2-227245981-G-A

Position:

• chr2-227245981-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_000091.5(COL4A3):​c.352G>A​(p.Gly118Arg) variant causes a missense change. The variant allele was found at a frequency of 0.0000149 in 1,613,792 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000015 (0 hom.)
• Consequence: COL4A3 NM_000091.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts P:1 U:3
• Conservation: PhyloP100: 5.11

Genes affected

COL4A3 (HGNC:2204): (collagen type IV alpha 3 chain) Type IV collagen, the major structural component of basement membranes, is a multimeric protein composed of 3 alpha subunits. These subunits are encoded by 6 different genes, alpha 1 through alpha 6, each of which can form a triple helix structure with 2 other subunits to form type IV collagen. This gene encodes alpha 3. In the Goodpasture syndrome, autoantibodies bind to the collagen molecules in the basement membranes of alveoli and glomeruli. The epitopes that elicit these autoantibodies are localized largely to the non-collagenous C-terminal domain of the protein. A specific kinase phosphorylates amino acids in this same C-terminal region and the expression of this kinase is upregulated during pathogenesis. This gene is also linked to an autosomal recessive form of Alport syndrome. The mutations contributing to this syndrome are also located within the exons that encode this C-terminal region. Like the other members of the type IV collagen gene family, this gene is organized in a head-to-head conformation with another type IV collagen gene so that each gene pair shares a common promoter. [provided by RefSeq, Jun 2010]

MFF-DT (HGNC:41067): (MFF divergent transcript)

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.996

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
COL4A3	NM_000091.5	c.352G>A	p.Gly118Arg	missense_variant	6/52	ENST00000396578.8	NP_000082.2
MFF-DT	NR_102371.1	n.1593-7807C>T		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
COL4A3	ENST00000396578.8	c.352G>A	p.Gly118Arg	missense_variant	6/52	1	NM_000091.5	ENSP00000379823	P1
MFF-DT	ENST00000439598.6	n.1593-7807C>T		intron_variant, non_coding_transcript_variant		1

Frequencies

GnomAD3 genomes AF: 0.0000131 AC: 2 AN: 152172 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000294

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.0000151 AC: 22 AN: 1461620 Hom.: 0 Cov.: 30 AF XY: 0.0000138 AC XY: 10 AN XY: 727120

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: 0.0000198

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000131 AC: 2 AN: 152172 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74338

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000756

Asia WGS AF: 0.000289 AC: 1 AN: 3478

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1 Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1 Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Mar 29, 2022	This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 118 of the COL4A3 protein (p.Gly118Arg). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical features of COL4A3-related conditions (PMID: 25596306). ClinVar contains an entry for this variant (Variation ID: 552802). 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 COL4A3 protein function. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. 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. -
Likely pathogenic, no assertion criteria provided	research	Gharavi Laboratory, Columbia University	Sep 16, 2018	- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Feb 18, 2022

Variant summary: COL4A3 c.352G>A (p.Gly118Arg) results in a non-conservative amino acid change located in the Collagen triple helix repeat (IPR008160) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 249428 control chromosomes (gnomAD). c.352G>A has been reported in the literature in individuals affected with focal segmental glomerulosclerosis and hematuria (Xie_2014, Gibson_2021). These reports do not provide unequivocal conclusions about association of the variant with Alport Syndrome, Autosomal Recessive. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. Three ClinVar submitters have assessed the variant since 2014: one classified the variant as uncertain significance and two as likely pathogenic. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Autosomal recessive Alport syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Counsyl

Jul 07, 2017

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.62
BayesDel_addAF	Pathogenic	0.54	D
BayesDel_noAF	Pathogenic	0.54
CADD	Pathogenic	27
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.67	D
Eigen	Uncertain	0.67
Eigen_PC	Uncertain	0.47
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Uncertain	0.95	D
M_CAP	Pathogenic	0.86	D
MetaRNN	Pathogenic	1.0	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.3	H
MutationTaster	Benign	0.91	D
PrimateAI	Uncertain	0.70	T
PROVEAN	Pathogenic	-7.2	D
REVEL	Pathogenic	0.90
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.99
MutPred		0.97		Gain of methylation at G118 (P = 0.1105);
MVP		0.95
MPC		0.83
ClinPred		1.0	D
GERP RS		5.5
Varity_R		0.87
gMVP		0.94

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: rs1293137291; hg19: chr2-228110697;