6-121447260-G-T

Variant names:

• chr6-121447260-G-T
• rs1554201019
• NM_000165.5:c.413G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate

The NM_000165.5(GJA1):​c.413G>T​(p.Gly138Val) 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. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G138S) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GJA1 NM_000165.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.60
• Publications: 0 publications found

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]

GJA1 Gene-Disease associations (from GenCC):

• hypoplastic left heart syndrome 1

  Inheritance: AD Classification: DEFINITIVE Submitted by: G2P
• oculodentodigital dysplasia

  Inheritance: AD, SD, AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Labcorp Genetics (formerly Invitae), Ambry Genetics
• autosomal dominant palmoplantar keratoderma and congenital alopecia

  Inheritance: AD Classification: STRONG, SUPPORTIVE, LIMITED Submitted by: Orphanet, Ambry Genetics, Genomics England PanelApp, G2P
• erythrokeratodermia variabilis et progressiva 3

  Inheritance: AD Classification: STRONG, MODERATE, LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), Genomics England PanelApp, G2P
• oculodentodigital dysplasia, autosomal recessive

  Inheritance: AR Classification: STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
• craniometaphyseal dysplasia

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• erythrokeratodermia variabilis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• syndactyly type 3

  Inheritance: AD, Unknown Classification: SUPPORTIVE, LIMITED Submitted by: Orphanet, Ambry Genetics, Labcorp Genetics (formerly Invitae)
• Hallermann-Streiff syndrome

  Inheritance: AR Classification: LIMITED Submitted by: G2P
• craniometaphyseal dysplasia, autosomal recessive

  Inheritance: Unknown, AR Classification: LIMITED Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
• nonsyndromic genetic hearing loss

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_000165.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr6-121447259-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 537756.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP2: Missense variant in the GJA1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 41 curated pathogenic missense variants (we use a threshold of 10). The gene has 1 curated benign missense variants. Gene score misZ: 1.2784 (below the threshold of 3.09). Trascript score misZ: 3.3775 (above the threshold of 3.09). GenCC associations: The gene is linked to craniometaphyseal dysplasia, autosomal recessive, erythrokeratodermia variabilis et progressiva 3, oculodentodigital dysplasia, autosomal dominant palmoplantar keratoderma and congenital alopecia, hypoplastic left heart syndrome 1, craniometaphyseal dysplasia, syndactyly type 3, oculodentodigital dysplasia, autosomal recessive, nonsyndromic genetic hearing loss, Hallermann-Streiff syndrome, erythrokeratodermia variabilis.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.845

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GJA1	NM_000165.5	c.413G>T	p.Gly138Val	missense_variant	Exon 2 of 2	ENST00000282561.4	NP_000156.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GJA1	ENST00000282561.4	c.413G>T	p.Gly138Val	missense_variant	Exon 2 of 2	1	NM_000165.5	ENSP00000282561.3
GJA1	ENST00000647564.1	c.413G>T	p.Gly138Val	missense_variant	Exon 2 of 2			ENSP00000497565.1
GJA1	ENST00000649003.1	c.413G>T	p.Gly138Val	missense_variant	Exon 2 of 2			ENSP00000497283.1
GJA1	ENST00000650427.1	c.413G>T	p.Gly138Val	missense_variant	Exon 2 of 2			ENSP00000497367.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Oculodentodigital dysplasia, autosomal recessive Uncertain:1

Apr 25, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 138 of the GJA1 protein (p.Gly138Val). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with GJA1-related conditions. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt GJA1 protein function with a negative predictive value of 80%. This variant disrupts the p.Gly138 amino acid residue in GJA1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 18946008, 19338053, 25388818). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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	0.98
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.080
CADD	Benign	23
DANN	Uncertain	0.98
DEOGEN2	Uncertain	0.71	D;D;D;D;D
Eigen	Uncertain	0.35
Eigen_PC	Uncertain	0.23
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.91	.;.;.;.;D
M_CAP	Uncertain	0.16	D
MetaRNN	Pathogenic	0.85	D;D;D;D;D
MetaSVM	Pathogenic	0.96	D
MutationAssessor	Uncertain	2.1	M;M;M;M;M
PhyloP100		9.6
PrimateAI	Pathogenic	0.87	D
PROVEAN	Benign	-1.0	.;.;N;.;.
REVEL	Uncertain	0.62
Sift	Benign	0.46	.;.;T;.;.
Sift4G	Benign	0.51	.;.;T;.;.
Polyphen		1.0	D;D;D;D;D
Vest4		0.83
MutPred		0.52		Loss of disorder (P = 0.0351);Loss of disorder (P = 0.0351);Loss of disorder (P = 0.0351);Loss of disorder (P = 0.0351);Loss of disorder (P = 0.0351);
MVP		0.98
MPC		0.64
ClinPred		0.87	D
GERP RS		4.5
Varity_R		0.52
gMVP		0.94
Mutation Taster		=21/79	disease causing

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

Other links and lift over

dbSNP: rs1554201019; hg19: chr6-121768406; COSMIC: COSV56998948;