chr21-46118626-C-A

Variant names:

• chr21-46118626-C-A
• rs144801620
• NM_001849.4:c.1129C>A

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_001849.4(COL6A2):​c.1129C>A​(p.Arg377Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000124 in 1,612,378 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R377C) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 34)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: COL6A2 NM_001849.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.924
• Publications: 2 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: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL6A2	NM_001849.4	c.1129C>A	p.Arg377Ser	missense_variant	Exon 13 of 28	ENST00000300527.9	NP_001840.3
COL6A2	NM_058174.3	c.1129C>A	p.Arg377Ser	missense_variant	Exon 13 of 28	ENST00000397763.6	NP_478054.2
COL6A2	NM_058175.3	c.1129C>A	p.Arg377Ser	missense_variant	Exon 13 of 28		NP_478055.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL6A2	ENST00000300527.9	c.1129C>A	p.Arg377Ser	missense_variant	Exon 13 of 28	1	NM_001849.4	ENSP00000300527.4
COL6A2	ENST00000397763.6	c.1129C>A	p.Arg377Ser	missense_variant	Exon 13 of 28	5	NM_058174.3	ENSP00000380870.1
COL6A2	ENST00000409416.6	c.1129C>A	p.Arg377Ser	missense_variant	Exon 12 of 27	5		ENSP00000387115.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152216 Hom.: 0 Cov.: 34

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460162 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 726350

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44686

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26108

East Asian (EAS) AF: 0.00 AC: 0 AN: 39684

South Asian (SAS) AF: 0.00 AC: 0 AN: 86114

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52148

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111828

Other (OTH) AF: 0.00 AC: 0 AN: 60346

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152216 Hom.: 0 Cov.: 34 AF XY: 0.0000134 AC XY: 1 AN XY: 74364

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.0000241 AC: 1 AN: 41466

American (AMR) AF: 0.00 AC: 0 AN: 15290

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5186

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68026

Other (OTH) AF: 0.00 AC: 0 AN: 2092

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.66
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.040
CADD	Pathogenic	26
DANN	Uncertain	0.99
DEOGEN2	Benign	0.20	T;.;.;.
Eigen	Benign	0.0027
Eigen_PC	Benign	0.12
LIST_S2	Uncertain	0.92	D;D;.;D
M_CAP	Uncertain	0.26	D
MetaRNN	Uncertain	0.70	D;D;D;D
MetaSVM	Uncertain	0.26	D
MutationAssessor	Benign	-0.010	N;N;N;N
PhyloP100		0.92
PrimateAI	Uncertain	0.51	T
PROVEAN	Benign	-2.2	N;N;N;N
Sift	Benign	0.15	T;T;T;T
Sift4G	Benign	0.14	T;T;T;T
Vest4		0.64
ClinPred		0.93	D
GERP RS		4.7
Varity_R		0.49
gMVP		0.54
Mutation Taster		=30/70	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs144801620; hg19: chr21-47538540;