rs113994112

Positions:

• chr13-110170583-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM2 PP2 PP3_Strong PP5_Moderate

The NM_001845.6(COL4A1):​c.3706G>A​(p.Gly1236Arg) 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. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: COL4A1 NM_001845.6 missense
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2 O:1
• Conservation: PhyloP100: 7.28

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 Likely_pathogenic. Variant got 9 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), COL4A1. . Gene score misZ 3.0194 (greater than the threshold 3.09). Trascript score misZ 4.972 (greater than threshold 3.09). GenCC has associacion of gene with 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: MetaRNN computational evidence supports a deleterious effect, 0.981
• PP5: Variant 13-110170583-C-T is Pathogenic according to our data. Variant chr13-110170583-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 17412.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr13-110170583-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
COL4A1	NM_001845.6	c.3706G>A	p.Gly1236Arg	missense_variant	42/52	ENST00000375820.10	NP_001836.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
COL4A1	ENST00000375820.10	c.3706G>A	p.Gly1236Arg	missense_variant	42/52	1	NM_001845.6	ENSP00000364979.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

Brain small vessel disease 1 with or without ocular anomalies Pathogenic:1 Other:1

not provided, no classification provided	literature only	GeneReviews	-	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	May 20, 2005	- -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

GeneDx

May 17, 2022

Identified in 3 family members with porencephaly (Gould et al., 2005; van der Knapp et al., 2006); Not observed in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Missense variants at the same and in nearby residues reported in the Human Gene Mutation Database in individuals with COL4A1-related disorders (HGMD); 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 (Stenson et al., 2014; Weng et al., 2012; Yoneda et al., 2013); This variant is associated with the following publications: (PMID: 24077912, 22522439, 23225343, 6428250, 16374828, 15905400) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	28
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.84	D
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.87
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.96	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	0.97	D
MutationAssessor	Pathogenic	4.4	H
PrimateAI	Pathogenic	0.85	D
PROVEAN	Pathogenic	-6.3	D
REVEL	Pathogenic	0.96
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.0020	D
Polyphen		1.0	D
Vest4		0.98
MutPred		0.75		Gain of catalytic residue at K1235 (P = 0.0055);
MVP		0.98
MPC		1.3
ClinPred		1.0	D
GERP RS		5.1
Varity_R		0.21
gMVP		1.0

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

Publications

LitVar

Other links and lift over

dbSNP: rs113994112; hg19: chr13-110822930;