chr2-237361138-C-G

Position:

• chr2-237361138-C-G

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_004369.4(COL6A3):​c.6193G>C​(p.Gly2065Arg) variant causes a missense change involving the alteration of a 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G2065S) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: COL6A3 NM_004369.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 7.37

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 Pathogenic. Variant got 18 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 5 uncertain in NM_004369.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-237361138-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 56907.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.995
• PP5: Variant 2-237361138-C-G is Pathogenic according to our data. Variant chr2-237361138-C-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 284796.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-237361138-C-G is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL6A3	NM_004369.4	c.6193G>C	p.Gly2065Arg	missense_variant	16/44	ENST00000295550.9
COL6A3	NM_057167.4	c.5575G>C	p.Gly1859Arg	missense_variant	15/43
COL6A3	NM_057166.5	c.4372G>C	p.Gly1458Arg	missense_variant	13/41

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL6A3	ENST00000295550.9	c.6193G>C	p.Gly2065Arg	missense_variant	16/44	1	NM_004369.4	P1
COL6A3	ENST00000472056.5	c.4372G>C	p.Gly1458Arg	missense_variant	13/41	1
COL6A3	ENST00000353578.9	c.5575G>C	p.Gly1859Arg	missense_variant	15/43	5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Bethlem myopathy 1A Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 10, 2018

This sequence change replaces glycine with arginine at codon 2065 of the COL6A3 protein (p.Gly2065Arg). The glycine residue is highly conserved and there is a moderate physicochemical difference between glycine and arginine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with COL6A3-related disease. ClinVar contains an entry for this variant (Variation ID: 284796). 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: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C15"). A different missense substitution at this codon (p.Gly2065Asp) has been determined to be pathogenic (PMID: 18825676, 27447704). Glycine residues within the triple helix region are crucial to maintain fibrillar collagens structure and stability (PMID: 7695699, 19344236). In the case of COL6A3, missense substitutions that affect glycine residues within the triplex helix domain have been reported in many patients affected with collagen VI myopathy (PMID: 24038877). For these reasons, this variant has been classified as Pathogenic. -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Eurofins Ntd Llc (ga)

Dec 11, 2015

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.96
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Uncertain	25
DANN	Benign	0.90
DEOGEN2	Pathogenic	0.84	.;D;.;D;.
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.67
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.94	D;D;D;D;.
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D
MetaSVM	Pathogenic	0.97	D
MutationAssessor	Pathogenic	3.8	.;H;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Pathogenic	0.84	D
PROVEAN	Pathogenic	-6.8	D;D;D;.;D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D;D;D;.;D
Sift4G	Pathogenic	0.0	D;D;D;D;D
Polyphen		1.0	D;D;.;.;D
Vest4		0.97
MutPred		0.96		.;Gain of solvent accessibility (P = 0.0012);.;.;.;
MVP		0.98
MPC		0.71
ClinPred		0.99	D
GERP RS		5.2
Varity_R		0.97
gMVP		0.99

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: rs397515332; hg19: chr2-238269781;