rs121917827

Positions:

• chr13-20143062-C-T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Moderate

The NM_021954.4(GJA3):​c.227G>A​(p.Arg76His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,484 control chromosomes in the GnomAD database, with no homozygous occurrence. 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 Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R76G) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: GJA3 NM_021954.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 7.80

Genes affected

GJA3 (HGNC:4277): (gap junction protein alpha 3) The protein encoded by this gene is a connexin and is a component of lens fiber gap junctions. Defects in this gene are a cause of zonular pulverulent cataract type 3 (CZP3). [provided by RefSeq, Jan 2010]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PM1: In a mutagenesis_site Abolishes formation of gap junctions. No significant effect on formation of functional hemichannels. (size 0) in uniprot entity CXA3_HUMAN
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrnull-null-null-null is described in UniProt as null.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.979
• PP5: Variant 13-20143062-C-T is Pathogenic according to our data. Variant chr13-20143062-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 16981.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GJA3	NM_021954.4	c.227G>A	p.Arg76His	missense_variant	2/2	ENST00000241125.4	NP_068773.2
GJA3	XM_011535048.3	c.227G>A	p.Arg76His	missense_variant	2/2		XP_011533350.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GJA3	ENST00000241125.4	c.227G>A	p.Arg76His	missense_variant	2/2	3	NM_021954.4	ENSP00000241125	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461484 Hom.: 0 Cov.: 34 AF XY: 0.00 AC XY: 0 AN XY: 726984

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000756

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Cataract 14 multiple types Pathogenic:2

Likely pathogenic, 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 GJA3 specific review of the literature in relation to pediatric or congenital cataract. ACMG-AMP criteria applied: PP1(Strong), PM1, PS4(Supporting), PM2(Supporting), PP3. Original variant report: PMID:15286166;19182255. The cataract phenotype/s reported for this variant are: Pulverulent nuclear and some with cortical lamellar opacity, and Nuclear with lamellar and anterior Y-sutural opacity. Gene review and curation guidelines are outlined in: https://doi.org/10.1080/17469899.2023.2160320 -
Pathogenic, no assertion criteria provided	literature only	OMIM	Aug 01, 2004	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.72
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.55
CADD	Pathogenic	31
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.92	D
Eigen	Pathogenic	0.92
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.96	D
M_CAP	Pathogenic	0.82	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.0	M
MutationTaster	Benign	1.0	A
PrimateAI	Uncertain	0.75	T
PROVEAN	Pathogenic	-4.8	D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.89
MutPred		0.82		Gain of catalytic residue at Q81 (P = 0);
MVP		0.99
MPC		2.3
ClinPred		1.0	D
GERP RS		5.4
Varity_R		0.88
gMVP		0.99

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: rs121917827; hg19: chr13-20717201;