6-75103800-C-T

Variant names:

• chr6-75103800-C-T
• rs1554168599
• NM_004370.6:c.8276G>A

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_004370.6(COL12A1):​c.8276G>A​(p.Gly2759Asp) variant causes a missense change. 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 Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: COL12A1 NM_004370.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.39

Genes affected

COL12A1 (HGNC:2188): (collagen type XII alpha 1 chain) This gene encodes the alpha chain of type XII collagen, a member of the FACIT (fibril-associated collagens with interrupted triple helices) collagen family. Type XII collagen is a homotrimer found in association with type I collagen, an association that is thought to modify the interactions between collagen I fibrils and the surrounding matrix. Alternatively spliced transcript variants encoding different isoforms have been identified. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.986

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL12A1	NM_004370.6	c.8276G>A	p.Gly2759Asp	missense_variant	Exon 55 of 66	ENST00000322507.13	NP_004361.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL12A1	ENST00000322507.13	c.8276G>A	p.Gly2759Asp	missense_variant	Exon 55 of 66	1	NM_004370.6	ENSP00000325146.8

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Bethlem myopathy 2;C4225314:Ullrich congenital muscular dystrophy 2 Uncertain:1

Jul 04, 2019

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine with aspartic acid at codon 2759 of the COL12A1 protein (p.Gly2759Asp). The glycine residue is highly conserved and there is a moderate physicochemical difference between glycine and aspartic acid. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a COL12A1-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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), and missense variants at these glycine residues in COL12A1 are more frequently observed in individuals with disease than in the general population (PMID: 10612821). However, the clinical significance of this observation remains uncertain since only a limited number of affected individuals have been described to date. In summary, this variant is a novel missense change affecting a residue that is critical for protein structure, stability and function. However, the available evidence is currently insufficient to determine its role 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	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.51
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.47	.;T;D;.;.;.
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.95
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D;D;D;D;D;D
M_CAP	Pathogenic	0.47	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Pathogenic	3.8	.;.;H;.;.;.
PrimateAI	Pathogenic	0.90	D
PROVEAN	Pathogenic	-5.7	D;.;D;D;D;D
REVEL	Pathogenic	0.94
Sift	Uncertain	0.0020	D;.;D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D;D;D
Polyphen		1.0	.;.;D;D;.;.
Vest4		0.75, 0.87, 0.89, 0.91, 0.91
MutPred		0.92		.;.;Gain of relative solvent accessibility (P = 0.0023);.;.;Gain of relative solvent accessibility (P = 0.0023);
MVP		0.95
MPC		1.6
ClinPred		0.99	D
GERP RS		5.5
Varity_R		0.99
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs1554168599; hg19: chr6-75813516;