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Intellectual disability syndromic and non-syndromic v0.3102 PRKACB Konstantinos Varvagiannis gene: PRKACB was added
gene: PRKACB was added to Intellectual disability syndromic and non-syndromic. Sources: Literature
Mode of inheritance for gene: PRKACB was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: PRKACB were set to 33058759
Phenotypes for gene: PRKACB were set to Postaxial hand polydactyly; Postaxial foot polydactyly; Common atrium; Atrioventricular canal defect; Narrow chest; Abnormality of the teeth; Intellectual disability
Penetrance for gene: PRKACB were set to Complete
Review for gene: PRKACB was set to AMBER
Added comment: ID was a feature in 2/4 individuals with PRKACB pathogenic variant reported to date.
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Palencia-Campos et al (2020 - PMID: 33058759) report on the phenotype of 3 individuals heterozygous for PRKACA and 4 individuals heterozygous for PRKACB pathogenic variants.

The most characteristic features in all individuals with PRKACA/PRKACB mutation, included postaxial polydactyly of hands (6/7 bilateral, 1/7 unilateral) and feet (4/7 bilateral, 1/7 unilateral), brachydactyly and congenital heart defects (CHD 5/7) namely a common atrium or AVSD. Two individuals with PRKACA variant who did not have CHD had offspring with the same variant and an AVSD.

Other variably occurring features included short stature, limbs, narrow chest, abnormal teeth, oral frenula, nail dysplasia. One individual with PRKACB variant presented tumors.

Intellectual disability was reported in 2/4 individuals with PRKACB variant (1/4: mild, 1/4: severe). The 3 individuals with PRKACA variant did not present ID.

As the phenotype was overall suggestive of Ellis-van Creveld syndrome (or the allelic Weyers acrofacial dysostosis), although these diagnoses were ruled out following analysis of EVC and EVC2 genes.

WES was carried out in all.

PRKACA : A single heterozygous missense variant was identified in 3 individuals from 3 families (NM_002730.4:c.409G>A / p.Gly137Arg) with 1 of the probands harboring the variant in mosaic state (28% of reads) and having 2 similarly affected offspring. The variant was de novo in one individual and inherited in a third one having a similarly affected fetus (narrow thorax, postaxial polyd, AVSD).

PRKACB : 4 different variants were identified (NM_002731.3: p.His88Arg/Asn, p.Gly235Arg, c.161C>T - p.Ser54Leu). One of the individuals was mosaic for the latter variant, while in all other cases the variant had occurred de novo.

Protein kinase A (PKA) is a tetrameric holoenzyme formed by the association of 2 catalytic (C) subunits with a regulatory (R) subunit dimer. Activation of PKA is achieved through binding of 2 cAMP molecules to each R-subunit, and unleashing(/dissociation) of C-subunits to engage substrates. PRKACA/B genes encode the Cα- and Cβ-subunits while the 4 functionally non-redundant regulatory subunits are encoded by PRKAR1A/1B/2A/2B genes.

The authors provide evidence that the variants confer increased sensitivity of PKA holoenzymes to activation by cAMP (compared to wt).

By performing ectopic expression of wt or mt PRKACA/B (variants studied : PRKACA p.Gly137Arg / PRKACB p.Gly235Arg) in NIH 3T3 fibroblasts, the authors demonstrate that inhibition of hedgehog signaling likely underlyies the developmental defects observed in affected individuals.

As for PRKACA, the authors cite another study where a 31-month old female with EvC syndrome diagnosis was found to harbor the aforementioned variant (NM_001304349.1:c.637G>A:p.Gly213Arg corresponding to NM_002730.4:c.409G>A / p.Gly137Arg) as a de novo event. Without additional evidence at the time, the variant was considered to be a candidate for this subject's phenotype (Monies et al 2019 – PMID: 31130284).
Sources: Literature
Intellectual disability syndromic and non-syndromic v0.188 EVC2 Zornitza Stark Marked gene: EVC2 as ready
Intellectual disability syndromic and non-syndromic v0.188 EVC2 Zornitza Stark Gene: evc2 has been classified as Red List (Low Evidence).
Intellectual disability syndromic and non-syndromic v0.188 EVC2 Zornitza Stark Phenotypes for gene: EVC2 were changed from to Ellis-van Creveld syndrome, MIM#225500
Intellectual disability syndromic and non-syndromic v0.187 EVC2 Zornitza Stark Mode of inheritance for gene: EVC2 was changed from Unknown to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.186 EVC2 Zornitza Stark Classified gene: EVC2 as Red List (low evidence)
Intellectual disability syndromic and non-syndromic v0.186 EVC2 Zornitza Stark Gene: evc2 has been classified as Red List (Low Evidence).
Intellectual disability syndromic and non-syndromic v0.185 EVC2 Zornitza Stark reviewed gene: EVC2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ellis-van Creveld syndrome, MIM#225500; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.185 EVC Zornitza Stark Marked gene: EVC as ready
Intellectual disability syndromic and non-syndromic v0.185 EVC Zornitza Stark Gene: evc has been classified as Red List (Low Evidence).
Intellectual disability syndromic and non-syndromic v0.185 EVC Zornitza Stark Phenotypes for gene: EVC were changed from to Ellis-van Creveld syndrome, MIM#225500
Intellectual disability syndromic and non-syndromic v0.184 EVC Zornitza Stark Mode of inheritance for gene: EVC was changed from Unknown to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.183 EVC Zornitza Stark Classified gene: EVC as Red List (low evidence)
Intellectual disability syndromic and non-syndromic v0.183 EVC Zornitza Stark Gene: evc has been classified as Red List (Low Evidence).
Intellectual disability syndromic and non-syndromic v0.182 EVC Zornitza Stark reviewed gene: EVC: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ellis-van Creveld syndrome, MIM#225500; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability syndromic and non-syndromic v0.0 EVC2 Zornitza Stark gene: EVC2 was added
gene: EVC2 was added to Intellectual disability, syndromic and non-syndromic_GHQ. Sources: Expert Review Green,Genetic Health Queensland
Mode of inheritance for gene: EVC2 was set to Unknown
Intellectual disability syndromic and non-syndromic v0.0 EVC Zornitza Stark gene: EVC was added
gene: EVC was added to Intellectual disability, syndromic and non-syndromic_GHQ. Sources: Expert Review Green,Genetic Health Queensland
Mode of inheritance for gene: EVC was set to Unknown