rs1555877364

chr21-46132479-T-TG

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_001849.4(COL6A2):c.2988dup(p.Phe997ValfsTer7) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. V996V) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 34)
• Consequence: COL6A2 NM_001849.4 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 1.50

Genes affected

COL6A2 (HGNC:2212): (collagen type VI alpha 2 chain) This gene encodes one of the three alpha chains of type VI collagen, a beaded filament collagen found in most connective tissues. The product of this gene contains several domains similar to von Willebrand Factor type A domains. These domains have been shown to bind extracellular matrix proteins, an interaction that explains the importance of this collagen in organizing matrix components. Mutations in this gene are associated with Bethlem myopathy and Ullrich scleroatonic muscular dystrophy. Three transcript variants have been identified for this gene. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 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 5 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 21-46132479-T-TG is Pathogenic according to our data. Variant chr21-46132479-T-TG is described in ClinVar as [Pathogenic]. Clinvar id is 476481.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL6A2	NM_001849.4	c.2988dup	p.Phe997ValfsTer7	frameshift_variant	28/28	ENST00000300527.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL6A2	ENST00000300527.9	c.2988dup	p.Phe997ValfsTer7	frameshift_variant	28/28	1	NM_001849.4	P1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 34

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Bethlem myopathy 1A Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Sep 15, 2020

This variant disrupts the C-terminus of the COL6A2 protein. Other variant(s) that disrupt this region (p.Tyr1002*) have been determined to be pathogenic (PMID: 29419890). This suggests that variants that disrupt this region of the protein are likely to be causative of disease. For these reasons, this variant has been classified as Pathogenic. This variant has not been reported in the literature in individuals with COL6A2-related conditions. This sequence change results in a premature translational stop signal in the COL6A2 gene (p.Phe997Valfs*7). While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 23 amino acids of the COL6A2 protein. This variant is not present in population databases (ExAC no frequency). -

Computational scores

Source: dbNSFP v4.3

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: rs1555877364; hg19: chr21-47552393;