rs1553559646

Positions:

• chr2-237372292-T-G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_004369.4(COL6A3):​c.3725A>C​(p.Gln1242Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: COL6A3 NM_004369.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.22

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 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.782

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
COL6A3	NM_004369.4	c.3725A>C	p.Gln1242Pro	missense_variant	9/44	ENST00000295550.9	NP_004360.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
COL6A3	ENST00000295550.9	c.3725A>C	p.Gln1242Pro	missense_variant	9/44	1	NM_004369.4	ENSP00000295550	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000756

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

Aug 29, 2017

In summary, this variant has uncertain impact on COL6A3 function. The available evidence is currently insufficient to determine its role in disease. Therefore, 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 has not been reported in the literature in individuals with a COL6A3-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces glutamine with proline at codon 1242 of the COL6A3 protein (p.Gln1242Pro). The glutamine residue is weakly conserved and there is a moderate physicochemical difference between glutamine and proline. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Uncertain	0.059	T
BayesDel_noAF	Benign	-0.15
CADD	Benign	19
DANN	Uncertain	0.98
DEOGEN2	Benign	0.28	.;T;.;T;.;.;.
Eigen	Benign	-0.055
Eigen_PC	Benign	-0.15
FATHMM_MKL	Benign	0.58	D
LIST_S2	Uncertain	0.89	D;D;D;D;.;D;D
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.78	D;D;D;D;D;D;D
MetaSVM	Benign	-0.45	T
MutationAssessor	Benign	1.8	.;L;.;.;.;.;.
MutationTaster	Benign	1.0	N;N;N;N;N;N;N;N
PrimateAI	Benign	0.33	T
PROVEAN	Uncertain	-2.6	D;D;N;.;D;D;D
REVEL	Uncertain	0.55
Sift	Benign	0.13	T;T;T;.;T;T;T
Sift4G	Uncertain	0.0090	D;D;D;D;D;D;D
Polyphen		1.0	D;P;.;.;D;.;.
Vest4		0.63
MutPred		0.61		.;Gain of sheet (P = 0.0827);.;.;.;.;.;
MVP		0.82
MPC		0.69
ClinPred		0.52	D
GERP RS		3.1
Varity_R		0.81
gMVP		0.80

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: rs1553559646; hg19: chr2-238280935;