2-237365784-G-T

Position:

• chr2-237365784-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_004369.4(COL6A3):​c.5752C>A​(p.Arg1918Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,198 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: COL6A3 NM_004369.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.17

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 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.2932651).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
COL6A3	NM_004369.4	c.5752C>A	p.Arg1918Ser	missense_variant	12/44	ENST00000295550.9	NP_004360.2
COL6A3	NM_057167.4	c.5134C>A	p.Arg1712Ser	missense_variant	11/43		NP_476508.2
COL6A3	NM_057166.5	c.3931C>A	p.Arg1311Ser	missense_variant	9/41		NP_476507.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
COL6A3	ENST00000295550.9	c.5752C>A	p.Arg1918Ser	missense_variant	12/44	1	NM_004369.4	ENSP00000295550	P1
COL6A3	ENST00000472056.5	c.3931C>A	p.Arg1311Ser	missense_variant	9/41	1		ENSP00000418285
COL6A3	ENST00000353578.9	c.5134C>A	p.Arg1712Ser	missense_variant	11/43	5		ENSP00000315873

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152198 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152198 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74356

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

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

May 06, 2017

In summary, this variant is a novel missense change that is not predicted to affect protein function. There is no indication that it causes disease, but the available evidence is currently insufficient to prove that conclusively. 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 (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies. 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 arginine with serine at codon 1918 of the COL6A3 protein (p.Arg1918Ser). The arginine residue is moderately conserved and there is a moderate physicochemical difference between arginine and serine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.34
BayesDel_addAF	Uncertain	0.029	T
BayesDel_noAF	Benign	-0.20
CADD	Uncertain	24
DANN	Benign	0.97
DEOGEN2	Benign	0.19	.;T;.;T;.
Eigen	Benign	-0.0033
Eigen_PC	Benign	0.12
FATHMM_MKL	Uncertain	0.87	D
LIST_S2	Benign	0.83	T;T;T;T;.
M_CAP	Benign	0.0098	T
MetaRNN	Benign	0.29	T;T;T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	2.0	.;M;.;.;.
MutationTaster	Benign	0.99	D;D;D;D;D;D
PrimateAI	Uncertain	0.51	T
PROVEAN	Benign	-1.7	N;N;N;.;N
REVEL	Benign	0.13
Sift	Benign	0.067	T;T;T;.;T
Sift4G	Benign	0.12	T;T;T;T;T
Polyphen		0.56	P;B;.;.;P
Vest4		0.47
MutPred		0.38		.;Gain of phosphorylation at R1918 (P = 0.0797);.;.;.;
MVP		0.63
MPC		0.19
ClinPred		0.52	D
GERP RS		4.4
Varity_R		0.14
gMVP		0.76

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: rs750367811; hg19: chr2-238274427;