7-45000364-G-A
Variant summary
Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_031443.4(CCM2):c.30+1G>A variant causes a splice donor, intron change involving the alteration of a non-conserved nucleotide. 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 predict no significant impact on normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).
Frequency
Consequence
NM_031443.4 splice_donor, intron
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Pathogenic. Variant got 18 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes Cov.: 24
GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0AN: 1156554Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0AN XY: 558626
GnomAD4 genome Cov.: 24
ClinVar
Submissions by phenotype
not provided Pathogenic:3
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This variant is expected to severely impact normal RNA splicing, and consequently, protein structure and/or function. This variant has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). This variant has been identified in at least one individual with clinical features associated with this gene. -
Canonical splice site variant in a gene for which loss-of-function is a known mechanism of disease; Not observed in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 19088124, 15122722, 14624391, 17160895, 34426522, 18300272) -
Cerebral cavernous malformation 2 Pathogenic:2
The CCM2 c.30+1G>A variant (rs1562848479, ClinVar Variation ID: 590655) is reported in the literature in individuals affected with cerebral cavernous malformations (Stahl 2008, Verlaan 2004). This variant is absent from the Genome Aggregation Database (v2.1.1), indicating it is not a common polymorphism. This variant disrupts the canonical splice donor site of intron 1, which is likely to negatively impact gene function. In vitro functional analysis by immunohistochemistry shows localized loss of CCM2 expression in the cavernous endothelial cells (Pagenstecher 2009). Based on available information, this variant is considered to be pathogenic. References: Pagenstecher A et al. A two-hit mechanism causes cerebral cavernous malformations: complete inactivation of CCM1, CCM2 or CCM3 in affected endothelial cells. Hum Mol Genet. 2009 Mar 1;18(5):911-8. PMID: 19088124. Stahl S et al. Novel CCM1, CCM2, and CCM3 mutations in patients with cerebral cavernous malformations: in-frame deletion in CCM2 prevents formation of a CCM1/CCM2/CCM3 protein complex. Hum Mutat. 2008 May;29(5):709-17. PMID: 18300272. Verlaan DJ et al. CCM2 mutations account for 13% of cases in a large collection of kindreds with hereditary cavernous malformations. Ann Neurol. 2004 May;55(5):757-8. PMID: 15122722. -
This sequence change affects a donor splice site in intron 1 of the CCM2 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in CCM2 are known to be pathogenic (PMID: 18300272, 24689081). This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individual(s) with cerebral cavernous malformations (PMID: 15122722, 19088124). This variant is also known as IVS+1G>A. ClinVar contains an entry for this variant (Variation ID: 590655). Algorithms developed to predict the effect of variants on gene product structure and function are not available or were not evaluated for this variant. Experimental studies have shown that disruption of this splice site affects CCM2 function (PMID: 19088124). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at