NM_000092.5:c.4923C>A

Variant names:

• chr2-227007475-G-T
• rs121912862
• NM_000092.5:c.4923C>A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000092.5(COL4A4):​c.4923C>A​(p.Cys1641*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,878 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 Pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: COL4A4 NM_000092.5 stop_gained
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 0.975

Genes affected

COL4A4 (HGNC:2206): (collagen type IV alpha 4 chain) This gene encodes one of the six subunits of type IV collagen, the major structural component of basement membranes. This particular collagen IV subunit, however, is only found in a subset of basement membranes. 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. Mutations in this gene are associated with type II autosomal recessive Alport syndrome (hereditary glomerulonephropathy) and with familial benign hematuria (thin basement membrane disease). Two transcripts, differing only in their transcription start sites, have been identified for this gene and, as is common for collagen genes, multiple polyadenylation sites are found in the 3' UTR. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. There are 20 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-227007475-G-T is Pathogenic according to our data. Variant chr2-227007475-G-T is described in ClinVar as [Pathogenic]. Clinvar id is 17408.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr2-227007475-G-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL4A4	NM_000092.5	c.4923C>A	p.Cys1641*	stop_gained	Exon 48 of 48	ENST00000396625.5	NP_000083.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL4A4	ENST00000396625.5	c.4923C>A	p.Cys1641*	stop_gained	Exon 48 of 48	5	NM_000092.5	ENSP00000379866.3
COL4A4	ENST00000682098.1	c.525C>A	p.Cys175*	stop_gained	Exon 3 of 3			ENSP00000508331.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461878 Hom.: 0 Cov.: 35 AF XY: 0.00 AC XY: 0 AN XY: 727234

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Autosomal recessive Alport syndrome Pathogenic:1

Nov 01, 1998

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

not provided Pathogenic:1

Aug 27, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Cys1641*) in the COL4A4 gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 50 amino acid(s) of the COL4A4 protein. This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with Alport syndrome (PMID: 9792860). ClinVar contains an entry for this variant (Variation ID: 17408). This variant disrupts a region of the COL4A4 protein in which other variant(s) (p.Arg1682Gln) have been determined to be pathogenic (PMID: 17216251, 26809805, 27859054). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.51
CADD	Pathogenic	37
DANN	Uncertain	0.99
Eigen	Uncertain	0.59
Eigen_PC	Uncertain	0.43
FATHMM_MKL	Uncertain	0.85	D
Vest4		0.69
GERP RS		2.6

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: rs121912862; hg19: chr2-227872191;