NM_004369.4:c.6769G>T

Variant names:

• chr2-237351177-C-A
• rs372154635
• NM_004369.4:c.6769G>T

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 2P and 1B. PM2 BP4

The NM_004369.4(COL6A3):​c.6769G>T​(p.Ala2257Ser) 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 benign outcome for this variant. 16/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A2257T) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: COL6A3 NM_004369.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 0.416
• Publications: 0 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 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.3926201).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL6A3	NM_004369.4	c.6769G>T	p.Ala2257Ser	missense_variant	Exon 27 of 44	ENST00000295550.9	NP_004360.2
COL6A3	NM_057167.4	c.6151G>T	p.Ala2051Ser	missense_variant	Exon 26 of 43		NP_476508.2
COL6A3	NM_057166.5	c.4948G>T	p.Ala1650Ser	missense_variant	Exon 24 of 41		NP_476507.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL6A3	ENST00000295550.9	c.6769G>T	p.Ala2257Ser	missense_variant	Exon 27 of 44	1	NM_004369.4	ENSP00000295550.4
COL6A3	ENST00000472056.5	c.4948G>T	p.Ala1650Ser	missense_variant	Exon 24 of 41	1		ENSP00000418285.1
COL6A3	ENST00000353578.9	c.6151G>T	p.Ala2051Ser	missense_variant	Exon 26 of 43	5		ENSP00000315873.4
COL6A3	ENST00000491769.1	n.1023G>T		non_coding_transcript_exon_variant	Exon 4 of 20	5

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Bethlem myopathy 1A Uncertain:1

Jun 03, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with serine, which is neutral and polar, at codon 2257 of the COL6A3 protein (p.Ala2257Ser). 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: 2631076). 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 with a negative predictive value of 80%. 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. -

COL6A3-related disorder Uncertain:1

Sep 06, 2023

PreventionGenetics, part of Exact Sciences

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The COL6A3 c.6769G>T variant is predicted to result in the amino acid substitution p.Ala2257Ser. To our knowledge, this variant has not been reported in the literature or in a large population database (http://gnomad.broadinstitute.org), indicating this variant is rare. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.080
BayesDel_addAF	Benign	-0.031	T
BayesDel_noAF	Benign	-0.28
CADD	Benign	7.6
DANN	Benign	0.74
DEOGEN2	Benign	0.13	.;T;.;T;.
Eigen	Benign	-0.80
Eigen_PC	Benign	-0.82
FATHMM_MKL	Benign	0.098	N
LIST_S2	Benign	0.75	T;T;T;T;.
M_CAP	Uncertain	0.11	D
MetaRNN	Benign	0.39	T;T;T;T;T
MetaSVM	Benign	-0.41	T
MutationAssessor	Benign	0.86	.;L;.;.;.
PhyloP100		0.42
PrimateAI	Benign	0.38	T
PROVEAN	Benign	-0.54	N;N;N;.;N
REVEL	Benign	0.12
Sift	Uncertain	0.020	D;D;D;.;D
Sift4G	Uncertain	0.020	D;D;D;D;D
Polyphen		0.032	B;B;.;.;B
Vest4		0.18
MutPred		0.48		.;Gain of relative solvent accessibility (P = 0.0023);.;.;.;
MVP		0.75
MPC		0.13
ClinPred		0.11	T
GERP RS		2.5
Varity_R		0.043
gMVP		0.086
Mutation Taster		=93/7	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		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: rs372154635; hg19: chr2-238259820;