rs1064795935

Variant names:

• chr13-110181389-C-T
• rs1064795935
• NM_001845.6:c.2096G>A

Variant summary

Our verdict is Pathogenic. Variant got 13 ACMG points: 13P and 0B. PM2 PP2 PP3_Moderate PP5_Very_Strong

The NM_001845.6(COL4A1):​c.2096G>A​(p.Gly699Asp) variant causes a missense, splice region change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: COL4A1 NM_001845.6 missense, splice_region
• Scores: Splicing: ADA: 0.9997
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 4.25

Genes affected

COL4A1 (HGNC:2202): (collagen type IV alpha 1 chain) This gene encodes a type IV collagen alpha protein. Type IV collagen proteins are integral components of basement membranes. This gene shares a bidirectional promoter with a paralogous gene on the opposite strand. The protein consists of an amino-terminal 7S domain, a triple-helix forming collagenous domain, and a carboxy-terminal non-collagenous domain. It functions as part of a heterotrimer and interacts with other extracellular matrix components such as perlecans, proteoglycans, and laminins. In addition, proteolytic cleavage of the non-collagenous carboxy-terminal domain results in a biologically active fragment known as arresten, which has anti-angiogenic and tumor suppressor properties. Mutations in this gene cause porencephaly, cerebrovascular disease, and renal and muscular defects. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Dec 2014]

ACMG classification

Verdict is Pathogenic. Variant got 13 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the COL4A1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 194 curated pathogenic missense variants (we use a threshold of 10). The gene has 77 curated benign missense variants. Gene score misZ: 3.0194 (below the threshold of 3.09). Trascript score misZ: 4.972 (above the threshold of 3.09). GenCC associations: The gene is linked to brain small vessel disease 1 with or without ocular anomalies, pontine autosomal dominant microangiopathy with leukoencephalopathy, muscular dystrophy-dystroglycanopathy, type A, microangiopathy and leukoencephalopathy, pontine, autosomal dominant, familial porencephaly, autosomal dominant familial hematuria-retinal arteriolar tortuosity-contractures syndrome, retinal arterial tortuosity.
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• PP5: Variant 13-110181389-C-T is Pathogenic according to our data. Variant chr13-110181389-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 422683.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
COL4A1	NM_001845.6	c.2096G>A	p.Gly699Asp	missense_variant, splice_region_variant	Exon 29 of 52	ENST00000375820.10	NP_001836.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
COL4A1	ENST00000375820.10	c.2096G>A	p.Gly699Asp	missense_variant, splice_region_variant	Exon 29 of 52	1	NM_001845.6	ENSP00000364979.4
COL4A1	ENST00000649738.1	n.2226G>A		splice_region_variant, non_coding_transcript_exon_variant	Exon 29 of 31

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Pathogenic:1

Apr 11, 2017

Ambry Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Pathogenic:1

May 29, 2024

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Identified in patients with features consistent with COL4A1-related small vessel disease with multiple anomalies referred for genetic testing at GeneDx and in published literature, including multiple apparently de novo occurrences (PMID: 30413629, 32732225); Affects a glycine residue in a Gly-X-Y motif in the triple helical region of the COL4A1 gene, where the majority of pathogenic missense variants occur, and is predicted to disrupt normal protein folding and function (HGMD; PMID: 22522439, 23225343); Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 35699195, 30413629, 32732225, 31628766, 22522439, 23225343) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.57
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.91	D
Eigen	Pathogenic	0.82
Eigen_PC	Uncertain	0.66
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.87	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	0.95	D
MutationAssessor	Pathogenic	4.9	H
PrimateAI	Uncertain	0.77	T
PROVEAN	Pathogenic	-5.6	D
REVEL	Pathogenic	0.94
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.92
MutPred		0.75		Gain of catalytic residue at P694 (P = 0);
MVP		0.98
MPC		0.63
ClinPred		1.0	D
GERP RS		4.9
Varity_R		0.97
gMVP		1.0

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.96
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: rs1064795935; hg19: chr13-110833736;