2-188994550-G-T

Variant names:

• chr2-188994550-G-T
• rs886038952
• NM_000090.4:c.1303G>T

Variant summary

Our verdict is Pathogenic. The variant received 13 ACMG points: 13P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Moderate

The NM_000090.4(COL3A1):​c.1303G>T​(p.Gly435Cys) variant causes a missense 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. 13/22 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G435D) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: COL3A1 NM_000090.4 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.89
• 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: Pathogenic. The variant received 13 ACMG points.

• PM1: In a hotspot region, there are 6 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 6 uncertain in NM_000090.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-188994551-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 1769481.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• 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: MetaRNN computational evidence supports a deleterious effect, 0.995
• PP5: Variant 2-188994550-G-T is Pathogenic according to our data. Variant chr2-188994550-G-T is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 519606.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.1303G>T	p.Gly435Cys	missense_variant	Exon 19 of 51	ENST00000304636.9	NP_000081.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL3A1	ENST00000304636.9	c.1303G>T	p.Gly435Cys	missense_variant	Exon 19 of 51	1	NM_000090.4	ENSP00000304408.4
COL3A1	ENST00000450867.2	c.1204G>T	p.Gly402Cys	missense_variant	Exon 18 of 50	1		ENSP00000415346.2
COL3A1	ENST00000713745.1	c.1303G>T	p.Gly435Cys	missense_variant	Exon 19 of 49			ENSP00000519049.1
COL3A1	ENST00000713744.1	c.1303G>T	p.Gly435Cys	missense_variant	Exon 19 of 49			ENSP00000519048.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial thoracic aortic aneurysm and aortic dissection Pathogenic:1

Jul 21, 2020

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.G435C variant (also known as c.1303G>T), located in coding exon 19 of the COL3A1 gene, results from a G to T substitution at nucleotide position 1303. The glycine at codon 435 is replaced by cysteine, an amino acid with highly dissimilar properties, and is located in the triple-helical domain. The majority (approximately two-thirds) of COL3A1 mutations identified to date have involved the substitution of another amino acid for glycine within the triple-helical domain (Pepin MG et al. Genet Med. 2014;16(12):881-8; Frank M et al. Eur J Hum Genet. 2015;23(12):1657-64). Internal structural analysis indicates that this alteration disrupts the characteristic G-X-Y motif in the COL3A1 protein and inserts a bulky side chain into a sterically-constrained region (Bella J et al. Science. 1994;266:75-81; Hohenester E et al. Proc. Natl. Acad. Sci. U.S.A. 2008;105:18273-7; Ambry internal data). An alteration at the same amino acid position, p.G435D, was reported in a patient with vascular Ehlers-Danlos syndrome (Frank M et al. Eur J Hum Genet. 2015;23:1657-64). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the majority of available evidence to date, this variant is likely to be pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	30
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.91	D;.
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.97	D;D
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	1.0	D;D
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Pathogenic	4.7	H;H
PhyloP100		9.9
PrimateAI	Pathogenic	0.88	D
PROVEAN	Pathogenic	-7.4	D;D
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;.
Vest4		0.95
MutPred		0.99		Gain of methylation at K436 (P = 0.045);Gain of methylation at K436 (P = 0.045);
MVP		1.0
MPC		0.67
ClinPred		1.0	D
GERP RS		6.2
Varity_R		0.92
gMVP		1.0
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs886038952; hg19: chr2-189859276;