2-237361138-C-T

Position:

• chr2-237361138-C-T

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>A​(p.Gly2065Ser) 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. G2065R) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: COL6A3 NM_004369.4 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• 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-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.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.993
• PP5: Variant 2-237361138-C-T is Pathogenic according to our data. 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.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL6A3	NM_004369.4	c.6193G>A	p.Gly2065Ser	missense_variant	16/44	ENST00000295550.9
COL6A3	NM_057167.4	c.5575G>A	p.Gly1859Ser	missense_variant	15/43
COL6A3	NM_057166.5	c.4372G>A	p.Gly1458Ser	missense_variant	13/41

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL6A3	ENST00000295550.9	c.6193G>A	p.Gly2065Ser	missense_variant	16/44	1	NM_004369.4	P1
COL6A3	ENST00000472056.5	c.4372G>A	p.Gly1458Ser	missense_variant	13/41	1
COL6A3	ENST00000353578.9	c.5575G>A	p.Gly1859Ser	missense_variant	15/43	5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:3

Likely pathogenic, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Aug 27, 2020	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Sep 07, 2017	The G2065S variant has not been published as a pathogenic variant, nor has it been reported as a benign variant to our knowledge. The G2065S variant is not observed in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). This variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution occurs within the Gly-X-Y motif in the triple helical (TH) domain of collagen VI, a region that is well-conserved across species. Additionally, a different missense variant at the same position (G2065D) has been reported in an individual with Ullrich congenital muscular dystrophy (Pace et al., 2008). In silico analysis predicts this variant is probably damaging to the protein structure/function. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	May 03, 2016	- -

Bethlem myopathy 1A Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Dec 12, 2023

This sequence change replaces glycine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 2065 of the COL6A3 protein (p.Gly2065Ser). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical suspicion of limb-girdle muscular dystrophy (PMID: 30564623). ClinVar contains an entry for this variant (Variation ID: 56907). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt COL6A3 protein function with a positive predictive value of 80%. This variant disrupts the triple helix domain of COL6A3. Glycine residues within the Gly-Xaa-Yaa repeats of the triple helix domain are required for the structure and stability of fibrillar collagens (PMID: 7695699, 8218237, 19344236). In COL6A3, missense variants at these glycine residues are significantly enriched in individuals with autosomal dominant disease (PMID: 15689448, 24038877) compared to the general population (ExAC). This variant disrupts the p.Gly2065 amino acid residue in COL6A3. Other variant(s) that disrupt this residue have been determined to be pathogenic (Invitae). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.67
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Uncertain	26
DANN	Benign	0.96
DEOGEN2	Pathogenic	0.83	.;D;.;D;.
Eigen	Pathogenic	0.81
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D;D;D;.
M_CAP	Pathogenic	0.94	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.2	.;H;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D
PrimateAI	Uncertain	0.79	T
PROVEAN	Pathogenic	-5.1	D;D;D;.;D
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D;D;D;.;D
Sift4G	Uncertain	0.0040	D;D;D;D;D
Polyphen		1.0	D;D;.;.;D
Vest4		0.92
MutPred		0.93		.;Gain of phosphorylation at G2065 (P = 0.0083);.;.;.;
MVP		0.97
MPC		0.65
ClinPred		1.0	D
GERP RS		5.2
Varity_R		0.96
gMVP		0.98

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; COSMIC: COSV99795815; COSMIC: COSV99795815;