2-237378831-G-C

Variant names:

• chr2-237378831-G-C
• rs200722892
• NM_004369.4:c.2302C>G

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP5

The NM_004369.4(COL6A3):​c.2302C>G​(p.Arg768Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,886 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R768C) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: COL6A3 NM_004369.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 2.24
• Publications: 3 publications found

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]

COL6A3 Gene-Disease associations (from GenCC):

• Bethlem myopathy 1A

  Inheritance: AD, AR, SD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, Ambry Genetics
• collagen 6-related myopathy

  Inheritance: AD, AR Classification: DEFINITIVE Submitted by: ClinGen
• Ullrich congenital muscular dystrophy 1C

  Inheritance: AR Classification: DEFINITIVE Submitted by: G2P
• dystonia 27

  Inheritance: AR Classification: STRONG, SUPPORTIVE, LIMITED, NO_KNOWN Submitted by: Illumina, Labcorp Genetics (formerly Invitae), ClinGen, Ambry Genetics, Orphanet
• Ullrich congenital muscular dystrophy 1A

  Inheritance: AR, AD, SD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Genomics England PanelApp
• Bethlem myopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Ullrich congenital muscular dystrophy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-237378831-G-C is Pathogenic according to our data. Variant chr2-237378831-G-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 191156.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL6A3	NM_004369.4	c.2302C>G	p.Arg768Gly	missense_variant	Exon 6 of 44	ENST00000295550.9	NP_004360.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL6A3	ENST00000295550.9	c.2302C>G	p.Arg768Gly	missense_variant	Exon 6 of 44	1	NM_004369.4	ENSP00000295550.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461886 Hom.: 0 Cov.: 33 AF XY: 0.00000550 AC XY: 4 AN XY: 727244

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.000347 AC: 2 AN: 5768

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1112006

Other (OTH) AF: 0.0000166 AC: 1 AN: 60396

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1

-

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

- -

Bethlem myopathy 1A Uncertain:1

Jun 03, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 768 of the COL6A3 protein (p.Arg768Gly). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with COL6A3-related conditions. ClinVar contains an entry for this variant (Variation ID: 191156). 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 not expected to disrupt COL6A3 protein function. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.21
BayesDel_addAF	Pathogenic	0.17	D
BayesDel_noAF	Uncertain	0.0
CADD	Benign	22
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.56	.;D;.;.;.
Eigen	Benign	0.17
Eigen_PC	Benign	0.081
FATHMM_MKL	Benign	0.54	D
LIST_S2	Uncertain	0.91	D;D;.;D;D
M_CAP	Uncertain	0.13	D
MetaRNN	Uncertain	0.74	D;D;D;D;D
MetaSVM	Benign	-0.31	T
MutationAssessor	Benign	1.8	.;L;.;.;.
PhyloP100		2.2
PrimateAI	Benign	0.36	T
PROVEAN	Uncertain	-4.0	D;D;D;D;D
REVEL	Uncertain	0.39
Sift	Benign	0.097	T;D;T;D;D
Sift4G	Uncertain	0.0030	D;D;D;D;D
Polyphen		1.0	D;D;D;.;.
Vest4		0.78
MutPred		0.48		.;Loss of solvent accessibility (P = 0.0044);.;.;.;
MVP		0.90
MPC		0.73
ClinPred		0.94	D
GERP RS		5.5
Varity_R		0.50
gMVP		0.58
Mutation Taster		=10/90	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs200722892; hg19: chr2-238287474;