rs1554166746

Variant names:

• chr6-75090193-G-A
• rs1554166746
• NM_004370.6:c.8858C>T

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_004370.6(COL12A1):​c.8858C>T​(p.Ala2953Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,834 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/22 in silico tools predict 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. A2953S) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: COL12A1 NM_004370.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.83
• Publications: 0 publications found

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]

COL12A1 Gene-Disease associations (from GenCC):

• Bethlem myopathy 2

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet
• Bethlem myopathy 2

  Inheritance: AD Classification: STRONG, LIMITED Submitted by: Ambry Genetics, Illumina, Genomics England PanelApp
• Ullrich congenital muscular dystrophy 2

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)
• Bethlem myopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Ullrich congenital muscular dystrophy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.21005091).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_004370.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL12A1	NM_004370.6	MANE Select	c.8858C>T	p.Ala2953Val	missense	Exon 63 of 66	NP_004361.3
	COL12A1	NM_001424113.1		c.8858C>T	p.Ala2953Val	missense	Exon 63 of 66	NP_001411042.1
	COL12A1	NM_001424114.1		c.8837C>T	p.Ala2946Val	missense	Exon 62 of 65	NP_001411043.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL12A1	ENST00000322507.13	TSL:1 MANE Select	c.8858C>T	p.Ala2953Val	missense	Exon 63 of 66	ENSP00000325146.8
	COL12A1	ENST00000345356.10	TSL:1	c.5366C>T	p.Ala1789Val	missense	Exon 48 of 51	ENSP00000305147.9
	COL12A1	ENST00000483888.6	TSL:5	c.8846C>T	p.Ala2949Val	missense	Exon 63 of 65	ENSP00000421216.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461834 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727222

African (AFR) AF: 0.0000299 AC: 1 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53388

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111996

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

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

Oct 23, 2016

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, this variant is a novel missense change with uncertain impact on protein function and splicing. It has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may alter RNA splicing, but this prediction has not been confirmed by published transcriptional studies. 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. This sequence change replaces alanine with valine at codon 2953 of the COL12A1 protein (p.Ala2953Val). The alanine residue is highly conserved and there is a small physicochemical difference between alanine and valine. 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 valine 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.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.091
BayesDel_addAF	Uncertain	0.021	T
BayesDel_noAF	Benign	-0.21
CADD	Benign	17
DANN	Uncertain	1.0
DEOGEN2	Benign	0.027	T
Eigen	Benign	-0.79
Eigen_PC	Benign	-0.74
FATHMM_MKL	Benign	0.42	N
LIST_S2	Benign	0.70	T
M_CAP	Benign	0.021	T
MetaRNN	Benign	0.21	T
MetaSVM	Benign	-0.68	T
MutationAssessor	Benign	0.61	N
PhyloP100		2.8
PrimateAI	Uncertain	0.51	T
PROVEAN	Benign	-1.3	N
REVEL	Benign	0.21
Sift	Benign	0.12	T
Sift4G	Benign	0.30	T
Polyphen		0.0020	B
Vest4		0.22
MutPred		0.49		Gain of catalytic residue at R2956 (P = 0.185)
MVP		0.52
MPC		0.48
ClinPred		0.17	T
GERP RS		1.7
Varity_R		0.046
gMVP		0.48
Mutation Taster		=85/15	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs1554166746; hg19: chr6-75799909;