rs890268146

Positions:

• chr2-237340968-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_004369.4(COL6A3):​c.7948G>A​(p.Asp2650Asn) variant causes a missense change. The variant allele was found at a frequency of 0.00000821 in 1,461,862 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000082 (0 hom.)
• Consequence: COL6A3 NM_004369.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.05

Genes affected

COL6A3 (HGNC:2213): (collagen type VI alpha 3 chain) This gene encodes the alpha-3 chain, one of the three alpha chains of type VI collagen, a beaded filament collagen found in most connective tissues. The alpha-3 chain of type VI collagen is much larger than the alpha-1 and -2 chains. This difference in size is largely due to an increase in the number of subdomains, similar to von Willebrand Factor type A domains, that are found in the amino terminal globular domain of all the alpha chains. 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 the type VI collagen genes are associated with Bethlem myopathy, a rare autosomal dominant proximal myopathy with early childhood onset. Mutations in this gene are also a cause of Ullrich congenital muscular dystrophy, also referred to as Ullrich scleroatonic muscular dystrophy, an autosomal recessive congenital myopathy that is more severe than Bethlem myopathy. Multiple transcript variants have been identified, but the full-length nature of only some of these variants has been described. [provided by RefSeq, Jun 2009]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
COL6A3	NM_004369.4	c.7948G>A	p.Asp2650Asn	missense_variant	38/44	ENST00000295550.9	NP_004360.2
COL6A3	NM_057167.4	c.7330G>A	p.Asp2444Asn	missense_variant	37/43		NP_476508.2
COL6A3	NM_057166.5	c.6127G>A	p.Asp2043Asn	missense_variant	35/41		NP_476507.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
COL6A3	ENST00000295550.9	c.7948G>A	p.Asp2650Asn	missense_variant	38/44	1	NM_004369.4	ENSP00000295550	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000821 AC: 12 AN: 1461862 Hom.: 0 Cov.: 33 AF XY: 0.00000688 AC XY: 5 AN XY: 727236

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: 0.00000899

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome Cov.: 33

Alfa AF: 0.0000468 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Bethlem myopathy 1A Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 24, 2016

In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a COL6A3-related disease. This sequence change replaces aspartic acid with asparagine at codon 2650 of the COL6A3 protein (p.Asp2650Asn). The aspartic acid residue is weakly conserved and there is a small physicochemical difference between aspartic acid and asparagine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.096
BayesDel_addAF	Benign	-0.00040	T
BayesDel_noAF	Benign	-0.24
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Benign	0.22	.;T;.;T;.
Eigen	Uncertain	0.41
Eigen_PC	Uncertain	0.47
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.93	D;D;D;D;.
M_CAP	Uncertain	0.089	D
MetaRNN	Uncertain	0.53	D;D;D;D;D
MetaSVM	Uncertain	0.17	D
MutationAssessor	Uncertain	2.6	.;M;.;.;.
MutationTaster	Benign	0.65	N;N;N;N;N;N
PrimateAI	Benign	0.47	T
PROVEAN	Benign	-1.5	N;N;N;.;N
REVEL	Uncertain	0.35
Sift	Benign	0.076	T;T;D;.;T
Sift4G	Uncertain	0.013	D;D;D;D;D
Polyphen		0.59	P;D;.;.;P
Vest4		0.38
MutPred		0.52		.;Gain of MoRF binding (P = 0.0633);.;.;.;
MVP		0.84
MPC		0.14
ClinPred		0.84	D
GERP RS		5.0
Varity_R		0.15
gMVP		0.47

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: rs890268146; hg19: chr2-238249611;