6-121447073-C-A

Position:

• chr6-121447073-C-A

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PP2 PP3_Strong PP5

The NM_000165.5(GJA1):​c.226C>A​(p.Arg76Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 32)
• Consequence: GJA1 NM_000165.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:4 U:1
• Conservation: PhyloP100: 7.91

Genes affected

GJA1 (HGNC:4274): (gap junction protein alpha 1) This gene is a member of the connexin gene family. The encoded protein is a component of gap junctions, which are composed of arrays of intercellular channels that provide a route for the diffusion of low molecular weight materials from cell to cell. The encoded protein is the major protein of gap junctions in the heart that are thought to have a crucial role in the synchronized contraction of the heart and in embryonic development. A related intronless pseudogene has been mapped to chromosome 5. Mutations in this gene have been associated with oculodentodigital dysplasia, autosomal recessive craniometaphyseal dysplasia and heart malformations. [provided by RefSeq, May 2014]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PM1: In a topological_domain Extracellular (size 31) in uniprot entity CXA1_HUMAN there are 5 pathogenic changes around while only 0 benign (100%) in NM_000165.5
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), GJA1. . Gene score misZ 1.2784 (greater than the threshold 3.09). Trascript score misZ 3.3775 (greater than threshold 3.09). GenCC has associacion of gene with craniometaphyseal dysplasia, autosomal recessive, Hallermann-Streiff syndrome, syndactyly type 3, oculodentodigital dysplasia, nonsyndromic genetic hearing loss, hypoplastic left heart syndrome 1, autosomal dominant palmoplantar keratoderma and congenital alopecia, oculodentodigital dysplasia, autosomal recessive, craniometaphyseal dysplasia, erythrokeratodermia variabilis et progressiva 3, erythrokeratodermia variabilis.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.995
• PP5: Variant 6-121447073-C-A is Pathogenic according to our data. Variant chr6-121447073-C-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 16997.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=3, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GJA1	NM_000165.5	c.226C>A	p.Arg76Ser	missense_variant	2/2	ENST00000282561.4	NP_000156.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GJA1	ENST00000282561.4	c.226C>A	p.Arg76Ser	missense_variant	2/2	1	NM_000165.5	ENSP00000282561	P1
GJA1	ENST00000647564.1	c.226C>A	p.Arg76Ser	missense_variant	2/2			ENSP00000497565	P1
GJA1	ENST00000649003.1	c.226C>A	p.Arg76Ser	missense_variant	2/2			ENSP00000497283	P1
GJA1	ENST00000650427.1	c.226C>A	p.Arg76Ser	missense_variant	2/2			ENSP00000497367	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:4 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Oculodentodigital dysplasia Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	May 12, 2014	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Feb 01, 2003	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Greenwood Genetic Center Diagnostic Laboratories, Greenwood Genetic Center	Dec 07, 2021	PM2, PM5, PS5_Supporting, PP3 -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Jan 09, 2024

Reported previously segregating in a family with oculodentodigital dysplasia however detailed clinical or segregation information was not specified (PMID: 10331943; 12457340); Published functional studies demonstrate a damaging effect as R76S results in reduced gap activity in vitro (PMID: 34630166); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 32318302, 30626485, Katturajan 2023[computational], 37395717, 34630166, 12457340) -

Oculodentodigital dysplasia, autosomal recessive Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jun 20, 2022

Experimental studies have shown that this missense change affects GJA1 function (PMID: 34630166). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). ClinVar contains an entry for this variant (Variation ID: 16997). This missense change has been observed in individual(s) with oculodentodigital dysplasia (PMID: 12457340). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with serine, which is neutral and polar, at codon 76 of the GJA1 protein (p.Arg76Ser). This variant disrupts the p.Arg76 amino acid residue in GJA1. Other variant(s) that disrupt this residue have been observed in individuals with GJA1-related conditions (PMID: 12457340, 24115525), which suggests that this may be a clinically significant amino acid residue. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.59
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.98	D;D;D;D;D
Eigen	Pathogenic	0.92
Eigen_PC	Pathogenic	0.87
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.87	.;.;.;.;D
M_CAP	Pathogenic	0.81	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.2	M;M;M;M;M
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.93	D
PROVEAN	Pathogenic	-5.4	.;.;D;.;.
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	.;.;D;.;.
Sift4G	Uncertain	0.0020	.;.;D;.;.
Polyphen		1.0	D;D;D;D;D
Vest4		0.94
MutPred		0.98		Gain of catalytic residue at S73 (P = 0.1025);Gain of catalytic residue at S73 (P = 0.1025);Gain of catalytic residue at S73 (P = 0.1025);Gain of catalytic residue at S73 (P = 0.1025);Gain of catalytic residue at S73 (P = 0.1025);
MVP		0.99
MPC		1.4
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.94
gMVP		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs267606845; hg19: chr6-121768219;