21-46126166-G-C

Variant names:

• chr21-46126166-G-C
• rs75120695
• NM_001849.4:c.2351G>C

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PM5 PP3_Moderate

The NM_001849.4(COL6A2):​c.2351G>C​(p.Arg784Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,208 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. R784H) has been classified as Pathogenic.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
• Consequence: COL6A2 NM_001849.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 1.40

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a domain VWFA 2 (size 190) in uniprot entity CO6A2_HUMAN there are 17 pathogenic changes around while only 5 benign (77%) 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 chr21-46126166-G-A is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.864

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL6A2	NM_001849.4	c.2351G>C	p.Arg784Pro	missense_variant	Exon 26 of 28	ENST00000300527.9	NP_001840.3
COL6A2	NM_058174.3	c.2351G>C	p.Arg784Pro	missense_variant	Exon 26 of 28		NP_478054.2
COL6A2	NM_058175.3	c.2351G>C	p.Arg784Pro	missense_variant	Exon 26 of 28		NP_478055.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL6A2	ENST00000300527.9	c.2351G>C	p.Arg784Pro	missense_variant	Exon 26 of 28	1	NM_001849.4	ENSP00000300527.4
COL6A2	ENST00000397763.6	c.2351G>C	p.Arg784Pro	missense_variant	Exon 26 of 28	5		ENSP00000380870.1
COL6A2	ENST00000409416.6	c.2351G>C	p.Arg784Pro	missense_variant	Exon 25 of 27	5		ENSP00000387115.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152208 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 38

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152208 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74352

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Bethlem myopathy 1A Uncertain:1

May 10, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with COL6A2-related conditions. ClinVar contains an entry for this variant (Variation ID: 290250). This variant is not present in population databases (ExAC no frequency). This sequence change replaces arginine with proline at codon 784 of the COL6A2 protein (p.Arg784Pro). The arginine residue is weakly conserved and there is a moderate physicochemical difference between arginine and proline. 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. -

not provided Uncertain:1

May 05, 2017

Eurofins Ntd Llc (ga)

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Uncertain	0.12	D
BayesDel_noAF	Uncertain	-0.070
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Benign	0.24	T;.;.;.
Eigen	Benign	-0.11
Eigen_PC	Benign	-0.072
FATHMM_MKL	Uncertain	0.82	D
LIST_S2	Uncertain	0.91	D;D;.;D
M_CAP	Uncertain	0.26	D
MetaRNN	Pathogenic	0.86	D;D;D;D
MetaSVM	Benign	-0.62	T
MutationAssessor	Benign	0.66	N;N;N;N
PrimateAI	Benign	0.40	T
PROVEAN	Benign	-1.4	N;N;N;N
REVEL	Uncertain	0.53
Sift	Benign	0.27	T;T;T;T
Sift4G	Benign	0.27	T;T;T;T
Polyphen		0.98	D;P;P;P
Vest4		0.65
MutPred		0.74		Loss of sheet (P = 0.0357);Loss of sheet (P = 0.0357);Loss of sheet (P = 0.0357);Loss of sheet (P = 0.0357);
MVP		0.83
MPC		0.62
ClinPred		0.70	D
GERP RS		2.8
Varity_R		0.82
gMVP		0.91

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: rs75120695; hg19: chr21-47546080;