21-46116028-G-A

Variant names:

• chr21-46116028-G-A
• rs794727855
• NM_001849.4:c.875G>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP3_Strong PP5_Moderate

The NM_001849.4(COL6A2):​c.875G>A​(p.Gly292Asp) 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 Pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G292S) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: COL6A2 NM_001849.4 missense
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 7.71
• Publications: 0 publications found

Genes affected

COL6A2 (HGNC:2212): (collagen type VI alpha 2 chain) This gene encodes one of the three alpha chains of type VI collagen, a beaded filament collagen found in most connective tissues. The product of this gene contains several domains similar to von Willebrand Factor type A domains. 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 this gene are associated with Bethlem myopathy and Ullrich scleroatonic muscular dystrophy. Three transcript variants have been identified for this gene. [provided by RefSeq, Jul 2008]

COL6A2 Gene-Disease associations (from GenCC):

• collagen 6-related myopathy

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

  Inheritance: AR, AD Classification: DEFINITIVE Submitted by: G2P
• Bethlem myopathy 1A

  Inheritance: AD, AR Classification: STRONG Submitted by: Genomics England PanelApp
• Ullrich congenital muscular dystrophy 1A

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

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

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• myosclerosis

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 6 uncertain in NM_001849.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr21-46116027-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 1351958.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.992
• PP5: Variant 21-46116028-G-A is Pathogenic according to our data. Variant chr21-46116028-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 2138406.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL6A2	NM_001849.4	c.875G>A	p.Gly292Asp	missense_variant	Exon 7 of 28	ENST00000300527.9	NP_001840.3
COL6A2	NM_058174.3	c.875G>A	p.Gly292Asp	missense_variant	Exon 7 of 28		NP_478054.2
COL6A2	NM_058175.3	c.875G>A	p.Gly292Asp	missense_variant	Exon 7 of 28		NP_478055.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL6A2	ENST00000300527.9	c.875G>A	p.Gly292Asp	missense_variant	Exon 7 of 28	1	NM_001849.4	ENSP00000300527.4
COL6A2	ENST00000397763.6	c.875G>A	p.Gly292Asp	missense_variant	Exon 7 of 28	5		ENSP00000380870.1
COL6A2	ENST00000409416.6	c.875G>A	p.Gly292Asp	missense_variant	Exon 6 of 27	5		ENSP00000387115.1
COL6A2	ENST00000485591.1	n.531G>A		non_coding_transcript_exon_variant	Exon 3 of 7	3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Bethlem myopathy 1A Pathogenic:1

Mar 01, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Gly292 amino acid residue in COL6A2. Other variant(s) that disrupt this residue have been observed in individuals with COL6A2-related conditions (PMID: 17785673, 24038877, 29419890, 32403337), which suggests that this may be a clinically significant amino acid residue. This variant disrupts the triple helix domain of COL6A2. 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 COL6A2, missense variants at these glycine residues are significantly enriched in individuals with autosomal dominant disease (PMID: 15689448, 24038877) compared to the general population (ExAC). 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 COL6A2 protein function. This missense change has been observed in individual(s) with autosomal dominant Ullrich congenital muscular dystrophy (PMID: 24038877). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with aspartic acid, which is acidic and polar, at codon 292 of the COL6A2 protein (p.Gly292Asp). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.88	D;.;.;.
Eigen	Pathogenic	0.95
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.90	D;D;.;D
M_CAP	Pathogenic	0.98	D
MetaRNN	Pathogenic	0.99	D;D;D;D
MetaSVM	Pathogenic	0.97	D
MutationAssessor	Pathogenic	4.3	H;H;H;H
PhyloP100		7.7
PrimateAI	Pathogenic	0.93	D
PROVEAN	Uncertain	-4.1	D;D;D;D
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D
Polyphen		1.0	D;D;D;D
Vest4		0.99
MutPred		0.94		Loss of catalytic residue at P288 (P = 0.069);Loss of catalytic residue at P288 (P = 0.069);Loss of catalytic residue at P288 (P = 0.069);Loss of catalytic residue at P288 (P = 0.069);
MVP		0.99
MPC		0.68
ClinPred		1.0	D
GERP RS		4.3
Varity_R		0.99
gMVP		1.0
Mutation Taster		=0/100	disease causing

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

Other links and lift over

dbSNP: rs794727855; hg19: chr21-47535942;