2-227164728-T-G

Position:

• chr2-227164728-T-G

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PS1_Moderate PM2

The NM_000091.5(COL4A3):​c.2T>G​(p.Met1?) variant causes a start lost change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000726 in 1,378,204 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 7.3e-7 (0 hom.)
• Consequence: COL4A3 NM_000091.5 start_lost
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.421

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]

COL4A3 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Start lost variant, no new inframe start found.
• PS1: Another start lost variant in NM_000091.5 (COL4A3) was described as [Pathogenic] in Lovd
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
COL4A3	NM_000091.5	c.2T>G	p.Met1?	start_lost	1/52	ENST00000396578.8	NP_000082.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
COL4A3	ENST00000396578.8	c.2T>G	p.Met1?	start_lost	1/52	1	NM_000091.5	ENSP00000379823.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 7.26e-7 AC: 1 AN: 1378204 Hom.: 0 Cov.: 31 AF XY: 0.00000147 AC XY: 1 AN XY: 680080

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: 9.28e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.25
CADD	Benign	18
DANN	Benign	0.93
DEOGEN2	Benign	0.081	T
Eigen	Benign	-0.36
Eigen_PC	Benign	-0.37
FATHMM_MKL	Benign	0.51	D
LIST_S2	Uncertain	0.90	D
M_CAP	Pathogenic	0.98	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Uncertain	0.14	D
PROVEAN	Benign	0.070	N
REVEL	Uncertain	0.55
Sift	Uncertain	0.0040	D
Sift4G	Uncertain	0.0050	D
Polyphen		0.14	B
Vest4		0.83
MutPred		0.92		Gain of MoRF binding (P = 0.0065);
MVP		0.78
ClinPred		0.81	D
GERP RS		4.0
Varity_R		0.90
gMVP		0.88

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: rs1553725815; hg19: chr2-228029444;