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Mendeliome v1.1884 MYZAP Zornitza Stark changed review comment from: 10 individuals from four unrelated families with bi-allelic variants in this gene with DCM. Supportive zebrafish model. Note the MYZAP and GCOM1 genes are part of the GRINL1A complex transcription unit. Some of the reported variants affect GCOM1 with postulated effect on MYZAP due to read through transcription (two families), and in the rest of the families MYZAP was affected directly.
Sources: Literature; to: 10 individuals from four unrelated families with bi-allelic variants in this gene with DCM. Supportive zebrafish model.

The MYZAP gene is part of the GRINL1A complex transcription unit (CTU), or GCOM1, which also includes the downstream POLR2M gene, or GRINL1A.. Some of the reported variants affect GCOM1 with postulated effect on MYZAP due to read through transcription (two families), and in the rest of the families MYZAP was affected directly.

Transcription from an upstream promoter within the GRINL1A CTU produces 2 types of alternatively spliced transcripts: MYZAP transcripts, also called GRINL1A upstream (GUP) transcripts, which include only exons from the MYZAP gene, and GRINL1A combined (GCOM) transcripts, which include exons from both the MYZAP gene and the downstream POLR2M gene. Transcription of the POLR2M gene initiates at a downstream promoter within the GRINL1A CTU and produces alternatively spliced POLR2M transcripts, also called GRINL1A downstream (GDOWN) transcripts, which include only exons from the POLR2M gene
Sources: Literature
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 v1.1333 DLG2 Elena Savva gene: DLG2 was added
gene: DLG2 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: DLG2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: DLG2 were set to PMID: 37860969
Phenotypes for gene: DLG2 were set to Intellectual disability (MONDO#0001071), DLG2-related
Review for gene: DLG2 was set to AMBER
Added comment: PMID: 37860969 - 13 patients from 10 families with neurodevelopmental disorders, dysmorphic features and intragenic deletions including both exonic (minimal affect all transcripts) and UTR regions.
Majority of variants were inherited, some de novo. But many NMD PTCs in gnomAD (some looking messy, in noncanonical transcript etc.)
Sources: Literature
Mendeliome v1.1003 INTS13 Chirag Patel gene: INTS13 was added
gene: INTS13 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: INTS13 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: INTS13 were set to PMID: 36229431
Phenotypes for gene: INTS13 were set to Oral-facial-digital syndrome
Review for gene: INTS13 was set to GREEN
gene: INTS13 was marked as current diagnostic
Added comment: 2 families with 4 affected individuals with Oral-facial-digital (OFD) phenotype. Homozygosity mapping and WES found 2 homozygous variants in INTS13 gene. This is a subunit of the Integrator complex, which associates with RNA Polymerase II and cleaves nascent RNA to modulate gene expression. Variants segregated with disease. Depletion of INTS13 disrupts ciliogenesis in human cultured cells and causes dysregulation of a broad collection of ciliary genes. Knockdown in Xenopus embryos leads to motile cilia anomalies.
Sources: Literature
Mendeliome v1.943 SPTSSA Zornitza Stark Phenotypes for gene: SPTSSA were changed from complex hereditary spastic paraplegia, MONDO:0015150 to Spastic paraplegia 90B, autosomal recessive , MIM# 620417; Spastic paraplegia 90A, autosomal dominant, MIM# 620416
Mendeliome v1.942 SPTSSA Zornitza Stark reviewed gene: SPTSSA: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: Spastic paraplegia 90B, autosomal recessive , MIM# 620417, Spastic paraplegia 90A, autosomal dominant, MIM# 620416; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Mendeliome v1.908 PRSS8 Lucy Spencer gene: PRSS8 was added
gene: PRSS8 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: PRSS8 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PRSS8 were set to 36715754
Phenotypes for gene: PRSS8 were set to ichthyosis MONDO:0019269, PRSS8-related
Review for gene: PRSS8 was set to AMBER
Added comment: PMID: 36715754
1 family with 3 affected sons with congenital ichthyosis, consanguineous parents. All 3 affected members are homozygous for a canonical splice in PRSS8, quantitative RT-PCR showed a significant reduction in normal PRSS8 transcript.

A second family with 4 affected members (proband and 3 cousins) with ichthyosis (3 also had autism), also consanguineous. Only the proband was tested who is homozygous for a missense in PTSS8. However this patient also had a TAAR1 missense (no disease association, but the paper suggests this could be responsible for the autism phenotype- KO mice have abnormal learning behaviour).
Sources: Literature
Mendeliome v1.695 TEFM Ee Ming Wong gene: TEFM was added
gene: TEFM was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: TEFM was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TEFM were set to 36823193
Phenotypes for gene: TEFM were set to Mitochondrial disease (MONDO#0044970), TEFM-related
Review for gene: TEFM was set to GREEN
gene: TEFM was marked as current diagnostic
Added comment: - Seven TEFM variants (4 missense, 2 fs, 1 in-frame del) in seven individuals across five unrelated families
- Muscle and primary fibroblast from the affected individuals have reduced levels of promoter distal mitochondrial RNA transcripts
- TEFM knockdown in zebrafish embryos resulted in neuromuscular junction abnormalities and abnormal mitochondrial function
Sources: Literature
Mendeliome v1.649 SPTSSA Seb Lunke Marked gene: SPTSSA as ready
Mendeliome v1.649 SPTSSA Seb Lunke Gene: sptssa has been classified as Amber List (Moderate Evidence).
Mendeliome v1.649 SPTSSA Seb Lunke Classified gene: SPTSSA as Amber List (moderate evidence)
Mendeliome v1.649 SPTSSA Seb Lunke Gene: sptssa has been classified as Amber List (Moderate Evidence).
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 v1.576 TRA2B Elena Savva gene: TRA2B was added
gene: TRA2B was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: TRA2B was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: TRA2B were set to PMID: 36549593
Phenotypes for gene: TRA2B were set to Neurodevelopmental disorder, TRA2B-related (MONDO#0700092)
Review for gene: TRA2B was set to GREEN
Added comment: PMID: 36549593
- 12 individuals with ID and dev delay. Additional features include infantile spams 6/12, hypotonia 12/12, dilated brain ventricles 6/12, microcephaly 5/12
- All variants result in the loss of 1/2 transcripts (start-losses or PTCs upstream of a second translation start position). Shorter transcript expression is increased, longer transcript expression is decreased.
- Apparently het mice K/O are normal, but complete K/O cannot develop embryonically.
- DN mechanism suggested
Sources: Literature
Mendeliome v1.343 PTS Zornitza Stark Tag treatable tag was added to gene: PTS.
Mendeliome v0.12922 PTS Zornitza Stark Marked gene: PTS as ready
Mendeliome v0.12922 PTS Zornitza Stark Gene: pts has been classified as Green List (High Evidence).
Mendeliome v0.12922 PTS Zornitza Stark Phenotypes for gene: PTS were changed from to Hyperphenylalaninemia, BH4-deficient, A, MIM# 261640
Mendeliome v0.12921 PTS Zornitza Stark Mode of inheritance for gene: PTS was changed from Unknown to BIALLELIC, autosomal or pseudoautosomal
Mendeliome v0.12920 PTS Zornitza Stark reviewed gene: PTS: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: Hyperphenylalaninemia, BH4-deficient, A, MIM# 261640; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Mendeliome v0.12714 TNNI1 Krithika Murali gene: TNNI1 was added
gene: TNNI1 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: TNNI1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: TNNI1 were set to 34934811
Phenotypes for gene: TNNI1 were set to arthrogryposis; joint contractures
Review for gene: TNNI1 was set to AMBER
Added comment: No OMIM gene disease association reported

PMID 34934811 Nishimori et al report 2 individuals from a Japanese family with joint contractures, elevated CK and a novel heterozygous TNNI1 variant.

The proband was born with clasped thumbs (gestational age not stated) requiring surgical correction at 5 months of age. At age 14 was diagnosed with contractures of the neck, trunk, hip and knee with elevated serum CK (1689 IU/L). No muscle weakness noted. Muscle biopsy showed moth-eaten appearance of type I fibres and electron microscopy showed type 1 fibre Z disk streaming.

Trio exome sequencing identified a paternally heterozygous nonsense TNNI1 variant (c.523A>T p.K175*). The proband's father and paternal grandfather (not genotyped) also have a history of joint contractures with elevated CK.

The affected amino acid residue is in the tropomyosin binding site near the C-terminus and is highly conserved. The variant is absent from gnomAD. rt-PCR products of mRNA from the patient's muscle biopsy showed presence of both mutated and normal transcripts.
Sources: Literature
Mendeliome v0.12430 EPO Bryony Thompson changed review comment from: PMID: 27651169, 29514032, 25985138 - At least 4 families reported with heterozygous variants segregating with erythrocytosis. Mechanism of disease is gain-of-function. Frameshift variants identified (c.32delG, c.19delC) use of an alternative promoter (P2) in intron 1 causing the production of functional transcripts and increased amounts of biologically active EPO compared to controls, and 5’UTR conserved variant (c.‐136G>A) and expected to have a similar mechanism.

PMID: 28283061 - single proband from a consanguineous family with severe anaemia (Diamond-Blackfan anaemia phenotype) reported with a homozygous missense (R150Q) showing a mild reduction in its affinity for the EPO receptor; to: PMID: 27651169, 29514032, 25985138 - At least 4 families reported with heterozygous variants segregating with erythrocytosis. Mechanism of disease is gain-of-function. Frameshift variants identified (c.32delG, c.19delC) use of an alternative promoter (P2) in intron 1 causing the production of functional transcripts and increased amounts of biologically active EPO compared to controls, and 5’UTR conserved variant (c.‐136G>A) expected to have a similar mechanism.

PMID: 28283061 - single proband from a consanguineous family with severe anaemia (Diamond-Blackfan anaemia phenotype) reported with a homozygous missense (R150Q) showing a mild reduction in its affinity for the EPO receptor
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 v0.8600 AP1G1 Danielle Ariti gene: AP1G1 was added
gene: AP1G1 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: AP1G1 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: AP1G1 were set to 34102099
Phenotypes for gene: AP1G1 were set to Neurodevelopmental disorder (NDD); Intellectual Disability; Epilepsy
Mode of pathogenicity for gene: AP1G1 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: AP1G1 was set to GREEN
Added comment: Two bi-allelic homozygous missense variants were found in two distinct families with Italian and Pakistani origins; homozygous missense variants.

Eight de novo heterozygous variants were identified in nine isolated affected individuals from nine families; including five missense, two frameshift, and one intronic variant that disrupts the canonical splice acceptor site.

Knocking out AP1G1 Zebrafish model resulted in severe developmental abnormalities and increased lethality.

All individuals had neurodevelopmental disorder (NDD) including global developmental delay and ID, which varied in severity from mild to severe.
Sources: Literature
Mendeliome v0.8000 PLXNA3 Zornitza Stark gene: PLXNA3 was added
gene: PLXNA3 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: PLXNA3 was set to X-LINKED: hemizygous mutation in males, biallelic mutations in females
Publications for gene: PLXNA3 were set to 33495532
Phenotypes for gene: PLXNA3 were set to Hypogonadotropic hypogonadism
Review for gene: PLXNA3 was set to GREEN
Added comment: Screened 216 patients with Idiopathic hypogonadotropic hypogonadism by exome sequencing. Identified 7 individuals from 5 families with hemizygous PLXNA3 missense variants. In 2 of the kindreds, there was at least one more gene known to be associated with IHH (oligogenecity). Data provided with evidence that PLXNA3, a key component of the SEMA3F holoreceptor complex,31 is expressed by the human GnRH and olfactory/vomeronasal systems. S646P variant showed PLXNA3 localization exclusively in the ER, indicating that the variant S646P disrupts cell surface localization of PLXNA3.
Sources: Literature
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 v0.6171 CLRN2 Paul De Fazio gene: CLRN2 was added
gene: CLRN2 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: CLRN2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CLRN2 were set to 33496845
Phenotypes for gene: CLRN2 were set to Non-syndromic hearing loss
Review for gene: CLRN2 was set to AMBER
gene: CLRN2 was marked as current diagnostic
Added comment: Missense variant segregates with non-syndromic hearing loss in 3 members of a consanguineous family, two from one nuclear family and one from another. The variant was also shown to result in some transcripts being abnormally spliced, resulting in a premature stop codon.

Functional studies in zebrafish and mice show the gene plays an essential role in normal organization and maintenance of the auditory hair bundles, and for hearing function.

Rated Amber due to supporting functional studies in mice.
Sources: Literature
Mendeliome v0.4668 BLOC1S5 Zornitza Stark gene: BLOC1S5 was added
gene: BLOC1S5 was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: BLOC1S5 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: BLOC1S5 were set to 32565547
Phenotypes for gene: BLOC1S5 were set to Hermansky–Pudlak syndrome
Review for gene: BLOC1S5 was set to GREEN
Added comment: 2 unrelated patients with mild oculocutaneous albinism, moderate bleeding diathesis, platelet aggregation deficit, and a dramatically decreased number of platelet dense granules, all signs compatible with HPS. Identified distinct homozygous variants in the BLOC1S5 gene (patient 1: deletion of exons 3 and 4, patient 2: 1-bp deletion in exon 4). Parental segregation confirmatory in patient 1, quantitative PCR analysis confirmatory in patient 2). Functional tests performed on platelets of one patient displayed an absence of the obligate multisubunit complex BLOC-1, showing that the variant disrupts BLOC1S5 function and impairs BLOC-1 assembly. Expression of the patient-derived BLOC1S5 deletion in nonpigmented murine Bloc1s5-/- melan-mu melanocytes failed to rescue pigmentation, the assembly of a functional BLOC-1 complex, and melanosome cargo trafficking, unlike the wild-type allele. Pathogenic variants in the genes encoding three other BLOC-1 subunits (DTNBP1, BLOC1S3, and BLOC1S6) underlie HPS types 7, 8, and 9 respectively.
Sources: Literature
Mendeliome v0.2767 UGDH Zornitza Stark gene: UGDH was added
gene: UGDH was added to Mendeliome. Sources: Literature
Mode of inheritance for gene: UGDH was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: UGDH were set to 32001716
Phenotypes for gene: UGDH were set to Epileptic encephalopathy, early infantile, 84 - MIM #618792
Review for gene: UGDH was set to GREEN
Added comment: 36 individuals with biallelic UGDH pathogenic variants reported. The phenotype corresponded overall to a developmental epileptic encephalopathy with hypotonia, feeding difficulties, severe global DD, moderate or commonly severe ID in all. Hypotonia and motor disorder (incl. spasticity, dystonia, ataxia, chorea, etc) often occurred prior to the onset of seizures. A single individual did not present seizures and 2 sibs had only seizures in the setting of fever. There were no individuals with biallelic pLoF variants identified. Parental/sib studies were all compatible with AR inheritance mode.

UGDH encodes the enzyme UDP-glucose dehydrogenase which converts UDP-glucose to UDP-glucuronate, the latter being a critical component of the glycosaminoglycans, hyaluronan, chondroitin sulfate, and heparan sulfate. Patient fibroblast and biochemical assays suggested a LoF effect of variants leading to impairment of UGDH stability, oligomerization or enzymatic activity (decreased UGDH-catalyzed reduction of NAD+ to NADH / hyaluronic acid production which requires UDP-glucuronate).

Attempts to model the disorder using an already developped zebrafish model (for a hypomorphic LoF allele) were unsuccessful as fish did not exhibit seizures spontaneously or upon induction with PTZ. Modelling of the disorder in vitro using patient-derived cerebral organoids demonstrated smaller organoids due to reduced number of proliferating neural progenitors
Sources: Literature
Mendeliome v0.308 PISD Zornitza Stark commented on gene: PISD: 4 individuals in 2 unrelated but consanguineous families from Portugal and Brazil affected by early-onset retinal degeneration, sensorineural hearing loss, microcephaly, intellectual disability, and skeletal dysplasia with scoliosis and short stature (Liberfarb syndrome). Affected individuals shared a homozygous 10-bp deletion immediately upstream of the last exon of the PISD gene. In HEK293T cells, this variant led to aberrant splicing of PISD transcripts. 1 family with 2 sisters with congenital cataracts, short stature, and white matter changes identified compound heterozygous variants in the PISD gene. Decreased conversion of phosphatidylserine to PE in patient fibroblasts is consistent with impaired phosphatidylserine decarboxylase (PISD) enzyme activity.
Mendeliome v0.0 PTS Zornitza Stark gene: PTS was added
gene: PTS was added to Mendeliome_VCGS. Sources: Expert Review Green,Victorian Clinical Genetics Services
Mode of inheritance for gene: PTS was set to Unknown