2-188994235-G-C

Variant names:

• chr2-188994235-G-C
• rs1060500194
• NM_000090.4:c.1196G>C

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1 PM2 PP2 PP3 PP5_Moderate

The NM_000090.4(COL3A1):​c.1196G>C​(p.Gly399Ala) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 15/24 in silico tools predict a damaging outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. G399G) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 32)
• Consequence: COL3A1 NM_000090.4 missense, splice_region
• Scores: Splicing: ADA: 0.9845
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 10.0
• Publications: 0 publications found

Genes affected

COL3A1 (HGNC:2201): (collagen type III alpha 1 chain) This gene encodes the pro-alpha1 chains of type III collagen, a fibrillar collagen that is found in extensible connective tissues such as skin, lung, uterus, intestine and the vascular system, frequently in association with type I collagen. Mutations in this gene are associated with Ehlers-Danlos syndrome type IV, and with aortic and arterial aneurysms. [provided by R. Dalgleish, Feb 2008]

COL3A1 Gene-Disease associations (from GenCC):

• autosomal dominant Ehlers-Danlos syndrome, vascular type

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, PanelApp Australia, Labcorp Genetics (formerly Invitae), Laboratory for Molecular Medicine, Genomics England PanelApp
• Ehlers-Danlos syndrome, vascular type

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
• polymicrogyria with or without vascular-type Ehlers-Danlos syndrome

  Inheritance: AR Classification: STRONG Submitted by: PanelApp Australia, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 9 uncertain in NM_000090.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the COL3A1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 495 curated pathogenic missense variants (we use a threshold of 10). The gene has 19 curated benign missense variants. Gene score misZ: 4.0879 (above the threshold of 3.09). Trascript score misZ: 4.5995 (above the threshold of 3.09). GenCC associations: The gene is linked to Ehlers-Danlos syndrome, vascular type, polymicrogyria with or without vascular-type Ehlers-Danlos syndrome, autosomal dominant Ehlers-Danlos syndrome, vascular type.
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• PP5: Variant 2-188994235-G-C is Pathogenic according to our data. Variant chr2-188994235-G-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 404290.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL3A1	NM_000090.4	c.1196G>C	p.Gly399Ala	missense_variant, splice_region_variant	Exon 18 of 51	ENST00000304636.9	NP_000081.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL3A1	ENST00000304636.9	c.1196G>C	p.Gly399Ala	missense_variant, splice_region_variant	Exon 18 of 51	1	NM_000090.4	ENSP00000304408.4
COL3A1	ENST00000450867.2	c.1097G>C	p.Gly366Ala	missense_variant, splice_region_variant	Exon 17 of 50	1		ENSP00000415346.2
COL3A1	ENST00000713745.1	c.1196G>C	p.Gly399Ala	missense_variant, splice_region_variant	Exon 18 of 49			ENSP00000519049.1
COL3A1	ENST00000713744.1	c.1196G>C	p.Gly399Ala	missense_variant, splice_region_variant	Exon 18 of 49			ENSP00000519048.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Ehlers-Danlos syndrome, type 4 Pathogenic:1

Sep 13, 2018

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, this variant is a novel missense change affecting a residue crucial for protein structure and stability. Although additional genetic data will be necessary to further confirm pathogenicity for this variant, glycine substitutions located in COL3A1 TH domains are likely deleterious. For these reasons, this variant has been classified as Likely Pathogenic. Glycine residues within the triple helix (TH) domain are important for fibrillar collagens structure and stability (PMID: 7695699, 8218237, 19344236). In the case of COL3A1 the majority of the missense substitutions at the triple helix domain affect glycine residues (PMID: 24922459, 25758994). This sequence change replaces glycine with alanine at codon 399 of the COL3A1 protein (p.Gly399Ala). The glycine residue is highly conserved and there is a small physicochemical difference between glycine and alanine. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a COL3A1-related disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.81
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	29
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.96	D;.
Eigen	Pathogenic	0.98
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Pathogenic	0.97	D;D
M_CAP	Pathogenic	0.96	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	4.1	H;H
PhyloP100		10
PrimateAI	Pathogenic	0.89	D
PROVEAN	Pathogenic	-5.2	D;D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;.
Vest4		0.89
MutPred		0.98		Loss of catalytic residue at G399 (P = 0.0055);Loss of catalytic residue at G399 (P = 0.0055);
MVP		0.98
MPC		0.68
ClinPred		1.0	D
GERP RS		5.6
Varity_R		0.92
gMVP		1.0
Mutation Taster		=2/98	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.98
dbscSNV1_RF	Pathogenic	0.79
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

Other links and lift over

dbSNP: rs1060500194; hg19: chr2-189858961;