21-46111534-G-A

Position:

• chr21-46111534-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001849.4(COL6A2):​c.58G>A​(p.Ala20Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,460,730 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: COL6A2 NM_001849.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.154

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]

LOC124905043 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.24754664).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
COL6A2	NM_001849.4	c.58G>A	p.Ala20Thr	missense_variant	2/28	ENST00000300527.9	NP_001840.3
COL6A2	NM_058174.3	c.58G>A	p.Ala20Thr	missense_variant	2/28	ENST00000397763.6	NP_478054.2
LOC124905043	XR_007067910.1	n.498C>T		non_coding_transcript_exon_variant	1/2
COL6A2	NM_058175.3	c.58G>A	p.Ala20Thr	missense_variant	2/28		NP_478055.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
COL6A2	ENST00000300527.9	c.58G>A	p.Ala20Thr	missense_variant	2/28	1	NM_001849.4	ENSP00000300527	P1
COL6A2	ENST00000397763.6	c.58G>A	p.Ala20Thr	missense_variant	2/28	5	NM_058174.3	ENSP00000380870
COL6A2	ENST00000409416.6	c.58G>A	p.Ala20Thr	missense_variant	1/27	5		ENSP00000387115
COL6A2	ENST00000436769.5	c.58G>A	p.Ala20Thr	missense_variant	2/3	2		ENSP00000390418

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1460730 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 726666

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 30

Alfa AF: 0.0000468 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Bethlem myopathy 1A Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 02, 2019

This sequence change replaces alanine with threonine at codon 20 of the COL6A2 protein (p.Ala20Thr). The alanine residue is moderately conserved and there is a small physicochemical difference between alanine and threonine. 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. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The threonine amino acid residue is found in multiple mammalian species, suggesting that this missense change does not adversely affect protein function. These predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with COL6A2-related conditions. This variant is not present in population databases (ExAC no frequency). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.23
BayesDel_addAF	Benign	-0.025	T
BayesDel_noAF	Benign	-0.27
CADD	Benign	19
DANN	Benign	0.78
DEOGEN2	Benign	0.23	T;.;T;.;.
Eigen	Benign	-0.31
Eigen_PC	Benign	-0.28
FATHMM_MKL	Benign	0.53	D
LIST_S2	Benign	0.82	T;T;T;.;T
M_CAP	Uncertain	0.17	D
MetaRNN	Benign	0.25	T;T;T;T;T
MetaSVM	Benign	-0.38	T
MutationAssessor	Uncertain	2.1	M;M;.;M;M
MutationTaster	Benign	0.99	D;D;D;D;D
PrimateAI	Uncertain	0.48	T
PROVEAN	Benign	-1.0	N;N;N;N;N
REVEL	Benign	0.20
Sift	Uncertain	0.014	D;D;D;D;D
Sift4G	Benign	0.15	T;T;D;T;T
Polyphen		0.079	B;B;.;B;B
Vest4		0.16
MutPred		0.35		Gain of sheet (P = 0.0344);Gain of sheet (P = 0.0344);Gain of sheet (P = 0.0344);Gain of sheet (P = 0.0344);Gain of sheet (P = 0.0344);
MVP		0.85
MPC		0.13
ClinPred		0.24	T
GERP RS		4.2
Varity_R		0.097
gMVP		0.41

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: rs2078398153; hg19: chr21-47531448;