21-45981894-G-T

Position:

• chr21-45981894-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 2P and 1B. PM2 BP4

The NM_001848.3(COL6A1):​c.44G>T​(p.Cys15Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000275 in 1,454,048 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts 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. C15R) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 29)
  • Exomes 𝑓: 0.0000028 (0 hom.)
• Consequence: COL6A1 NM_001848.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.36

Genes affected

COL6A1 (HGNC:2211): (collagen type VI alpha 1 chain) The collagens are a superfamily of proteins that play a role in maintaining the integrity of various tissues. Collagens are extracellular matrix proteins and have a triple-helical domain as their common structural element. Collagen VI is a major structural component of microfibrils. The basic structural unit of collagen VI is a heterotrimer of the alpha1(VI), alpha2(VI), and alpha3(VI) chains. The alpha2(VI) and alpha3(VI) chains are encoded by the COL6A2 and COL6A3 genes, respectively. The protein encoded by this gene is the alpha 1 subunit of type VI collagen (alpha1(VI) chain). Mutations in the genes that code for the collagen VI subunits result in the autosomal dominant disorder, Bethlem myopathy. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 1 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.3582803).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
COL6A1	NM_001848.3	c.44G>T	p.Cys15Phe	missense_variant	1/35	ENST00000361866.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
COL6A1	ENST00000361866.8	c.44G>T	p.Cys15Phe	missense_variant	1/35	1	NM_001848.3	P1

Frequencies

GnomAD3 genomes Cov.: 29

GnomAD4 exome AF: 0.00000275 AC: 4 AN: 1454048 Hom.: 0 Cov.: 33 AF XY: 0.00000415 AC XY: 3 AN XY: 722930

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000254

Gnomad4 SAS exome AF: 0.0000353

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 29

ExAC AF: 0.00000834 AC: 1

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

Apr 24, 2022

This sequence change replaces cysteine, which is neutral and slightly polar, with phenylalanine, which is neutral and non-polar, at codon 15 of the COL6A1 protein (p.Cys15Phe). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with COL6A1-related conditions. 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 COL6A1 protein function. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.076
BayesDel_addAF	Uncertain	0.12	D
BayesDel_noAF	Uncertain	-0.060
CADD	Benign	18
DANN	Benign	0.95
DEOGEN2	Benign	0.41	T;T
Eigen	Benign	-0.040
Eigen_PC	Benign	-0.035
FATHMM_MKL	Benign	0.47	N
LIST_S2	Benign	0.36	T;T
M_CAP	Pathogenic	0.30	D
MetaRNN	Benign	0.36	T;T
MetaSVM	Uncertain	-0.23	T
MutationAssessor	Uncertain	2.1	M;.
MutationTaster	Benign	0.84	N
PrimateAI	Uncertain	0.76	T
PROVEAN	Benign	-2.2	N;.
REVEL	Uncertain	0.49
Sift	Uncertain	0.0060	D;.
Sift4G	Uncertain	0.0020	D;D
Polyphen		0.98	D;.
Vest4		0.28
MutPred		0.45		Loss of catalytic residue at W16 (P = 0.0842);Loss of catalytic residue at W16 (P = 0.0842);
MVP		0.52
MPC		0.34
ClinPred		0.48	T
GERP RS		2.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.6
Varity_R		0.41
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: rs776678940; hg19: chr21-47401808;