.

PMID: 17087943 de Raedt et al 2006 - heterozygous PDGFRA(Y555C) variant reported in a family with multiple relatives affected by IFP, including one death from secondary bowel obstruction age 35.

PMID: 14699510 Chompret et al 2004 - Heterozygous c.2675G>T D846Y germline variant detected in a French family with 5 relatives developing adult-onset GIST, variant segregated with disease.

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Gain of function somatic variants associated with sporadic GIST. Somatic chromosomal rearrangements resulting in PDGFRA and FIP1L1 gene fusion associated with idiopathic hypereosinophilic syndrome.; to: Six unrelated families reported with heterozygous germline variants associated with familial GIST and/or inflammatory fibroid polyps - IFP (benign lesions caused by excessive tissue proliferation and inflammatory cell infiltration into the lumen of the GI tract). Note that reported individuals diagnosed as adults. One individual reported with diagnosis of gastric mass/polyps age 22 (in 1977) raising the possibility of pre-symptomatic disease onset in adolescence. Green PanelApp England in the following panels: tumour predisposition - childhood onset; inherited predisposition to GIST; sarcoma cancer susceptibility.

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PMID 34107389 Hodan et al 2021 - report a 35 yo F with jejunal IFP and a heterozygous germline missense PDGFRA variant (c.1664A>G p.Y555C) . The variant segregated with 3 relatives with confirmed IFPs. Two obligate carriers were reported to have had a similar phenotype while at least one obligate male carrier had no reported history of IFPs. This variant was also reported in an unrelated family with multiple IFPs in 2006.

PMID 29486293 Manley et al 2018 - proband is a 50 yo M with multiple ileal intusussceptions and IFPs and GIST. Heterozygous D846V germline variant identified. Variant identified in daughter and 2 siblings. Coarser face, coarser skin, broader hands and feet, unexplained premature loss of teeth requiring dentures in their 40s described in relatives with the variant, no polyps or tumour identified in screened family members. Pdgfra +/K mutant mice recapitulated the human phenotype. Mice with the constitutively activated mutant PDGFRA shown to have diffuse expansion of the gastrointestinal submucosa, which exhibits an increased number of spindled fibroblast-like cells and marked collagen deposition. Mutant mice also develop intestinal polyps morphologically similar to IFPs. The Pdgfra +/K mice also exhibit thickened skin due to excess collagen deposition within the dermis and subcutaneous tissues.

PMID 25975287 Ricci et al 2015 - report a family with het germline P653L PDGFRA missense variant. The proband was a 67 yo M with multiple intra-abdominal GIST and gastric/colonic inflammatory fibroid polyps. Multiple adult relatives (youngest age 31) were diagnosed with IFPs/fibrous tumours with the variant segregating with disease.

PMID: 18670346 Carney et al 2008 and PMID: 17566086 Pasini et al 2007 - heterozygous germline PDGFRA mutation (V561D) in an individual with GIST and multiple polyps, diagnosed initially aged 22 with multiple GIST/polyps. No other relatives available for genotyping and no other significant family history reported.

PMID: 17087943 de Raedt et al 2006 - heterozygous PDGFRA(Y555C) variant reported in a family with multiple relatives affected by IFP, including one death from secondary bowel obstruction age 35.

PMID: 14699510 Chompret et al 2004 - Heterozygous c.2675G>T D846Y germline variant detected in a French family with 5 relatives developing adult-onset GIST, variant segregated with disease.

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Gain of function somatic variants associated with sporadic GIST. Somatic chromosomal rearrangements resulting in PDGFRA and FIP1L1 gene fusion associated with idiopathic hypereosinophilic syndrome.
Mendeliome v0.12859 SGCD Samantha Ayres edited their review of gene: SGCD: Added comment: Variants identified in multiple cases of cardiomyopathy, however most are too common in the general population to explain the disease.
First described in the literature with potential association to cardiomyopathy in 2000 (Tsubata et al 10974018).
Case-control study by Mazzarotto et al 2020, did not identify enrichment of SGCD in DCM cohort.

Animal models demonstrate mild cardiomyopathy phenotype.

Curated as 'limited' gene-disease association by ClinGen; Changed rating: RED; Changed publications: 10974018, 31983221, 23695275; Changed phenotypes: Cardiomyopathy, dilated, 1L, MIM#606685, dilated cardiomyopathy MONDO:0005021; Changed mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Mendeliome v0.12384 SLC52A2 Zornitza Stark changed review comment from: Generally presents with a range of neuropathies but ataxia described.; to: Well established gene-disease association.
Mendeliome v0.11975 TEAD1 Zornitza Stark changed review comment from: Sveinsson chorioretinal atrophy (SCRA) is characterized by bilateral, well-defined, tongue-shaped strips of atrophic retina and choroid that extend from the optic nerve into the peripheral ocular fundus. The lesions may be evident at birth and usually progress at a variable rate, sometimes leading to central visual loss. Separate small distinct circular atrophic lesions are observed in the peripheral ocular fundus in some patients. Congenital anterior polar cataracts are found in approximately 25% of affected individuals.

The vast majority of reported cases were of Icelandic origin but the characteristic clinical picture of SCRA is also described in patients of non-Icelandic descent. The variant reported in the Icelanding population is (c.1261T>C, p.Tyr421His), another variant at same position c.1261T>A, p.Tyr421Asn also reported in non-Icelandic family.

Functional data supports gene-disease association.; to: Sveinsson chorioretinal atrophy (SCRA) is characterized by bilateral, well-defined, tongue-shaped strips of atrophic retina and choroid that extend from the optic nerve into the peripheral ocular fundus. The lesions may be evident at birth and usually progress at a variable rate, sometimes leading to central visual loss. Separate small distinct circular atrophic lesions are observed in the peripheral ocular fundus in some patients. Congenital anterior polar cataracts are found in approximately 25% of affected individuals.

The vast majority of reported cases were of Icelandic origin but the characteristic clinical picture of SCRA is also described in patients of non-Icelandic descent. The variant reported in the Icelanding population is (c.1261T>C, p.Tyr421His), another variant at same position c.1261T>A, p.Tyr421Asn also reported in non-Icelandic family.

A de novo nonsense variant has also been reported in a case with Aicardi syndrome with infantile spasms, agenesis of the corpus callosum, and chorioretinal lacunae.
Mendeliome v0.11754 ADAMTS10 Zornitza Stark changed review comment from: Mild intellectual disability is described in around 10% of affected individuals.
Sources: Expert list; to: Weill-Marchesani syndrome is a rare connective tissue disorder characterized by short stature, brachydactyly, joint stiffness, eye anomalies, including microspherophakia, ectopia of the lenses, severe myopia, and glaucoma, and, occasionally, heart defects
Sources: Expert list
Mendeliome v0.11537 UBA5 Zornitza Stark changed review comment from: Bi-allelic variants in UBA5 cause a range of neurological phenotypes. Ataxia has been specifically described only in one sibling pair. Multiple individuals reported with a more severe EE/ID phenotype, and non-specific movement disorders.; to: Bi-allelic variants in UBA5 cause a range of neurological phenotypes. Ataxia has been specifically described only in one sibling pair. Multiple individuals reported with a more severe EE/ID phenotype, and non-specific movement disorders.

Also note these two reports of demyelinating peripheral neuropathy: 26872069 pair of sibs with mild ataxia, one with neuropathy; 32179706 five individuals from a consanguineous family presenting in infancy with severe fatal neuropathy. Some functional data. Due to early mortality, uncertain at present whether additional features would have developed.
Mendeliome v0.11320 KCNMA1 Zornitza Stark changed review comment from: Multiple individuals with KCNMA1-related channelopathy described, both mono allelic and bi-allelic disease reported; a variety of neurologic symptoms, including ID; some variants are LoF and some are gain of function, some correlation between mechanism of pathogenicity and phenotype.; to: Multiple individuals with KCNMA1-related channelopathy described, both mono allelic and bi-allelic disease reported; a variety of neurologic symptoms, including ID; some variants are LoF and some are gain of function, some correlation between mechanism of pathogenicity and phenotype.

Liang-Wang syndrome is a polymalformation syndrome with neurological involvement.
Mendeliome v0.11103 HIST1H4D Paul De Fazio gene: HIST1H4D was added
gene: HIST1H4D was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: HIST1H4D was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: HIST1H4D were set to 35202563
Phenotypes for gene: HIST1H4D were set to Neurodevelopmental disorder, HIST1H4D-related MONDO:0700092
Review for gene: HIST1H4D was set to AMBER
gene: HIST1H4D was marked as current diagnostic
Added comment: Single individual described with a de novo missense variant Arg41His (Arg40 in H4 nomenclature). Apart from language delay and moderate ID, phenotypes included facial dysmorphisms and cochlear abnormalities and arhinencephaly on MRI. Hearing was normal. Birth length, OFC, weight were all reduced (-2 to -2.5SD).
A zebrafish model has developmental defects.
Sources: Literature
Mendeliome v0.11071 CHKA Konstantinos Varvagiannis gene: CHKA was added
gene: CHKA was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: CHKA was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CHKA were set to 35202461
Phenotypes for gene: CHKA were set to Abnormal muscle tone; Global developmental delay; Intellectual disability; Seizures; Microcephaly; Abnormality of movement; Abnormality of nervous system morphology; Short stature
Penetrance for gene: CHKA were set to Complete
Review for gene: CHKA was set to GREEN
Added comment: Klöckner (2022 - PMID: 35202461) describe the phenotype of 6 individuals (from 5 unrelated families) harboring biallelic CHKA variants.

Shared features incl. abnormal muscle tone(6/6 - hypertonia or hypotonia, 3/6 each), DD/ID (6/6,severe in 4, severe/profound in 2), epilepsy (6/6 - onset: infancy - 3y2m | epileptic spasms or GS at onset), microcephaly (6/6), movement disorders (3/6 - incl. dyskinesia, rigidity, choreoatetotic movements). 2/5 individuals exhibited MRI abnormalities, notably hypomyelination. Short stature was observed in 4/6.

Eventual previous genetic testing was not discussed.

Exome sequencing (quattro ES for 2 sibs, trio ES for 1 individual, singleton for 3 probands) revealed biallelic CHKA variants in all affected individuals. Sanger sequencing was performed for confirmation and segregation studies.

Other variants (in suppl.) were not deemed to be causative for the neurodevelopmental phenotype.

3 different missense, 1 start-loss and 1 truncating variant were identified, namely (NM_0012772.2):
- c.421C>T/p.(Arg141Trp) [3 hmz subjects from 2 consanguineous families],
- c.580C>T/p.Pro194Ser [1 hmz individual born to consanguineous parents],
- c.2T>C/p.(Met1?) [1 hmz individual born to related parents],
- c.14dup/p.(Cys6Leufs*19) in trans with c.1021T>C/p.(Phe341Leu) in 1 individual.

CHKA encodes choline kinase alpha, an enzyme catalyzing the first step of phospholipid synthesis in the Kennedy pathway. The pathway is involved in de novo synthesis of glycerophospholipids, phosphatidylcholine and phosphatidylethanolamine being the most abundant in eukaryotic membranes.

CHKA with its paralog (CHKB) phosphorylates either choline or ethanolamine to phosphocholine or phosphoethanolamine respectively with conversion of ATP to ADP.

As the authors comment, biallelic pathogenic variants in CHKB cause a NDD with muscular dystrophy, hypotonia, ID, microcephaly and structural mitochondrial anomalies (MIM 602541). [Prominent mitochondrial patterning was observed in a single muscle biopsy available from an individual with biallelic CHKA variants].

Other disorders of the Kennedy pathway (due to biallelic PCYT2, SELENOI, PCYT1A variants) present with overlapping features incl. variable DD/ID (no-severe), microcephaly, seizures, visual impairment etc.

CHKA variants were either absent or observed once in gnomAD, affected highly conserved AAs with multiple in silico predictions in favor of a deleterious effect.

In silico modeling suggests structural effects for several of the missense variants (Arg141Trp, Pro194Ser presumably affect ADP binding, Phe341 lying close to the binding site of phosphocholine).

Each of the missense variants was expressed in yeast cells and W. Blot suggested expression at the expected molecular weight at comparative levels. The 3 aforementioned variants exhibited reduced catalytic activity (20%, 15%, 50% respectively).

NMD is thought to underly the deleterious effect of the frameshift one (not studied).

The start-loss variant is expected to result in significantly impaired expression and protein function as eventual utilization of the next possible start codon - occurring at position 123 - would remove 26% of the protein.

Chka(-/-) is embryonically lethal in mice, suggesting that complete loss is not compatible with life. Reduction of choline kinase activity by 30% in heterozygous mice did not appear to result in behavioral abnormalities although this was not studied in detail (PMID cited: 18029352). Finally, screening of 1566 mouse lines identified 198 genes whose disruption yields neuroanatomical phenotypes, Chka(+/-) mice being among these (PMID cited: 31371714).

There is no associated phenotype in OMIM, Gene2Phenotype or SysID.

Overall this gene can be considered for inclusion in the ID and epilepsy panes with green or amber rating (>3 individuals, >3 variants, variant studies, overlapping phenotype of disorders belonging to the same pathway, etc). Consider also inclusion in the microcephaly panel (where available this seemed to be of postnatal onset).
Sources: Literature
Mendeliome v0.11058 HSF2BP Zornitza Stark edited their review of gene: HSF2BP: Added comment: An additional two patients are described with homozygous missense variants, with supportive in vitro functional assay. PMID: 35174157 Now there are 5 affected patients from three independent families and three different biallelic missense variants associated with the condition.; Changed rating: GREEN; Changed publications: 32845237, 35174157
Mendeliome v0.10564 PRDM13 Zornitza Stark Added comment: Comment when marking as ready: Bi-allelic variants: Recessive disease causing ID and DSD described in three reportedly unrelated families (2 consanguineous), but all are from Malta, and all share the same 13bp deletion spanning an exon-intron boundary. Mouse KO is embryonically lethal, and tissue specific KO failed to replicate many of the patients phenotypes, other than hypoplasia of the cerebellar vermis and hemispheres at P21.
Mendeliome v0.10552 SLC35F1 Ain Roesley gene: SLC35F1 was added
gene: SLC35F1 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: SLC35F1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: SLC35F1 were set to 33821533
Phenotypes for gene: SLC35F1 were set to Rett-like syndrome
Penetrance for gene: SLC35F1 were set to unknown
Review for gene: SLC35F1 was set to RED
gene: SLC35F1 was marked as current diagnostic
Added comment: WES found a de novo heterozygous c.1037T>C; p.(I346T) (absent in gnomad v2 and v3) in a female described to have Rett-like syndrome.

Global developmental delay, generalized tonic andtonic–clonic seizure, never acquired independent walking and developed spastictetraplegia in adulthood and limited speech

no protein functional work was performed
Sources: Literature
Mendeliome v0.10433 SKI Seb Lunke changed review comment from: Well established gene disease association with craniosynostosis, skeletal, and cardiovascular anomalies, high-arched palate, micrognathia. Inguinal or umbilical hernia also described. Most common skeletal manifestations are arachnodactyly, pectus deformity, camptodactyly, scoliosis.

LoF not fully established on only missense described so far. Some functional work suggest potential GoF for TGF beta signalling, but not conclusive. Not enough evidence so far to go against LoF.; to: Well established gene disease association with craniosynostosis, skeletal, and cardiovascular anomalies, high-arched palate, micrognathia. Inguinal or umbilical hernia also described. Most common skeletal manifestations are arachnodactyly, pectus deformity, camptodactyly, scoliosis.

LoF not fully established as only missense described so far. Some functional work suggest potential GoF for TGF beta signalling, but not conclusive. Not enough evidence so far to go against LoF.
Mendeliome v0.10433 SKI Seb Lunke commented on gene: SKI: Well established gene disease association with craniosynostosis, skeletal, and cardiovascular anomalies, high-arched palate, micrognathia. Inguinal or umbilical hernia also described. Most common skeletal manifestations are arachnodactyly, pectus deformity, camptodactyly, scoliosis.

LoF not fully established on only missense described so far. Some functional work suggest potential GoF for TGF beta signalling, but not conclusive. Not enough evidence so far to go against LoF.
Mendeliome v0.10427 TECRL Zornitza Stark gene: TECRL was added
gene: TECRL was added to Mendeliome. Sources: Expert Review
Mode of inheritance for gene: TECRL was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TECRL were set to 17666061; 27861123; 30790670; 33367594
Phenotypes for gene: TECRL were set to Ventricular tachycardia, catecholaminergic polymorphic, 3, MIM# 614021
Review for gene: TECRL was set to GREEN
Added comment: DEFINITIVE by ClinGen
Homozygous or cpd heterozygous pathogenic variants in TECRL have been identified in patients with CPVT in at least 3 families in the literature with functional evidence.
- 17666061 one consanguineous family with 4 affected relatives (siblings or 1stcousins)
- 27861123 consanguineous family with 8 affected relatives (siblings or 1stcousins)
- 30790670 reported in a single family with one child with features of CPVT
-A multi-centre review published in 2020 provided an update on these cases and described two additional CPVT cases (homozygous p.Tyr197Ter nonsense variant and homozygous exon 2 deletion) and a family with three children with sudden cardiac death, where one was homozygous for the c.331+1G>A splice donor variant, PMID 33367594
Sources: Expert Review
Mendeliome v0.10181 ADCY5 Zornitza Stark edited their review of gene: ADCY5: Added comment: Neurodevelopmental disorder with hyperkinetic movements and dyskinesia (NEDHYD) is an autosomal recessive complex neurologic disorder characterized by severe global developmental delay with axial hypotonia, impaired intellectual development, poor overall growth, and abnormal involuntary hyperkinetic movements, including dystonia, myoclonus, spasticity, and orofacial dyskinesia. It is the most severe manifestation of ADCY5-related dyskinetic disorders. Five individuals from 2 families reported.

Autosomal recessive hyperkinetic movement disorder with dyskinesia, myoclonus, chorea, and dystonia-2 (HYDMCD2) is characterized by the onset of abnormal involuntary movements, mainly affecting the limbs and causing walking difficulties, in the first decade. The severity is variable; some patients have orofacial dyskinesia, resulting in speech difficulties, or develop neuropsychiatric features, including anxiety and social withdrawal. Cardiomyopathy has rarely been described and may be a manifestation of the disorder. Eight individuals from 2 families reported.; Changed publications: 22782511, 24700542, 33051786, 32647899, 33704598, 34631954, 28971144, 30975617; Changed phenotypes: Dyskinesia, familial, with facial myokymia, MIM# 606703, MONDO:0011707, Hyperkinetic movement disorder with dyskinesia, myoclonus, chorea, and dystonia-2 (HYDMCD2), MIM#619647, Neurodevelopmental disorder with hyperkinetic movements and dyskinesia (NEDHYD), MIM#619651; Changed mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Mendeliome v0.10019 FOXR1 Paul De Fazio changed review comment from: 1 patient described with a de novo missense variant. Phenotypes include: postnatal microcephaly, progressive brain atrophy, skeletal abnormalities, brain abnormalities, ophthalmic abnormalities, neuromuscular abnornmalities, and dysmorphic features.

In vitro functional evidence is supportive of pathogenicity (variant causes protein instability and abnormal nuclear aggregation).

A mouse knockout has comparable phenotypes, and a severe survival deficit.

Rated amber (1 patient, functional evidence, mouse model).
Sources: Literature; to: 1 patient described with a de novo missense variant. Phenotypes include: postnatal microcephaly, progressive brain atrophy, skeletal abnormalities, brain abnormalities, ophthalmic abnormalities, neuromuscular abnormalities, and dysmorphic features. A variant in ATP1A3 was considered to have contributed to the final phenotype.

In vitro functional evidence is supportive of pathogenicity (variant causes protein instability and abnormal nuclear aggregation).

A mouse knockout has comparable phenotypes, and a severe survival deficit.

Rated amber (1 patient, functional evidence, mouse model).
Sources: Literature
Mendeliome v0.10017 FOXR1 Paul De Fazio gene: FOXR1 was added
gene: FOXR1 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: FOXR1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: FOXR1 were set to 34723967
Phenotypes for gene: FOXR1 were set to Postnatal microcephaly, progressive brain atrophy and global developmental delay
Review for gene: FOXR1 was set to AMBER
gene: FOXR1 was marked as current diagnostic
Added comment: 1 patient described with a de novo missense variant. Phenotypes include: postnatal microcephaly, progressive brain atrophy, skeletal abnormalities, brain abnormalities, ophthalmic abnormalities, neuromuscular abnornmalities, and dysmorphic features.

In vitro functional evidence is supportive of pathogenicity (variant causes protein instability and abnormal nuclear aggregation).

A mouse knockout has comparable phenotypes, and a severe survival deficit.

Rated amber (1 patient, functional evidence, mouse model).
Sources: Literature
Mendeliome v0.9682 BMPER Zornitza Stark commented on gene: BMPER: Perinatal lethal skeletal dysplasia.

The primary skeletal characteristics include small chest, abnormal vertebral segmentation, and posterior rib gaps containing incompletely differentiated mesenchymal tissue. Consistent craniofacial features include ocular hypertelorism, epicanthal folds, depressed nasal bridge with short nose, and low-set ears. The most commonly described extraskeletal finding is nephroblastomatosis with cystic kidneys, but other visceral findings have been described in some cases.

At least 5 unrelated families reported.
Mendeliome v0.9473 KCNJ13 Zornitza Stark changed review comment from: LCA and bi-allelic variants: at least 4 individuals reported. Green.

Single family reported with snowflake vitreoretinal degeneration and mono-allelic variant, supportive functional data. Amber/Red.; to: Variants in KCNJ13 are associated with two retinal disorders; Leber congenital amaurosis (LCA) and snowflake vitreoretinal degeneration (SVD), though individuals with bi-allelic variants and LCA with subsequent fibrovascular proliferation described (PMID 31647904).

LCA and bi-allelic variants: at least 4 individuals reported. Green.

Single family reported with snowflake vitreoretinal degeneration and mono-allelic variant, supportive functional data. Amber/Red.
Mendeliome v0.9383 KCNQ1OT1 Zornitza Stark gene: KCNQ1OT1 was added
gene: KCNQ1OT1 was added to Mendeliome. Sources: Expert Review
Mode of inheritance for gene: KCNQ1OT1 was set to MONOALLELIC, autosomal or pseudoautosomal, maternally imprinted (paternal allele expressed)
Publications for gene: KCNQ1OT1 were set to 22205991; 15372379; 23511928; 30794780; 29377879; 10220444; 32447323; 33177595; 29047350
Phenotypes for gene: KCNQ1OT1 were set to Beckwith-Wiedemann syndrome OMIM:130650; Russell-Silver Syndrome
Review for gene: KCNQ1OT1 was set to AMBER
Added comment: Limited evidence that isolated intragenic variation in KCNQ1OT1 is definitively associated with a phenotype.

KCNQ1OT1 encodes the regulatory antisense non-coding RNA KCNQ1OT1 (KCNQ1 overlapping) and is located within the KCNQ1OT1:TSS DMR (imprinting control region 2; IC2) at 11p15.5. IC2 is located within KCNQ1 intron 10. KCNQ1OT1 is maternally imprinted and paternally expressed. On the paternal chromosome, KCNQ1OT1 is transcribed and represses in cis the flanking imprinted genes, including the growth inhibitor CDKN1C, which is normally transcribed from the maternal allele. In 50% of the BWS patients, loss of methylation (LOM) of IC2 leads to biallelic expression of KCNQ1OT1 and biallelic silencing of CDKN1C (PMID 30635621). Expression is increased in BWS due to IC2 epimutations or paternal UPD.

Single nucleotide variants within KCNQ1OT1 have not been definitively associated with human disease. A heterozygous maternally inherited non-coding variant was identified in an individual with isolated omphalocele. This variant was shown to alter the methylation pattern of the imprinted allele (PMID 29047350).

Eggerman et al (PMID 32447323) described a 132 base pair deletion within KCNQ1OT1 associated with growth retardation in the case of paternal but not maternal transmission. This intragenic deletion did not affect IC2 methylation.

Microdeletions of IC2 involving KCNQ1OT1 on the paternal allele have been identified in a small number of patients with Russell-Silver syndrome. Similarly, microdeletions of IC2 involving KCNQ1OT1 on the maternal allele have been identified in a small number of patients with BWS. These deletions also variably involve KCNQ1 or CDKN1C. LoF in CDKN1C is a known cause of BWS. There is some evidence to suggest that disruption of KCNQ1 prevents maternal methylation at IC2 (PMID 30778172).
Sources: Expert Review
Mendeliome v0.9274 CDH15 Zornitza Stark commented on gene: CDH15: PMID: 19012874 - 4 unrelated patients with missense variants and mild-severe ID. Only two genes checked. All variants are common in gnomAD (>20 hets each) and classified as VUS or likely benign in ClinVar (paper is from 2008, pre-dates gnomAD). Functional studies were performed showing a LOF effect, where cell adhesion was reduced.
However NMD PTCs are present in gnomAD (many >=6 hets each)

PMID: 12052883 - null mouse model were viable, showed no gross developmental defects. In particular, the skeletal musculature appeared essentially normal. In the cerebellum of M-cadherin-lacking mutants, typical contactus adherens junctions were present and similar in size and numbers to the equivalent junctions in wild-type animals. However, the adhesion plaques in the cerebellum of these mutants appeared to contain elevated levels of N-cadherin compared to wild-type animals.

PMID: 28422132 - reviewed microdeletions spanning multiple genes including CDH15, suggests it may contribute to a more severe neurological phenotype, with particular regard to brain malformations.

PMID: 26506440 - speculates low penetrance for PTCs in this gene. Acknowledges variants in ExAC, describes them as benign

Note no P/LP variants in ClinVar
Mendeliome v0.9067 GLIS1 Seb Lunke changed review comment from: Functional studies in KO mice show increased intra-ocular pressure (IOT) caused by defects in the ocular drainage system. IOT is frequently associated with Glaucoma, however mice were not investigated for glaucoma, and no patients described.
Sources: Literature; to: Functional studies in KO mice show increased intra-ocular pressure (IOT) caused by defects in the ocular drainage system. IOT is frequently associated with Glaucoma, however mice were not investigated for glaucoma, and no patients described.

The authors did show dysregulation of GLIS1 in a human cell line study, and performed linkage analysis suggesting an association of the GLIS1 locus with Glaucoma in UK biobank samples.
Sources: Literature
Mendeliome v0.9067 GLIS1 Seb Lunke gene: GLIS1 was added
gene: GLIS1 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: GLIS1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: GLIS1 were set to 34385434
Phenotypes for gene: GLIS1 were set to Increased ocular pressure
Review for gene: GLIS1 was set to RED
Added comment: Functional studies in KO mice show increased intra-ocular pressure (IOT) caused by defects in the ocular drainage system. IOT is frequently associated with Glaucoma, however mice were not investigated for glaucoma, and no patients described.
Sources: Literature
Mendeliome v0.8824 PLXNA2 Zornitza Stark gene: PLXNA2 was added
gene: PLXNA2 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: PLXNA2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PLXNA2 were set to 34327814
Phenotypes for gene: PLXNA2 were set to Intellectual disability; Abnormality of the face; Failure to thrive; Abnormal heart morphology
Review for gene: PLXNA2 was set to AMBER
Added comment: Altuame et al (2021 - PMID: 34327814) describe 3 individuals from 2 consanguineous Arab families with biallelic PLXNA2 variants.

The index patient from the 1st family presented with CHD (hypoplastic right ventricle, ASD), DD and moderate ID (IQ of 40), failure to thrive as well as some dysmorphic features (obtuse mandibular angle, mild overbite, synophrys with downslanting p-f, strabismus, etc). There were additional features (eg. postaxial polydactyly) which were found in other affected and unaffected family members.

Exome sequencing with autozygome analysis revealed homozygosity for a PLXNA2 stopgain variant (NM_025179:c.3603C>A / p.(Cys1201*)).

Sanger confirmation was carried out and segregation analyses confirmed carrier status of the unaffected parents and a sib as well as a brother homozygous for the same variant. Clinical evaluation of the latter, following this finding revealed borderline intellectual functioning, ADHD, failure to thrive. There was no mandibular anomaly or overbite and no clinical evidence of CHD (no echo performed).

The index patient from the 2nd consanguineous family was evaluated for ID (IQ of 63), with previous borderline motor development, ADHD and some dysmorphic features (obtuse mandibular angle and overbite). There was no clinical evidence of CHD (no echo performed).

Exome sequencing with autozygosity mapping revealed a homozygous missense PLXNA2 variant (c.3073G>A / p.(Asp1025Asn), present only once in gnomAD (htz), with rather non-concordant in silico predictions SIFT 0.22, PolyPhen 0.682 and CADD 23.5. The aa was however highly conserved.

Segregation analysis confirmed carrier state of the parents and 2 unaffected sibs, with a 3rd sib homozygous for the wt allele.

As the authors discuss:
*PLXNA2 belongs to the plexin family of genes, encoding transmbembrane proteins functioning as semaphorin receptors. It has predominant expression in neural tissue. The protein is thought to bind semaphorin-3A, -3C or -5 followed by plexin A2 dimerization, activation of its GTPase-activating protein domain, negative regulation of Rap1B GTPase and initiation of a signal transduction cascade mediating axonal repulsion/guidance, dendritic guidance, neuronal migration.
*Murine Plxna2 knockout models display structural brain defects. In addition they display congenital heart defects incl. persistent truncus arteriosus and interrupted aortic arch.
*Rare CNVs in adult humans with tetralogy of Fallot have suggested a potential role of PLXNA2 in cardiac development and CHD.
*Expression and the role of PLXNA2 in human chondrocytes as well as a GWAS in 240 japanese patients with mandibular prognathism where PLXNA2 was suggested as a susceptibility locus.

Overall, the authors recognize some common features (as for cognitive functioning, some dysmorphic features incl. obtuse mandibular angle and overbite in 2 unrelated subjects, failure to thrive 3/3) and provide plausible explanations for the variability / discordance of others eg:
- Cyanotic heart disease explaining discordance in cognitive outcome among sibs
- Incomplete penetrance for CHD (and/or ID or mandibular anomaly) as for few AR disorders and/or
- Additional pathogenic variants possibly explaining the CHD in the first subject.

There is no associated phenotype in OMIM or G2P. SysID includes PLXNA2 among the candidate ID genes.
Sources: Literature
Mendeliome v0.8807 VPS50 Zornitza Stark gene: VPS50 was added
gene: VPS50 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: VPS50 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: VPS50 were set to 34037727
Phenotypes for gene: VPS50 were set to Neonatal cholestatic liver disease; Failure to thrive; Profound global developmental delay; Postnatal microcephaly; Seizures; Abnormality of the corpus callosum
Review for gene: VPS50 was set to AMBER
Added comment: Schneeberger et al (2021 - PMID: 34037727) describe the phenotype of 2 unrelated individuals with biallelic VPS50 variants.

Common features included transient neonatal cholestasis, failure to thrive, severe DD with failure to achieve milestones (last examination at 2y and 2y2m respectively), postnatal microcephaly, seizures (onset at 6m and 25m) and irritability. There was corpus callosum hypoplasia on brain imaging.

Both individuals were homozygous for variants private to each family (no/not known consanguinity applying to each case). The first individual was homozygous for a splicing variant (NM_017667.4:c.1978-1G>T) and had a similarly unaffected sister deceased with no available DNA for testing. The other individual was homozygous for an in-frame deletion (c.1823_1825delCAA / p.(Thr608del)).

VPS50 encodes a critical component of the endosome-associated recycling protein (EARP) complex, which functions in recycling endocytic vesicles back to the plasma membrane [OMIM based on Schindler et al]. The complex contains VPS50, VPS51, VPS52, VPS53, the three latter also being components of GARP (Golgi-associated-retrograde protein) complex. GARP contains VPS54 instead of VPS50 and is required for trafficking of proteins to the trans-golgi network. Thus VPS50 (also named syndetin) and VPS54 function in the EARP and GARP complexes, to define directional movement of their endocytic vesicles [OMIM based on Schindler et al]. The VPS50 subunit is required for recycling of the transferrin receptor.

As discussed by Schneeberger et al (refs provided in text):
- VPS50 has a high expression in mouse and human brain as well as throughout mouse brain development.
- Mice deficient for Vps50 have not been reported. vps50 knockdown in zebrafish results in severe developmental defects of the body axis. Knockout mice for other proteins of the EARP/GARP complex (e.g. Vps52, 53 and 54) display embryonic lethality.

Studies performed by Schneeberger et al included:
- Transcript analysis for the 1st variant demonstrated skipping of ex21 (in patient derived fabriblasts) leading to an in frame deletion of 81 bp (r.1978_2058del) with predicted loss of 27 residues (p.Leu660_Leu686del).
- Similar VPS50 mRNA levels but significant reduction of protein levels (~5% and ~8% of controls) were observed in fibroblasts from patients 1 and 2. Additionally, significant reductions in the amounts of VPS52 and VPS53 protein levels were observed despite mRNA levels similar to controls. Overall, this suggested drastic reduction of functional EARP complex levels.
- Lysosomes appeared to have similar morphology, cellular distribution and likely unaffected function in patient fibroblasts.
- Transferrin receptor recycling was shown to be delayed in patient fibroblasts suggestive of compromise of endocytic-recycling function.

As the authors comment, the phenotype of both individuals with biallelic VPS50 variants overlaps with the corresponding phenotype reported in 15 subjects with biallelic VPS53 or VPS51 mutations notably, severe DD/ID, microcephaly and early onset epilepsy, CC anomalies. Overall, for this group, they propose the term "GARP and/or EARP deficiency disorders".

There is no VPS50-associated phenotype in OMIM or G2P. SysID includes VPS50 among the ID candidate genes.
Sources: Literature
Mendeliome v0.8741 TCF7L2 Zornitza Stark changed review comment from: 2 reviews
Konstantinos Varvagiannis (Other)
I don't know

Dias et al (2021 - PMID: 34003604) describe the phenotype of 11 unrelated individuals harboring de novo missense/truncating TCF7L2 variants.

Features included DD in childhood (motor delay in 8/11, speech delay in 11/11), intellectual abilities ranging from average cognitive functioning to mild/moderate ID (the latter observed in 5/11), myopia (6/11) , dysmorphic features, variable orthopedic findings, and neuropsychiatric comorbidities incl. ASD (4/11) / ADHD (4/11).

One additional (12th) individual was excluded from this summary due to concurrent diagnosis of hypoxic-ischemic injury.

TCF7L2 on 10q25 encodes transcription factor 7-like 2, a high mobility group (HMG) box-containing transcription factor. As the authors discuss, the protein mediates canonical Wnt signaling. Secreted Wnt proteins lead to release of beta-catenin (CTNNB1) which after translocation to the nucleus acts with DNA-binding factors incl. TCF7L2 to turn on Wnt-responsive target genes. As a result TCF7L2 acts with beta-catenin as a switch for transcriptional regulation. Multiple alternative spliced TCF7L2 transcripts mediate it's function and specificity of transcriptional repertoire in a variety of tissues and contexts.

Dias et al provide references for its role in nervous system development incl. neurogenesis and thalamic development.

Variants in all cases occurred as de novo events with pLoF (stopgain, frameshift, splicing) ones predicted to lead to NMD. Missense variants occurred in all cases in or adjacent to the HMG box domain [aa 350-417]. 5 different missense variants affecting 3 residues were reported incl. c.1142A>C, c.1143C>G (leading to Asn381Thr/Lys respectively), c.1250G>T (Trp417Leu), c.1267T>C, c.1268A>G (leading to Tyr423His/Cys) [NM_001146274.1].

The gene has a pLI of 0.99-1 gnomAD/ExAC while there is a region of missense constraint encompassing the HMG box domain (the latter is an evolutionary conserved region mediating interactions with DNA).

No phenotypic differences were observed among individuals with pLoF and missense SNVs, and haploinsufficiency is presumed to be the underlying mechanism.

There are no variant or other studies performed, nor any animal models discussed.

In supplementary table 2, the authors provide several references to previous large scale sequencing studies with brief/incomplete descriptions of individuals de novo TCF7L2 variants and neurodevelopmental disorder (ID/ASD - Iossifov, De Rubeis, Lelieveld, McRae/DDD study and many other Refs).

Heterozygous TCF7L2 variants are thought to confer susceptibility to type diabetes mellitus (MIM 125853). Individuals reported by Dias et al did not have endocrine abnormalities including DM. A study by Roychowdhury et al (2021 - PMID: 34265237) suggests that regulatory variants in TCF7L2 are associated with thoracic aneurysm.

There is no other associated phenotype (notably NDD) in OMIM.
G2P includes TCF7L2 in its DD panel (Disease : TC7L2-related DD, Confidence:confirmed, Monoallelic, LoF).
SysID includes this gene within the autism candidate genes and current primary ID genes.; to: Dias et al (2021 - PMID: 34003604) describe the phenotype of 11 unrelated individuals harboring de novo missense/truncating TCF7L2 variants.

Features included DD in childhood (motor delay in 8/11, speech delay in 11/11), intellectual abilities ranging from average cognitive functioning to mild/moderate ID (the latter observed in 5/11), myopia (6/11) , dysmorphic features, variable orthopedic findings, and neuropsychiatric comorbidities incl. ASD (4/11) / ADHD (4/11).

One additional (12th) individual was excluded from this summary due to concurrent diagnosis of hypoxic-ischemic injury.

TCF7L2 on 10q25 encodes transcription factor 7-like 2, a high mobility group (HMG) box-containing transcription factor. As the authors discuss, the protein mediates canonical Wnt signaling. Secreted Wnt proteins lead to release of beta-catenin (CTNNB1) which after translocation to the nucleus acts with DNA-binding factors incl. TCF7L2 to turn on Wnt-responsive target genes. As a result TCF7L2 acts with beta-catenin as a switch for transcriptional regulation. Multiple alternative spliced TCF7L2 transcripts mediate it's function and specificity of transcriptional repertoire in a variety of tissues and contexts.

Dias et al provide references for its role in nervous system development incl. neurogenesis and thalamic development.

Variants in all cases occurred as de novo events with pLoF (stopgain, frameshift, splicing) ones predicted to lead to NMD. Missense variants occurred in all cases in or adjacent to the HMG box domain [aa 350-417]. 5 different missense variants affecting 3 residues were reported incl. c.1142A>C, c.1143C>G (leading to Asn381Thr/Lys respectively), c.1250G>T (Trp417Leu), c.1267T>C, c.1268A>G (leading to Tyr423His/Cys) [NM_001146274.1].

The gene has a pLI of 0.99-1 gnomAD/ExAC while there is a region of missense constraint encompassing the HMG box domain (the latter is an evolutionary conserved region mediating interactions with DNA).

No phenotypic differences were observed among individuals with pLoF and missense SNVs, and haploinsufficiency is presumed to be the underlying mechanism.

There are no variant or other studies performed, nor any animal models discussed.

In supplementary table 2, the authors provide several references to previous large scale sequencing studies with brief/incomplete descriptions of individuals de novo TCF7L2 variants and neurodevelopmental disorder (ID/ASD - Iossifov, De Rubeis, Lelieveld, McRae/DDD study and many other Refs).

Heterozygous TCF7L2 variants are thought to confer susceptibility to type diabetes mellitus (MIM 125853). Individuals reported by Dias et al did not have endocrine abnormalities including DM. A study by Roychowdhury et al (2021 - PMID: 34265237) suggests that regulatory variants in TCF7L2 are associated with thoracic aneurysm.

There is no other associated phenotype (notably NDD) in OMIM.
G2P includes TCF7L2 in its DD panel (Disease : TC7L2-related DD, Confidence:confirmed, Monoallelic, LoF).
SysID includes this gene within the autism candidate genes and current primary ID genes.
Mendeliome v0.8431 SUFU Zornitza Stark changed review comment from: Two unrelated families described with what are postulated to be hypomorphic bi-allelic variants in this gene and Joubert syndrome. Note gene also causes dominant Basal Cell Nevus Syndrome.; to: Two unrelated families described with what are postulated to be hypomorphic bi-allelic variants in this gene and Joubert syndrome.
Mendeliome v0.8335 IMPDH2 Laura Raiti gene: IMPDH2 was added
gene: IMPDH2 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: IMPDH2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: IMPDH2 were set to PMID: 33098801
Phenotypes for gene: IMPDH2 were set to Dystonia
Review for gene: IMPDH2 was set to GREEN
Added comment: 6 unrelated individuals
1x individual in a dystonia cohort index case with infancy-onset dystonia and other neurological manifestations with a de-novo missense variant, c.338G>A (p.Gly113Glu) in IMPDH2, predicted to disrupt an invariant residue within the cystathionine-β-synthase (CBS) domain pair of the encoded protein.
IMPDH2 encodes IMPDH2, a key enzyme in the purine biosynthetic pathway, expressed throughout the brain and not linked previously to any human Mendelian condition.
1x individual with a de-novo substitution, c.337G>A (p.Gly113Arg), was found in in-house whole-exome sequencing data from 500 individuals with neurodevelopmental disorders. Through GeneMatcher, de novo variants identified:
3 x missense: c.729G>C (p.Gln243His), c.619G>C (p.Gly207Arg), and c.619G>A (p.Gly207Arg)
1 x deletion: c.478_480delTCC (p.Ser160del)
The six variants were predicted to be deleterious and none of them seen in control databases. All affected conserved amino acids and resided in and around the cystathionine-β-synthase domain pair.
The described variants are situated in and around the CBS domain pair, a regulatory element in which clustering of pathogenic missense variants has already been shown for the homologue of IMPDH2, IMPDH1.

The variant carriers shared similar neurodevelopmental phenotypes. Apart from the dystonia cohort index case, one participant had evidence of dystonic posturing. Modelling of the variants on 3D protein structures revealed spatial clustering near specific functional sites, predicted to result in deregulation of IMPDH2 activity. Additionally, thermal-shift assays showed that the c.619G>A (p.Gly207Arg) variant, identified as within the CBS domain pair, and c.729G>C (p.Gln243His), which is in close vicinity, affected the stability or folding behaviour of IMPDH2.
Sources: Literature
Mendeliome v0.8217 TCTN3 Zornitza Stark changed review comment from: Rare cause of JBS, I can only find two families reported plus one with OFD. Ataxia specifically described in one of the JBS individuals.; to: Three unrelated families reported with JBTS phenotype. Variants in this gene are associated with other ciliopathies as well (OFD and Mohr-Majewski).
Mendeliome v0.7700 UFSP2 Zornitza Stark changed review comment from: Ni et al (2021 - PMID: 33473208) describe the phenotype of 8 children (belonging to 4 families - 2 of which consanguineous) homozygous for a UFSP2 missense variant [NM_018359.5:c.344T>A; p.(Val115Glu)]. Likely founder variant in all.

Hip dysplasia: single 8 generation family reported.

Spondyloepimetaphyseal dysplasia, Di Rocco type: two families reported.; to: Ni et al (2021 - PMID: 33473208) describe the phenotype of 8 children (belonging to 4 families - 2 of which consanguineous) homozygous for a UFSP2 missense variant [NM_018359.5:c.344T>A; p.(Val115Glu)]. Likely founder variant in all. Additional cases identified through the 100,000 Genomes project.

Hip dysplasia: single 8 generation family reported.

Spondyloepimetaphyseal dysplasia, Di Rocco type: two families reported.
Mendeliome v0.7670 UFSP2 Zornitza Stark changed review comment from: Ni et al (2021 - PMID: 33473208) describe the phenotype of 8 children (belonging to 4 families - 2 of which consanguineous) homozygous for a UFSP2 missense variant [NM_018359.5:c.344T>A; p.(Val115Glu)]. Likely founder variant in all.

Hip dysplasia: single 8 generation family reported.

Spondyloepimetaphyseal dysplasia, Di Rocco type: single 3-generation family reported.; to: Ni et al (2021 - PMID: 33473208) describe the phenotype of 8 children (belonging to 4 families - 2 of which consanguineous) homozygous for a UFSP2 missense variant [NM_018359.5:c.344T>A; p.(Val115Glu)]. Likely founder variant in all.

Hip dysplasia: single 8 generation family reported.

Spondyloepimetaphyseal dysplasia, Di Rocco type: two families reported.
Mendeliome v0.7567 GREB1L Zornitza Stark changed review comment from: At least 16 families described, and mouse model supports gene-disease association.; to: CAKUT: At least 16 families described, and mouse model supports gene-disease association.
Mendeliome v0.7464 VPS41 Kristin Rigbye changed review comment from: "Five unrelated families with nine affected individuals, all carrying homozygous variants in VPS41 that we show impact protein function. All affected individuals presented with a progressive neurodevelopmental disorder consisting of cognitive impairment, cerebellar atrophy/hypoplasia, motor dysfunction with ataxia and dystonia, and nystagmus. Zebrafish disease modelling supports the involvement of VPS41 dysfunction in the disorder, indicating lysosomal dysregulation throughout the brain and providing support for cerebellar and microglial abnormalities when vps41 was mutated. This provides the first example of human disease linked to the HOPS-specific subunit VPS41 and suggests the importance of HOPS complex activity for cerebellar function."; to: "Five unrelated families with nine affected individuals, all carrying homozygous variants in VPS41 that we show impact protein function. All affected individuals presented with a progressive neurodevelopmental disorder consisting of cognitive impairment, cerebellar atrophy/hypoplasia, motor dysfunction with ataxia and dystonia, and nystagmus. Zebrafish disease modelling supports the involvement of VPS41 dysfunction in the disorder, indicating lysosomal dysregulation throughout the brain and providing support for cerebellar and microglial abnormalities when vps41 was mutated. This provides the first example of human disease linked to the HOPS-specific subunit VPS41 and suggests the importance of HOPS complex activity for cerebellar function."

"Affected individuals were born after uneventful pregnancies and presented in most cases early in life with developmental delay. Various degrees of ataxia, hypotonia, and dystonia were present in all affected individuals, preventing independent ambulation. Likewise, nystagmus was commonly described. In addition, all affected individuals displayed intellectual disability and speech delay. Two siblings further presented with therapy-resistant epilepsy. No major dysmorphic features were found. In two individuals, retinal pigment alterations were noticed. Brain MRI revealed mild cerebellar atrophy and vermian atrophy without other major structural abnormalities in most affected individuals while in one case (Subject 9) bilateral hyperintensities at the nucleus caudatus area were noted. No hearing or vision problems were noted and in cases where nerve conduction studies were performed, these were normal. Transmission electron microscopy (TEM) on peripheral blood lymphocytes from Subject 2 and lymphoblastoid cells from Subject 3 revealed more multilayered vesicles compared to control cells."
Mendeliome v0.7191 UNC50 Arina Puzriakova gene: UNC50 was added
gene: UNC50 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: UNC50 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: UNC50 were set to 29016857; 33820833
Phenotypes for gene: UNC50 were set to Arthrogryposis multiplex congenita
Review for gene: UNC50 was set to AMBER
Added comment: UNC50 is currently not associated with any phenotype in OMIM (last edited on 02/01/2018) or Gene2Phenotype.

- PMID: 29016857 (2017) - Homozygosity mapping of disease loci combined with WES in a single male from a consanguineous family presenting with lethal AMC revealed a homozygous frameshift deletion in UNC50 gene (c.750_751del:p.Cys251Phefs*4). Functional studies in C. elegans showed the variant caused loss of acetylcholine receptor expression in the muscle.

- PMID: 33820833 (2021) - Single individual reported with the same homozygous c.750_751del:p.Cys251Phefs*4 variant in UNC50 as previously described. The case was identified from a cohort of 315 genetically undiagnosed and unrelated AMC families. Arthrogryposis and tetra ventricular dilation were detected prenatally.

-- Note: it isn't definitively clear whether these are different individuals. Both are singleton males born to consanguineous parents, with the same variant and similar phenotype. Also both infants died at 28 w.g. However, the 2021 paper (PMID:33820833) states their patient was selected from a cohort of cases without a molecular diagnosis and indicate the UNC50 gene had already previously been identified in relation to this phenotype, highlighting the earlier paper (PMID:29016857). There is also no mention of tetra ventricular dilation in the first case, so it is likely that these do represent distinct individuals. Additional cases needed to provide clarity.
Sources: Literature
Mendeliome v0.6921 TMEM231 Zornitza Stark changed review comment from: Two families described with the Joubert phenotype, severely affected, not ambulant.; to: More than 3 unrelated families reported with each phenotype, functional data.
Mendeliome v0.6846 HDL2 Bryony Thompson STR: HDL2 was added
STR: HDL2 was added to Mendeliome. Sources: Expert list
Mode of inheritance for STR: HDL2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for STR: HDL2 were set to 20301701
Phenotypes for STR: HDL2 were set to Huntington disease-like 2 MIM#606438
Review for STR: HDL2 was set to GREEN
STR: HDL2 was marked as clinically relevant
Added comment: NM_001271604.2:c.431CTG[X] or NM_020655.4:c.382+760CTG[X]
In an alternatively spliced exon, the repeat can be transcribed in both directions, leading to CUG (more common) or CAG (less common) repeat-containing transcripts. While a dominant RNA toxic effect may occur, the repeat expansion also reduces levels of the Junctophilin-3 protein
Normal: ≤28 repeats
Questionable significance: 29-39 repeats, mutable normal or reduced penetrance included
Full penetrance: ≥40 repeats
Sources: Expert list
Mendeliome v0.5549 DNAJB11 Zornitza Stark changed review comment from: Seven unrelated. families described with phenotypes overlapping ADTKD and ADPKD, five different variants, one of these, p.Arg206* recurrent in three families.; to: Seven unrelated. families described with phenotypes overlapping ADTKD and ADPKD, five different mono-allelic variants, one of these, p.Arg206* recurrent in three families.
Mendeliome v0.5270 FOXP4 Zornitza Stark gene: FOXP4 was added
gene: FOXP4 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: FOXP4 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: FOXP4 were set to 33110267
Phenotypes for gene: FOXP4 were set to Neurodevelopmental disorder; multiple congenital abnormalities
Review for gene: FOXP4 was set to GREEN
Added comment: Eight unrelated individuals reported, seven de novo missense, and one individual with a truncating variant. Detailed phenotypic information available on 6. Overlapping features included speech and language delays, growth abnormalities, congenital diaphragmatic hernia (2/6), cervical spine abnormalities, and ptosis. Intellectual disability described as mild in 2, some had normal intellect despite the early speech and language delays.
Sources: Literature
Mendeliome v0.4837 BSND Zornitza Stark changed review comment from: Some individuals with severe Bartter syndrome have been described as having intellectual disability, whereas others with milder symptoms have normal intellect.
Sources: Expert list; to: Well established gene-disease association.
Sources: Expert list
Mendeliome v0.4829 NEK9 Zornitza Stark edited their review of gene: NEK9: Added comment: Another Saudi family described with which 2 sisters and a female cousin who had a similar disorder characterised by arthrogryposis apparent since early childhood, avascular necrosis of the hip (Perthes disease), and upward gaze palsy. Homozygous missense variant segregated with the phenotype. Given the small number of reports, it is unclear whether this represents a distinct association is part of a spectrum with includes the more severe phenotype described in the Irish traveller families.; Changed publications: 26908619, 21271645; Changed phenotypes: Lethal congenital contracture syndrome 10, MIM# 617022, Arthrogryposis, Perthes disease, and upward gaze palsy, MIM# 614262, Skeletal dysplasia
Mendeliome v0.4807 ALG14 Zornitza Stark changed review comment from: 5 individuals from unrelated families described in the literature: one with myasthenic syndrome, no report of ID; second with predominantly ID phenotype; and three more with a neurodegenerative phenotype. ALG14 is part of the UDP-GlcNAc transferase, which catalyzes a key step in endoplasmic reticulum N-linked glycosylation; to: 5 individuals from unrelated families described in the literature: one with myasthenic syndrome, no report of ID; second with predominantly ID phenotype; and three more with a neurodegenerative phenotype. ALG14 is part of the UDP-GlcNAc transferase, which catalyzes a key step in endoplasmic reticulum N-linked glycosylation. The three OMIM disorders may represent a spectrum of severity for CDG.
Mendeliome v0.4783 NUAK2 Seb Lunke gene: NUAK2 was added
gene: NUAK2 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: NUAK2 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: NUAK2 were set to 32845958
Phenotypes for gene: NUAK2 were set to ANENCEPHALY (OMIM#206500)
Review for gene: NUAK2 was set to AMBER
Added comment: Novel gene described in single consanguineous family with three FDIU and extensive anencephaly. Hom inframe del affecting functional kinase domain, parents confirmed carriers. Good functional data showing loss of enzyme function and mouse model with 40% anencephaly after knock-out.
Sources: Literature
Mendeliome v0.4781 MBTPS1 Zornitza Stark gene: MBTPS1 was added
gene: MBTPS1 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: MBTPS1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: MBTPS1 were set to 32857899; 32420688; 30046013
Phenotypes for gene: MBTPS1 were set to Skeletal dysplasia
Review for gene: MBTPS1 was set to GREEN
Added comment: Three unrelated individuals reported with bi-allelic variants in this gene and a skeletal dysplasia, one described with SRS-like features. Elevated blood lysosomal enzymes are also a feature.
Sources: Literature
Mendeliome v0.4770 NEMF Zornitza Stark changed review comment from: Nine individuals from 7 unrelated families reported with a mixed CNS/PNS phenotype. 7/9 had ID, 4/9 had formal assessments demonstrating axonal neuropathy, 3/9 had ataxia; muscular atrophy, hypotonia, respiratory distress, scoliosis also described in some. Three independently generated mouse models had progressive motor neuron degeneration.
Sources: Literature; to: Nine individuals from 7 unrelated families reported with a mixed CNS/PNS phenotype. 7/9 had ID, 4/9 had formal assessments demonstrating axonal neuropathy, 3/9 had ataxia; muscular atrophy, hypotonia, respiratory distress, scoliosis also described in some. Three independently generated mouse models had progressive motor neuron degeneration.

Single individual with de novo variant reported, postulated dominant negative effect. Evidence for mono allelic variants causing disease is limited.
Sources: Literature
Mendeliome v0.4520 SLC12A2 Zornitza Stark edited their review of gene: SLC12A2: Added comment: Monoallelic :
DD/ID was a feature in >= 6 individuals with monoallelic de novo SLC12A2. An individual with an exon 22 truncating variant was reported to have normal milestones and cognitive function. Exon 21 variants have been described in individuals with rather isolated hearing impairment (possibly some associated motor delay, but normal cognition). Hearing impairment was also reported in 2/6 patients with variants in other exons (1 missense / 1 frameshift).

Biallelic :
DD/ID was reported in at least 3 individuals in literature. Hearing impairment has been reported on 2 occasions (although this was not probably evaluated in all subjects).

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Monoallelic SLC12A2 mutations :

► Individuals with de novo mutations and developmental disorder were first identified by the DDD study (2017 - PMID: 28135719). 5 of them have been reported in detail by McNeill et al (below).

► McNeill et al (2020 - PMID: 32658972) report on 6 individuals with neurodevelopmental disorder due to de novo SLC12A2 mutation. All presented DD or ID ranging from mild to severe. ASD was reported in 3/6. Sensorineural hearing loss was a feature in 2/6 with the remaining having normal formal evaluations. Brain, cardiac and/or additional malformations were reported in a single individual. Following non-diagnostic prior work-up (CMA, FMR1 or other investigations) trio exome sequencing revealed missense (4/6) or truncating variants (2/6).

Three additional individuals (incl. a father and his son) with missense variants in exon 21 (NM_001046.3 / p.Glu979Lys and p.Glu980Lys) presented with bilateral sensorineural hearing loss. Speech and/or motor delay reported in these cases were attributed to the hearing impairment/vestibular arreflexia (cognitive abilities not tested).

SLC12A2 encodes sodium-potassium-chloride transporter 1 (also NKCC1).

The GTEx project has identified 8 isoforms. In brain both exon 21-containing/deleted isoforms are expressed (cited Morita et al 2014 - PMID: 24695712). As the authors discuss, RNA-seq of the developing mouse cochlea suggests that the exon 21 containing isoform is the single transcript expressed. Evidence from RNA-seq data (BrainSpan project) and literature suggests that the significant amounts of exon 21 lacking isoforms in fetal brain compensate for the deleterious effects of exon 21 variants and explain the lack of NDD in relevant patients.

Slc12a2 (NKCC1) null mouse model has demonstrated that the transporter plays a role in accumulation of the potassium rich endolymph in the inner ear, with NKCC1 absence causing sensorineural deafness and imbalance. Slc12a2 display cochlear malformations, loss of hair cells and hearing impairment (cited Delpire et al 1999 - PMID: 10369265). The brain phenotype has not been studied extensively, although loss of Slc12a2 has been shown to inhibit neurogenesis (cited: Magalhães and Rivera et al. - PMID: 27582690).

Slc12a2 null zebrafish display a collapse of the otic vesicle and reduced endolymph (Abbas and Whitfield, 2009 - PMID: 19633174) relevant to the human hearing disorder.

In vitro assessment of NKCC1 ion transporter function in Xenopus laevis, supported the deleterious effect of the identified variants (significant reduction in K+ influx). Using available single cell RNA-seq data the authors further demonstrated that SLC12A2 expressing cells display transcriptomic profiles reflective of active neurogenesis.

► Delpire et al (2016 - PMID: 27900370 - not reviewed in detail) described a 13 y.o. girl harboring a de novo 11-bp deletion in SLC12A2 exon 22. This individual reached developmental milestones on time and had a NORMAL cognitive function. Hearing was seemingly normal. Features included orthostatic intolerance, respiratory weakness, multiple endocrine abnormalities, pancreatic insufficiency and multiorgan failure incl. gut and bladder. Exome in the proband, parents and 3 unaffected sibs suggested SLC12A2 as the only candidate for her phenotype. Functional analyses in Xenopus laevis oocytes suggested that a non functional transporter was expressed and trafficked to the membrane as the wt. Detection of the truncated protein at higher molecular sizes suggested either enhanced dimerization or misfolded aggregate. There was no dominant-negative effect of mutant NKCC1. In patient fibroblasts a reduced total and NKCC1-mediated K+ influx.

► Mutai et al (2020 - PMID: 32294086) report on several individuals from 4 families, harboring variants within exon 21 or - in one case - at it's 3' splice-site (leading to skipping oe this exon at the mRNA level). All subjects were investigated for severe/profound hearing loss (in line with the role of exon 21-included isoforms in cochlea. The variant segregated with hearing impairment in 3 generations of a family while in all other subjects the variant had occured as de novo event. Despite motor delays (e.g. the subject from fam2 could not hold head or sit at the age of 10m / the proband in Fam3 was able to hold his head and walk at 6 and 20 m respectively) behavior and cognition were commented to be within normal range.


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Biallelic SLC12A2 mutations:

► Anazi et al (2017 - PMID: 29288388) briefly reported on a 3 y.o. boy (17DG0776) with central hypotonia, neonatal respiratory distress, failure to thrive, global DD and microcephaly and a skeletal survey suggestive of osteopenia. After non-diagnostic prior investigations (CMA revealing a 1p duplication classified as VUS, extensive metabolic workup), WES revealed a homozygous SLC12A2 splicing variant [NM_001046.2:c.2617-2A>G].

► Macnamara et al (2019 - PMID: 30740830) described a 5.5 y.o. male with sensorineural hearing loss, profound delays in all developmental areas among several other features (choanal atresia, failure to thrive, respiratory problems, absent sweat and tear production or salivation, GI abnormalities). Genetic testing for several disorders considered (cystic fibrosis, spinal muscular atrophy, sequencing and del/dup analysis of mtDNA) was normal. CMA revealed paternal uniparental isodisomy for chr. 5 and WGS a homozygous 22kb deletion in SLC12A2. This was followed by confirmation of homozygosity in the proband, heterozygosity of the unaffected father, delineation of breakpoints (chr5:127441491-127471419). mRNA studies in patient fibroblasts confirmed deletion of ex2-7, splicing of ex1 directly to ex8 and introduction of a premature stop codon in ex9. qRT-PCR confirmed that mRNA is likely subjected to NMD (expression ~80% of control). Western blot confirmed absence of the protein in the patient's fibroblasts. Again mouse models are thought to recapitulate the hearing defect but also the deficient saliva production (cited Evans et al 2000 - PMID: 10831596). Again the authors speculate a role of SLC12A2 in brain development based on evidence from murine models (migration, dendritic growth, increse in neuron density through regulation of GABAergic signalling (Young et al 2012 - PMID: 23015452). Hypotheses are also made on a regulatory relationship between NKCC1 and CFTR based on mRNA data from the ko mouse model.

► Stödberg et al (2020 - PMID: 32754646) reported 2 sibs with a complex neurodevelopmental disorder due to compound heterozygosity for a frameshift SLC12A2 variant and a splicing one (NM_001046:c.1431delT and c.2006-1G>A). Both presented hypotonia, neonatal S. aureus parotitis and respiratory problems (incl. apneas). While the older sib died at the age of 22 days, the younger one had persistent respiratory issues incl. a dry respiratory mucosa motivating metabolic, immunology investigations and testing for CF. She displayed microcephaly (OFC -2.5 SD, H was also -3.5SD), severe intellectual disability. MRI was suggestive of white matter and basal ganglia abnormalities. Other features incl. hearing impairment, and lack of tears,saliva and sweat, constipation and intestinal malrotation. There was facial dysmorphism. The variants were the only retained following WGS of the 2 affected sisters, parents and an unaffected brother. The splicing variant was shown to result in skipping of exon 13, while the indel in NMD. Again the authors discuss that the deficient saliva production, impaired hearing and GI problems are recapitulated in the mouse model (several refs provided).; Changed rating: GREEN; Changed publications: 28135719, 32658972, 27900370, 32294086, 29288388, 30740830, 32754646; Changed phenotypes: Kilquist syndrome, deafness, intellectual disability, dysmorphic features, absent salivation, ectodermal dysplasia, constipation, intestinal malrotation, multiple congenital anomalies; Changed mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Mendeliome v0.4497 NEMF Zornitza Stark gene: NEMF was added
gene: NEMF was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: NEMF was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NEMF were set to 32934225
Phenotypes for gene: NEMF were set to Intellectual disability; neuropathy
Review for gene: NEMF was set to GREEN
Added comment: Nine individuals from 7 unrelated families reported with a mixed CNS/PNS phenotype. 7/9 had ID, 4/9 had formal assessments demonstrating axonal neuropathy, 3/9 had ataxia; muscular atrophy, hypotonia, respiratory distress, scoliosis also described in some. Three independently generated mouse models had progressive motor neuron degeneration.
Sources: Literature
Mendeliome v0.4392 SLC25A46 Zornitza Stark changed review comment from: Age of onset is variable, but childhood onset described. Ataxia is a feature.; to: Hereditary motor and sensory neuropathy type VIB is an autosomal recessive complex progressive neurologic disorder characterized mainly by early-onset optic atrophy resulting in progressive visual loss and peripheral axonal sensorimotor neuropathy with highly variable age at onset and severity. Affected individuals also have cerebellar or pontocerebellar atrophy on brain imaging, and they show abnormal movements, such as ataxia, dysmetria, and myoclonus.

At least 10 unrelated families reported, supportive functional data.
Mendeliome v0.4389 MAPK8IP3 Zornitza Stark edited their review of gene: MAPK8IP3: Added comment: 18 unrelated individuals reported with de novo variants and a neurodevelopmental disorder characterised by global developmental delay, variably impaired intellectual development, and poor or absent speech. Additional features may include hypotonia, spasticity, or ataxia. About half have abnormal findings on brain imaging, including cerebral or cerebellar atrophy, loss of white matter volume, thin corpus callosum, and perisylvian polymicrogyria. Seizures are not a prominent finding, and nonspecific dysmorphic facial features are described.; Changed publications: 30612693, 30945334
Mendeliome v0.4275 EXOSC5 Arina Puzriakova changed review comment from: - PMID: 32504085 (2020) - Five patients from four families with biallelic variants in EXCOSC5. Clinical features included short stature (3/5), developmental delays that affect motor skills (3/5), hypotonia (4/5), ataxia (3/4), cerebellar hypoplasia/atrophy (4/5). Cognitive function was generally preserved, but included mild speech delays in one patient.
Cerebellar ataxia was described in two sibs and one singleton - all of whom were compound heterozygous for the p.Thr114Ile variant, inherited in trans with a frameshift variant (p.His30Thrfs*35) or deletion involving exons 5–6 of EXOSC5, respectively.

A LoF zebrafish model resulted in a variety of morphological defects including shortened and curved tails/bodies, reduced eye/head size and oedema. Functional studies of the variants in budding yeast and cultured cells showed some defects in RNA exosome function and interactions, that could not be explained by decrease in the steady-state level of EXOSC5.

- PMID: 29302074 (2019) - Three sibs with a homozygous EXCOSC5 variant (p.Thr114Ile), associated with mild motor delays, cerebellar ataxia, nystagmus, dysarthria, and moderate ID. The family is also described in PMID: 30950035. No functional studies of the variant were undertaken.; to: - PMID: 32504085 (2020) - Five patients from four families with biallelic variants in EXOSC5. Clinical features included short stature (3/5), developmental delays that affect motor skills (3/5), hypotonia (4/5), ataxia (3/4), cerebellar hypoplasia/atrophy (4/5). Cognitive function was generally preserved, but included mild speech delays in one patient.
Cerebellar ataxia was described in two sibs and one singleton - all of whom were compound heterozygous for the p.Thr114Ile variant, inherited in trans with a frameshift variant (p.His30Thrfs*35) or deletion involving exons 5–6 of EXOSC5, respectively.

A LoF zebrafish model resulted in a variety of morphological defects including shortened and curved tails/bodies, reduced eye/head size and oedema. Functional studies of the variants in budding yeast and cultured cells showed some defects in RNA exosome function and interactions, that could not be explained by decrease in the steady-state level of EXOSC5.

- PMID: 29302074 (2019) - Three sibs with a homozygous EXOSC5 variant (p.Thr114Ile), associated with mild motor delays, cerebellar ataxia, nystagmus, dysarthria, and moderate ID. The family is also described in PMID: 30950035. No functional studies of the variant were undertaken.
Mendeliome v0.4257 DNAJC7 Seb Lunke gene: DNAJC7 was added
gene: DNAJC7 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: DNAJC7 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: DNAJC7 were set to 31768050
Phenotypes for gene: DNAJC7 were set to amyotrophic lateral sclerosis
Review for gene: DNAJC7 was set to AMBER
Added comment: Two cohort studies in ALS patients identified 11 and 1 patient, respectively, with variants in DNAJC7. Seven of these are putative PTVs. However gene described as risk factor, unclear why.

DOI: https://doi.org/10.1212/NXG.0000000000000503
Sources: Literature
Mendeliome v0.4226 FDXR Zornitza Stark edited their review of gene: FDXR: Added comment: Four families reported with bi-allelic variants in FDXR causing an autosomal recessive neurologic disorder characterised by onset of visual and hearing impairment in the first or second decades. Two individuals described with a more severe progressive neurological phenotype. Mouse model exhibits neurodegeneration.; Changed rating: GREEN; Changed publications: 30250212, 28965846
Mendeliome v0.4121 UFC1 Paul De Fazio gene: UFC1 was added
gene: UFC1 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: UFC1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: UFC1 were set to 29868776; 30552426
Phenotypes for gene: UFC1 were set to Neurodevelopmental disorder with spasticity and poor growth (MIM#618076)
Review for gene: UFC1 was set to GREEN
gene: UFC1 was marked as current diagnostic
Added comment: PMID 29868776: 8 affected individuals from 4 families reported. 7 were described to be postnatally microcephalic (at or below 3rd percentile). One was -5.1SD and one was -3.6SD. SD values for the others weren't provided.

The following head circumference measurements were provided for 6 of the affecteds:

51cm at 16yo; 50cm at 19yo; 42.5cm at 12mo, 45cm at 28mo, 45.2cm at 7yo; 45cm at 4yo.

3 of the families were consanguineous Saudi families with the same homozygous missense variant.

In vitro functional expression studies showed that both mutations caused impaired thioester binding with UFM1. Patient cells also showed decreased UFC1 intermediate formation with UFM1. The decrease in function was consistent with a hypomorphic allele, and the authors suggested that complete loss of function would be embryonic lethal.

PMID 30552426: 1 more individual with epileptic encephalopathy reported with a different homozygous missense variant in UFC1. The patient had microcephaly <3rd percentile.
Sources: Literature
Mendeliome v0.4091 CTNND1 Eleanor Williams changed review comment from: PMID: 32196547 - Alharatani et al 2020 - report an expanded phenotype for CTNND1 patients. They report 13 individuals from nine families with novel protein-truncating variants in CTNND1 identified by WES. The mutations were not previously described in blepharocheilodontic (BCD), orofacial cleft cases nor in gnomAD. 8 patients had de novo variants, 2 inherited from affected parents, 2 participants inherited a variant from a parent with a mild phenotype. Additional phenotypic features seen include mild limb phenotypes (9/13), cardiovascular anomalies (6/13) and Developmental delay and other neurodevelopmental problems (8/13).; to: PMID: 32196547 - Alharatani et al 2020 - report an expanded phenotype for CTNND1 patients. They report 13 individuals from nine families with novel protein-truncating variants in CTNND1 identified by WES. The mutations were not previously described in blepharocheilodontic (BCD), orofacial cleft cases nor in gnomAD. 8 patients had de novo variants, 2 inherited from affected parents, 2 participants inherited a variant from a parent with a mild phenotype. 8/13 patients showed cleft palate Additional phenotypic features seen include mild limb phenotypes (9/13), cardiovascular anomalies (6/13) and Developmental delay and other neurodevelopmental problems (8/13).
Mendeliome v0.4091 NOTCH3 Eleanor Williams gene: NOTCH3 was added
gene: NOTCH3 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: NOTCH3 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: NOTCH3 were set to 31960911
Phenotypes for gene: NOTCH3 were set to CADASIL
Review for gene: NOTCH3 was set to AMBER
Added comment: PMID: 31960911 - Gravesteijn et al 2020 - describe a family with a unique cysteine-altering NOTCH3 variant in exon 9 in 5 individuals, which is predicted to cause natural exon 9 skipping. This mimics the therapeutic NOTCH3 cysteine correction approach and allows the effect of cysteine corrective exon skipping on NOTCH3 protein aggregation and disease severity in humans to be studied. In this family the CADASIL phenotype was mild.

Note this gene is rated green on the Neurodegenerative disorders - adult onset panel in the Genomics England instance of PanelApp https://panelapp.genomicsengland.co.uk/panels/474/gene/NOTCH3/
Sources: Literature
Mendeliome v0.3872 LMBRD2 Zornitza Stark gene: LMBRD2 was added
gene: LMBRD2 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: LMBRD2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: LMBRD2 were set to 32820033; https://doi.org/10.1101/797787
Phenotypes for gene: LMBRD2 were set to Global developmental delay; Intellectual disability; Microcephaly; Seizures; Abnormality of nervous system morphology; Abnormality of the eye
Mode of pathogenicity for gene: LMBRD2 was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: LMBRD2 was set to GREEN
Added comment: 13 individuals with dn missense SNVs overall, overlapping features for 10 with available phenotype / a recurring variant has been identified in 2 different studies.

► Malhotra et al (2020 - PMID: 32820033) report on 10 unrelated individuals with de novo missense LMBRD2 variants. Features included DD (9/10), ID (6/8 of relevant age), microcephaly (7/10), seizures (5/10 - >=3 different variants), structural brain abnormalities (e.g. thin CC in 6/9), highly variable ocular abnormalities (5/10) and dysmorphic features in some (7/10 - nonspecific). All had variable prior non-diagnostic genetic tests (CMA, gene panel, mendeliome, karyotype). WES/WGS revealed LMBRD2 missense variants, in all cases de novo. A single individual had additional variants with weaker evidence of pathogenicity. 5 unique missense SNVs and 2 recurrent ones (NM_001007527:c.367T>C - p.Trp123Arg / c.1448G>A - p.Arg483His) were identified. These occurred in different exons. Variants were not present in gnomAD and all had several in silico predictions in favor of a deleterious effect. There was phenotypic variability among individuals with the same variant (e.g. seizures in 1/3 and microchephaly in 2/3 of those harboring R483H). The gene has a pLI of 0 (although o/e ranges from 0.23 to 0.55), %HI of 15.13 and z-score of 2.27. The authors presume that haploinsufficiency may not apply, and consider a gain-of-function/dominant-negative effect more likely. As the authors comment LMBRD2 (LMBR1 domain containing 2) encodes a membrane bound protein with poorly described function. It is widely expressed across tissues with notable expression in human brain (also in Drosophila, or Xenopus laevis). It displays high interspecies conservation. It has been suggested (Paek et al - PMID: 28388415) that LMBRD2 is a potential regulator of β2 adrenoreceptor signalling through involvement in GPCR signalling.

► Kaplanis et al (2020 - https://doi.org/10.1101/797787) in a dataset of 31058 parent-offspring trios (WES) previously identified 3 individuals with developmental disorder, harboring c.1448G>A - p.Arg483His. These individuals (1 from the DDD study, and 2 GeneDx patients) appear in Decipher. [ https://decipher.sanger.ac.uk/ddd/research-variant/40e17c78cc9655a6721006fc1e0c98db/overview ]. The preprint by Kaplanis et al is cited by Malhotra et al, with Arg483His reported in 6 patients overall in both studies.
Sources: Literature
Mendeliome v0.3834 TAF1C Zornitza Stark gene: TAF1C was added
gene: TAF1C was added to Mendeliome. Sources: Expert list
Mode of inheritance for gene: TAF1C was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TAF1C were set to 32779182
Phenotypes for gene: TAF1C were set to Global developmental delay; Intellectual disability; Spasticity; Strabismus; Seizures; Abnormality of nervous system morphology
Review for gene: TAF1C was set to AMBER
Added comment: Knuutinen et al (2020 - PMID: 32779182) report on 2 individuals from 2 consanguineous families, homozygous for TAF1C missense variants. Both presented with an early onset neurological phenotype with severe global DD, ID (2/2 - moderate and profound), spasticity (2/2), ophthalmic findings (strabismus 2/2, nystagmus 1/2). Epilepsy, abnormal brain MRI (cerebral and cerebellar atrophy and white matter hyperintensities) as well and additional findings were reported in one (always the same individual). Following a normal CMA, exome in the first case revealed a homozygous missense SNV (NM_005679.3:c.1165C>T / p.Arg389Cys) supported by in silico predictions. mRNA and protein levels were substantially reduced in fibroblasts from this subject. Only the patient and parents were tested for the variant but not 3 unaffected sibs (fig1). The second individual was homozygous for another missense variant (p.Arg405Cys) also supported by in silico predictions. The girl was the single affected person within the family with an unaffected sib and parents heterozygous for the variant. Several other unaffected relatives in the extended pedigree were either carriers for this variant or homozygous for the wt allele. TAF1C encodes the TATA-box binding protein associated factor (TAF) RNA polymerase I subunit. RNA polymerase I (Pol I) transcribes genes to produce rRNA. For Pol I to initiate transcription, two transcription factors are required : UBF (upstream binding factor encoded by UBTF) and SL1 (selectivity factor 1). The latter is formed by TBP (TATA-binding protein) and 3 Pol I-specific TBP-associated factors (TAFs). A recurrent de novo missense variant in UBTF (encoding the other Pol I transcription factor) causes a disorder with highly similar features. The specific variant acts through a gain-of-function mechanism (and not by LoF which appears to apply for TAF1C based on expression data). The authors hypothesize that altered Pol I activity and resulting ribosomal stress could cause the microcephaly and leukodystrophy (both reported in 1 - the same - individual).
Sources: Expert list
Mendeliome v0.3713 HYLS1 Melanie Marty changed review comment from: A recurring homozygous missense variant p.Asp211Gly has been identified in at least 64 cases of hydrolethalus syndrome, described as a Finnish founder mutation (PMID: 15843405, PMID: 18648327). Functional studies in human and patient cells have shown mislocalisation of the protein to the nucleus (PMID: 15843405, PMID: 19400947). Functional studies in c. elegans showed that this variant impaired ciliogenesis (PMID: 19656802). Functional studies in drosophila showed that deletion of HYLS1 led to cilia dysfunction (PMID: 32509774).

2 homozygous living siblings (stop-loss, extension variant p.Ter300TyrextTer11) both diagnosed with Joubert syndrome. Patients had molar tooth signs and dysplasia of cerebellar vermis (PMID: 26830932).

No other variants have been reported as pathogenic in this gene.; to: A recurring homozygous missense variant p.Asp211Gly has been identified in at least 64 cases of hydrolethalus syndrome, described as a Finnish founder mutation (PMID: 15843405, PMID: 18648327). Functional studies in human cells have shown mislocalisation of the protein to the nucleus (PMID: 19400947). Functional studies in c. elegans showed that this variant impaired ciliogenesis (PMID: 19656802). Functional studies in drosophila showed that deletion of HYLS1 led to cilia dysfunction (PMID: 32509774).

2 homozygous living siblings (stop-loss, extension variant p.Ter300TyrextTer11) both diagnosed with Joubert syndrome. Patients had molar tooth signs and dysplasia of cerebellar vermis (PMID: 26830932).

No other variants have been reported as pathogenic in this gene.
Mendeliome v0.3675 PIGQ Zornitza Stark edited their review of gene: PIGQ: Added comment: Homozygous or compound heterozygous mutations in PIGQ cause Epileptic encephalopathy, early infantile, 77 (MIM #618548).

Johnstone et al (2020 - PMID: 32588908) describe the phenotype of 7 children (from 6 families) with biallelic PIGQ pathogenic variants. The authors also review the phenotype of 3 subjects previously reported in the literature (by Martin et al, Alazami et al, Starr et al - respective PMIDs: 24463883, 25558065, 31148362).

Affected individuals displayed severe to profound global DD/ID and seizures with onset in the first year of life. There were variable other features incl. - among others - genitourinary, cardiac, skeletal, ophthalmological anomalies, gastrointestinal issues. Within the cohort there was significant morbidity/mortality.

PIGQ encodes phosphatidylinositol glycan anchor biosynthesis class Q protein, playing a role (early) in the biosynthesis of the GPI-anchor. Several genes in the GPI biosynthesis pathway cause multi-system disease with DD/ID and seizures. Flow cytometry has been used in individuals with PIGQ-related disorder. Serum ALP was elevated in some (4) although - as the authors comment - elevations are more typical in disorders affecting later steps of GPI biosynthesis.

More than 10 variants have been reported to date (missense / pLoF).; Changed phenotypes: Epileptic encephalopathy, early infantile, 77, MIM# 618548
Mendeliome v0.3321 CCDC174 Zornitza Stark gene: CCDC174 was added
gene: CCDC174 was added to Mendeliome. Sources: Expert Review
Mode of inheritance for gene: CCDC174 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CCDC174 were set to 26358778
Phenotypes for gene: CCDC174 were set to Hypotonia, infantile, with psychomotor retardation - IHPMR, 616816
Review for gene: CCDC174 was set to AMBER
Added comment: Biallelic pathogenic CCDC174 variants cause Hypotonia, infantile, with psychomotor retardation - IHPMR (MIM 616816). Volodarsky et al [2015 - PMID: 26358778] describe 6 children from 2 unrelated families with - among others - severe hypotonia, psychomotor delay and abducens nerve palsy. All affected subjects were homozygous for a stoploss variant. Evidence from functional studies/animal model is provided supporting the role of the gene in this phenotype. Overall this gene can be considered for inclusion in the ID panel with amber rating (2 families, single founder variant, consistent phenotype, supportive studies) pending further reports.
Sources: Expert Review
Mendeliome v0.3318 ABCA2 Zornitza Stark gene: ABCA2 was added
gene: ABCA2 was added to Mendeliome. Sources: Expert Review
Mode of inheritance for gene: ABCA2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: ABCA2 were set to 30237576; 29302074; 31047799
Phenotypes for gene: ABCA2 were set to Intellectual developmental disorder with poor growth and with or without seizures or ataxia, 618808
Review for gene: ABCA2 was set to GREEN
Added comment: Biallelic pathogenic ABCA2 variants cause Intellectual developmental disorder with poor growth and with or without seizures or ataxia (MIM 618808). There are 3 relevant publications (01-07-2020) : - Maddirevula et al [2019 - PMID: 30237576] described briefly 2 unrelated subjects (16-2987, 16DG0071) both DD and seizures among other manifestations. - Hu et al [2019 - PMID: 29302074] reported 3 sibs (M8600615 - III:1-3) born to consanguineous parents (M8600615 - III:1-3) with DD/ID (formal confirmation of moderate ID, in those (2) evaluated). One also presented with seizures. - Aslam and Naz [2019 - PMID: 31047799] provided clinical details on 2 siblings born to consanguineous parents. ID was reported for the older sib but was absent in the younger one. Seizures were not part of the phenotype. All subjects harbored biallelic pLoF variants. N.B. : Steinberg et al [2015 - PMID: 25773295], within a cohort of patients with ALS, identified one with biallelic ABCA2 variants. As however Aslam and Naz comment, this person harbored a single pathogenic variant, with a second one rather unlikely to be pathogenic due to high allele frequency. Overall this gene can be considered for inclusion with green rating in both ID and epilepsy panels (each in >=3 unrelated individuals).
Sources: Expert Review
Mendeliome v0.3262 AKR1E2 Zornitza Stark gene: AKR1E2 was added
gene: AKR1E2 was added to Mendeliome. Sources: Expert list
Mode of inheritance for gene: AKR1E2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: AKR1E2 were set to 26622071
Phenotypes for gene: AKR1E2 were set to congenital cataracts
Review for gene: AKR1E2 was set to RED
Added comment: Same family with homozygous canonical splice variants and 3 cases of congenital cataract described in 2012 (original) and 2015 (review). No other descriptions since.
Sources: Expert list
Mendeliome v0.3075 SV2B Seb Lunke gene: SV2B was added
gene: SV2B was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: SV2B was set to Unknown
Publications for gene: SV2B were set to 23617838; 23937191
Phenotypes for gene: SV2B were set to seizures
Review for gene: SV2B was set to RED
Added comment: Multiply described in Epilepsy studies investigating role of SV2 gene family, however no patients directly attributed to variants in this gene and mouse models indicate viability without seizures. Sources: Literature
Sources: Literature
Mendeliome v0.3051 TRIM69 Zornitza Stark gene: TRIM69 was added
gene: TRIM69 was added to Mendeliome. Sources: Expert list
Mode of inheritance for gene: TRIM69 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: TRIM69 were set to 22105173
Phenotypes for gene: TRIM69 were set to Susceptibility to herpes simplex encephalitis
Review for gene: TRIM69 was set to RED
Added comment: One individual with bi-allelic and one individual with mono-allelic variants in this gene described.
Sources: Expert list
Mendeliome v0.2943 CNP Kristin Rigbye gene: CNP was added
gene: CNP was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: CNP was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CNP were set to 32128616; 12590258
Phenotypes for gene: CNP were set to Hypomyelinating leukodystrophy
Review for gene: CNP was set to AMBER
Added comment: Single consanguineous family described with homozygous missense in affected child (additional two affected deceased offspring unavailable for testing; healthy carrier parents and sibling).
Loss of protein by Western blot and defect in F-actin structure and organization observed in patient fibroblasts.
Deficiency of CNP in mouse has previously been shown to cause a lethal white matter neurodegenerative phenotype (PMID: 12590258), similar to the phenotype observed in this family.
Sources: Literature
Mendeliome v0.2842 B9D1 Zornitza Stark changed review comment from: Two unrelated individuals with JS and bi-allelic variants in this gene, plus one individual with a more severe Meckel phenotype described. Intellectual disability is part of the phenotype.
Sources: Expert list; to: Two unrelated individuals with JS and bi-allelic variants in this gene, plus one individual with a more severe Meckel phenotype described. This latter individual had a splice site variant and a deletion. Splice variant proven to result in exon skipping -> PTC, but the deletion spans a large region including 18 other genes. Patient also had an additional variant in CEP290 called LP. Authors perform functional studies on patient cells but given the large deletion/CEP290 variant i dont see the results are usable PMID: 25920555 - another report of digenic inheritance - not usable, patient was only heterozygous for a single B9D1 variant.
Mendeliome v0.2825 PDXK Russell Gear gene: PDXK was added
gene: PDXK was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: PDXK was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PDXK were set to (PMID: 31187503)
Phenotypes for gene: PDXK were set to Axonal polyneuropathy; optic atrophy
Review for gene: PDXK was set to RED
Added comment: Currently two unrelated families with axonal polyneuropathy and optic atrophy described in the same paper, with bi-allelic PDXK pathogenic variants. Functional work in the same paper includes work on patient derived fibroblasts, measurement of an axonal damage biomarker (NFL protein), and response to PLP supplementation treatment.

Need one further unrelated family to upgrade to green?
Sources: Literature
Mendeliome v0.2611 TBL1Y Paul De Fazio changed review comment from: 9 affected males in a single 5-generation pedigree described with Y-linked inheritance pattern. Functional studies show the missense variant causes reduced protein stability. The gene has restricted expression in the cochlea and prostate.
Sources: Literature; to: Y-linked inheritance pattern. Complete segregation of a missense variant demonstrated in 9 affected males in a 5-generation pedigree. Functional studies show the missense variant causes reduced protein stability. The gene has restricted expression in the cochlea and prostate.
Sources: Literature
Mendeliome v0.2611 TBL1Y Paul De Fazio changed review comment from: 9 affected males in a single pedigree described with Y-linked inheritance pattern. Functional studies show the missense variant causes reduced protein stability. The gene has restricted expression in the cochlea and prostate.
Sources: Literature; to: 9 affected males in a single 5-generation pedigree described with Y-linked inheritance pattern. Functional studies show the missense variant causes reduced protein stability. The gene has restricted expression in the cochlea and prostate.
Sources: Literature
Mendeliome v0.2611 TBL1Y Paul De Fazio gene: TBL1Y was added
gene: TBL1Y was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: TBL1Y was set to Other
Publications for gene: TBL1Y were set to 30341416
Phenotypes for gene: TBL1Y were set to Hearing loss
Review for gene: TBL1Y was set to RED
gene: TBL1Y was marked as current diagnostic
Added comment: 9 affected males in a single pedigree described with Y-linked inheritance pattern. Functional studies show the missense variant causes reduced protein stability. The gene has restricted expression in the cochlea and prostate.
Sources: Literature
Mendeliome v0.2440 GFAP Paul De Fazio changed review comment from: Many (>20) de novo individuals described with Alexander disease. Three forms of disease are described with decreasing severity: infant-onset, juveline-onset, and adult-onset. Later-onset cases are more phenotypically heterogeneous.; to: Many (>10) de novo individuals described with Alexander disease. Three forms of disease are described with decreasing severity: infant-onset, juveline-onset, and adult-onset. Later-onset cases are more phenotypically heterogeneous.
Mendeliome v0.2440 GFAP Paul De Fazio changed review comment from: Many (>10) de novo individuals described with Alexander disease. Three forms of disease are described with decreasing severity: infant-onset, juveline-onset, and adult-onset. Later-onset cases are more phenotypically heterogeneous.; to: Many (>20) de novo individuals described with Alexander disease. Three forms of disease are described with decreasing severity: infant-onset, juveline-onset, and adult-onset. Later-onset cases are more phenotypically heterogeneous.
Mendeliome v0.2439 POLR1B Paul De Fazio changed review comment from: 6 individuals with Treacher-Collins syndrome described: 3 with de novo variants, one inherited from a mosaic father, and two inherited from affected mothers. Knockdown in zebrafish mimics the phenotype.
Sources: Literature; to: 6 individuals with Treacher-Collins syndrome described: 3 with de novo variants, one inherited from a mosaic father, and two inherited from affected mothers. Knockdown in zebrafish mimics the phenotype.
Sources: Literature
Mendeliome v0.2439 POLR1B Paul De Fazio gene: POLR1B was added
gene: POLR1B was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: POLR1B was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: POLR1B were set to 31649276
Phenotypes for gene: POLR1B were set to bilateral malar and mandibular hypoplasia; microtia; coloboma; downslanting palpebral fissures; conductive deafness; cleft palate; heart malformations
Review for gene: POLR1B was set to AMBER
gene: POLR1B was marked as current diagnostic
Added comment: 6 individuals with Treacher-Collins syndrome described: 3 with de novo variants, one inherited from a mosaic father, and two inherited from affected mothers. Knockdown in zebrafish mimics the phenotype.
Sources: Literature
Mendeliome v0.2383 GFAP Paul De Fazio changed review comment from: Many (>10) de novo individuals described with Alexander disease. Three forms of disease are described with decreasing severity: infant-onset, juveline-onset, and adult-onset. Later-onset cases are more phenotypically heterogeneous.; to: Many (>10) de novo individuals described with Alexander disease. Three forms of disease are described with decreasing severity: infant-onset, juveline-onset, and adult-onset. Later-onset cases are more phenotypically heterogeneous.
Mendeliome v0.2383 GFAP Paul De Fazio changed review comment from: Many (>10) de novo individuals described with Alexander disease. Three forms of disease are described with decreasing severity: infant-onset, juveline-onset, and adult-onset. Later-onset cases are more phenotypically heterogeneous.; to: Many (>10) de novo individuals described with Alexander disease. Three forms of disease are described with decreasing severity: infant-onset, juveline-onset, and adult-onset. Later-onset cases are more phenotypically heterogeneous.
Mendeliome v0.2013 IL6ST Zornitza Stark changed review comment from: Also known as gp130. Two families with bi-allelic missense variants and immunological phenotype described initially. More recently, five individuals from three families reported with a more complex Stuve-Wiedemann-like phenotype reported, including skeletal dysplasia and neonatal lung dysfunction with additional features such as congenital thrombocytopenia, eczematoid dermatitis, renal abnormalities, and defective acute-phase response. These three families had bi-allelic LoF variants (nonsense and canonical splice site). Several mouse models support gene-disease association.
Sources: Expert list; to: Also known as gp130. Two families with bi-allelic missense variants and immunological phenotype described initially. More recently, five individuals from three families reported with a more complex Stuve-Wiedemann-like phenotype reported, including skeletal dysplasia and neonatal lung dysfunction with additional features such as congenital thrombocytopenia, eczematoid dermatitis, renal abnormalities, and defective acute-phase response. These three families had bi-allelic LoF variants (nonsense and canonical splice site). Several mouse models support gene-disease association.
2020: 12 individuals from 8 unrelated families with seven different mono-allelic truncating variants, dominant negative effect proposed.
Sources: Expert list
Mendeliome v0.1923 IL6ST Zornitza Stark gene: IL6ST was added
gene: IL6ST was added to Mendeliome. Sources: Expert list
Mode of inheritance for gene: IL6ST was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: IL6ST were set to 28747427; 30309848; 12370259; 16041381; 31914175
Phenotypes for gene: IL6ST were set to Hyper-IgE recurrent infection syndrome 4, autosomal recessive, MIM# 618523; Stuve-Wiedemann-like syndrome: skeletal dysplasia, neonatal lung dysfunction, thrombocytopenia, dermatitis, defective acute-phase response.
Review for gene: IL6ST was set to GREEN
Added comment: Also known as gp130. Two families with bi-allelic missense variants and immunological phenotype described initially. More recently, five individuals from three families reported with a more complex Stuve-Wiedemann-like phenotype reported, including skeletal dysplasia and neonatal lung dysfunction with additional features such as congenital thrombocytopenia, eczematoid dermatitis, renal abnormalities, and defective acute-phase response. These three families had bi-allelic LoF variants (nonsense and canonical splice site). Several mouse models support gene-disease association.
Sources: Expert list
Mendeliome v0.1443 ARSG Zornitza Stark gene: ARSG was added
gene: ARSG was added to Mendeliome. Sources: Expert list
Mode of inheritance for gene: ARSG was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: ARSG were set to 29300381; 20679209; 25452429; 26975023
Phenotypes for gene: ARSG were set to Usher syndrome, type IV, MIM# 618144
Review for gene: ARSG was set to RED
Added comment: Atypical late-onset RP/HL phenotype described in 5 individuals from three Yemenite Jewish families. Same homozygous missense variant identified in all, founder effect. Animal models associated with neuronal ceroid lipofuscinosis.
Sources: Expert list
Mendeliome v0.1231 ACTB Sebastian Lunke Added comment: Comment on mode of pathogenicity: Both GoF and LoF described
Mendeliome v0.1007 SCRIB Zornitza Stark Marked gene: SCRIB as ready
Mendeliome v0.1007 SCRIB Zornitza Stark Gene: scrib has been classified as Red List (Low Evidence).
Mendeliome v0.1007 SCRIB Zornitza Stark Publications for gene: SCRIB were set to
Mendeliome v0.797 TET3 Zornitza Stark gene: TET3 was added
gene: TET3 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: TET3 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: TET3 were set to 31928709
Phenotypes for gene: TET3 were set to Intellectual disability; dysmorphic features; abnormal growth; movement disorders
Review for gene: TET3 was set to GREEN
Added comment: Eleven individuals from 8 families described. Mono-allelic frameshift and nonsense variants occur throughout the coding region. Mono-allelic and bi-allelic missense variants localize to conserved residues; all but one such variant occur within the catalytic domain, and most display hypomorphic function in an assay of catalytic activity.
Sources: Literature
Mendeliome v0.677 SETD5 Zornitza Stark Added comment: Comment when marking as ready: PMID: 29484850: Review of all literature reporting SETD5 (table 1). Out of 42 patients described in these papers, 71.4% have motor impairment/delay, 69.0% speech impairment/delay, 23.8% eplilepsy/seizures, 38% congenital heart defects, 95.2% facial dysmorphism, 21.4% hand stereotypies/ritualised behaviour, 19% impaired vision, 42.8% muscle hypotonia and 28.6% polydactyly.
Mendeliome v0.631 KLHL15 Zornitza Stark gene: KLHL15 was added
gene: KLHL15 was added to Mendeliome_VCGS. Sources: Literature
Mode of inheritance for gene: KLHL15 was set to X-LINKED: hemizygous mutation in males, biallelic mutations in females
Publications for gene: KLHL15 were set to 25644381; 24817631
Phenotypes for gene: KLHL15 were set to Mental retardation, X-linked 103, MIM#300982
Review for gene: KLHL15 was set to AMBER
Added comment: Two families described: variants maternally inherited in both, one deletion, the other truncating.
Sources: Literature
Mendeliome v0.551 GLS Zornitza Stark gene: GLS was added
gene: GLS was added to Mendeliome_VCGS. Sources: Expert list
Mode of inheritance for gene: GLS was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: GLS were set to 30575854; 30970188
Phenotypes for gene: GLS were set to Epileptic encephalopathy, early infantile, 71, MIM# 618328; Global developmental delay, progressive ataxia, and elevated glutamine, MIM# 618412
Review for gene: GLS was set to GREEN
Added comment: Three individuals from two unrelated families reported with early neonatal refractory seizures, structural brain abnormalities and oedema; significantly increased glutamine levels (PMID: 30575854).

Another three unrelated individuals described with compound het variants, one of which is a triplet expansion in the 5' UTR (PMID: 30970188).
Sources: Expert list
Mendeliome v0.534 SPATC1L Zornitza Stark gene: SPATC1L was added
gene: SPATC1L was added to Mendeliome_VCGS. Sources: Expert list
Mode of inheritance for gene: SPATC1L was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SPATC1L were set to 30177775
Phenotypes for gene: SPATC1L were set to Deafness
Review for gene: SPATC1L was set to AMBER
Added comment: Two families with compound het variants, and one family with heterozygous variant and dominant pattern of hearing loss described, some functional data.
Sources: Expert list
Mendeliome v0.415 EEF1B2 Zornitza Stark gene: EEF1B2 was added
gene: EEF1B2 was added to Mendeliome_VCGS. Sources: Literature
Mode of inheritance for gene: EEF1B2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: EEF1B2 were set to 31845318; 21937992
Phenotypes for gene: EEF1B2 were set to Intellectual disability
Review for gene: EEF1B2 was set to AMBER
Added comment: 5 individuals from two unrelated families described in the literature so far, no functional data but gene belongs to a family implicated in neurodevelopmental disorders.
Sources: Literature
Mendeliome v0.370 KCNT2 Zornitza Stark gene: KCNT2 was added
gene: KCNT2 was added to Mendeliome_VCGS. Sources: Literature
Mode of inheritance for gene: KCNT2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: KCNT2 were set to 29069600; 29740868
Phenotypes for gene: KCNT2 were set to Epileptic encephalopathy, early infantile, 57, MIM#617771; Developmental and epileptic encephalopathy
Review for gene: KCNT2 was set to GREEN
Added comment: Reviewed by E Palmer: Ambrosino et al described 2 unrelated females with de novo variants in KCNT2. The first patient had the variant p.(Arg190His) had with West syndrome followed by Lennox-Gastaut syndrome , the second patient had the variant p.(Arg190Pro) and DEE with migrating focal seizures. Both variants were absent gnomad and had supportive in silico support for pathogenicity. In an electrophisological model both KCNT2 R190P and KCNT2 R190H increased maximal current density and shifted toward more negative membrane potential values the activation curve of KCNT2 channels, consistent with gain of function effects. PMID: 29740868.

Gururaj et al describe one male with de novo variant in KCNT2 p. (Phe240Leu) and early infantile epileptic encephalopathy. he variant was absent gnomad and supportive evidence of pathogenicity This variant was electrophysiologically modelled and revealed that the variant resulted in a 'change in function' demonstrating unusual altered selectivity in KNa channels.PMID: 29069600.
Sources: Literature
Mendeliome v0.346 SLC12A2 Zornitza Stark gene: SLC12A2 was added
gene: SLC12A2 was added to Mendeliome_VCGS. Sources: Literature
Mode of inheritance for gene: SLC12A2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SLC12A2 were set to 30740830
Phenotypes for gene: SLC12A2 were set to Kilquist syndrome; deafness; intellectual disability; dysmorphic features; absent salivation
Review for gene: SLC12A2 was set to AMBER
Added comment: Single individual with bi-alllelic deletion described; mouse model recapitulated the phenotype.
Sources: Literature
Mendeliome v0.169 CDK16 Zornitza Stark gene: CDK16 was added
gene: CDK16 was added to Mendeliome_VCGS. Sources: Expert list
Mode of inheritance for gene: CDK16 was set to X-LINKED: hemizygous mutation in males, biallelic mutations in females
Publications for gene: CDK16 were set to 25644381
Phenotypes for gene: CDK16 were set to Intellectual disability
Review for gene: CDK16 was set to AMBER
Added comment: Single family described in this manuscript describing multiple candidate genes for XLID.
Sources: Expert list
Mendeliome v0.140 ERMARD Zornitza Stark Added comment: Comment when marking as ready: Single affected individual described in heterozygous missense in this gene; rest of evidence is based on cytogenetic data.
Mendeliome v0.55 SCRIB Zornitza Stark Classified gene: SCRIB as Red List (low evidence)
Mendeliome v0.55 SCRIB Zornitza Stark Gene: scrib has been classified as Red List (Low Evidence).
Mendeliome v0.53 SCRIB Zornitza Stark Marked gene: SCRIB as ready
Mendeliome v0.53 SCRIB Zornitza Stark Gene: scrib has been classified as Green List (High Evidence).
Mendeliome v0.53 SCRIB Zornitza Stark reviewed gene: SCRIB: Rating: RED; Mode of pathogenicity: None; Publications: 24140112, 23922697; Phenotypes: ; Mode of inheritance: None
Mendeliome v0.0 SCRIB Zornitza Stark gene: SCRIB was added
gene: SCRIB was added to Mendeliome_VCGS. Sources: Expert Review Green,Victorian Clinical Genetics Services
Mode of inheritance for gene: SCRIB was set to Unknown