1-147908091-G-A

Position:

• chr1-147908091-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP3_Strong PP5

The NM_005267.5(GJA8):​c.136G>A​(p.Gly46Arg) 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. 13/21 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: GJA8 NM_005267.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 9.92

Genes affected

GJA8 (HGNC:4281): (gap junction protein alpha 8) This gene encodes a transmembrane connexin protein that is necessary for lens growth and maturation of lens fiber cells. The encoded protein is a component of gap junction channels and functions in a calcium and pH-dependent manner. Mutations in this gene have been associated with zonular pulverulent cataracts, nuclear progressive cataracts, and cataract-microcornea syndrome. [provided by RefSeq, Dec 2009]

ACMG classification

Verdict is Likely_pathogenic. Variant got 9 ACMG points.

• PM1: In a topological_domain Extracellular (size 28) in uniprot entity CXA8_HUMAN there are 14 pathogenic changes around while only 0 benign (100%) in NM_005267.5
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.977
• PP5: Variant 1-147908091-G-A is Pathogenic according to our data. Variant chr1-147908091-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 521584.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1, Pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GJA8	NM_005267.5	c.136G>A	p.Gly46Arg	missense_variant	2/2	ENST00000369235.2	NP_005258.2
GJA8	XM_011509417.3	c.136G>A	p.Gly46Arg	missense_variant	1/2		XP_011507719.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GJA8	ENST00000369235.2	c.136G>A	p.Gly46Arg	missense_variant	2/2		NM_005267.5	ENSP00000358238	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 35

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Cataract 1 multiple types Pathogenic:1 Uncertain:1

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 29, 2022	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 expected to disrupt GJA8 protein function. ClinVar contains an entry for this variant (Variation ID: 521584). This missense change has been observed in individuals with autosomal dominant congenital cataracts (PMID: 21686328; Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 46 of the GJA8 protein (p.Gly46Arg). This variant disrupts the p.Gly46 amino acid residue in GJA8. Other variant(s) that disrupt this residue have been observed in individuals with GJA8-related conditions (PMID: 19684000; Invitae), which suggests that this may be a clinically significant amino acid residue. For these reasons, this variant has been classified as Pathogenic. -
Uncertain significance, criteria provided, single submitter	curation	Dept. Genetics and Cancer, Menzies Institute for Medical Research, University of Tasmania	Jan 21, 2023	Variant identified and curated during a GJA8 specific review of the literature in relation to pediatric or congenital cataract. ACMG-AMP criteria applied: PS4(Supporting), PM1(Supporting), PM2(Supporting), PP3. Original variant report: PMID:21686328;32883240. The cataract phenotype reported for this variant is: Total. Additional phenotype/s reported in these individual/s are: Microcornea and Microphthalmia. Gene review and curation guidelines are outlined in: https://doi.org/10.1080/17469899.2023.2160320 -

Inborn genetic diseases Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 17, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.55
CADD	Pathogenic	30
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.97	D
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.96	D
M_CAP	Pathogenic	0.85	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.0	M
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.90	D
PROVEAN	Pathogenic	-7.5	D
REVEL	Pathogenic	0.96
Sift	Uncertain	0.0010	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.97
MutPred		0.74		Gain of solvent accessibility (P = 0.1319);
MVP		0.96
ClinPred		1.0	D
GERP RS		4.9
Varity_R		0.85
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs1553242554; hg19: chr1-147380218;