Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_000251.3(MSH2):c.1077-66_1146del(p.Arg359fs) variant causes a frameshift, splice acceptor, splice region, intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.
MSH2 (HGNC:7325): (mutS homolog 2) This locus is frequently mutated in hereditary nonpolyposis colon cancer (HNPCC). When cloned, it was discovered to be a human homolog of the E. coli mismatch repair gene mutS, consistent with the characteristic alterations in microsatellite sequences (RER+ phenotype) found in HNPCC. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Apr 2012]
Verdict is Pathogenic. Variant got 18 ACMG points.
PVS1
Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
PM2
Very rare variant in population databases, with high coverage;
PP5
Variant 2-47429672-ACGTGCTTAGTTGATAAATTTTAATTTTATACTAAAATATTTTACATTAATTCAAGTTAATTTATTTCAGATTGAATTTAGTGGAAGCTTTTGTAGAAGATGCAGAATTGAGGCAGACTTTACAAGAAGATTTACTT-A is Pathogenic according to our data. Variant chr2-47429672-ACGTGCTTAGTTGATAAATTTTAATTTTATACTAAAATATTTTACATTAATTCAAGTTAATTTATTTCAGATTGAATTTAGTGGAAGCTTTTGTAGAAGATGCAGAATTGAGGCAGACTTTACAAGAAGATTTACTT-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 36563.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This variant results in the deletion of part of exon 7 (c.1077-66_1146del) of the MSH2 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 MSH2 are known to be pathogenic (PMID: 15849733, 24362816). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MSH2-related conditions. ClinVar contains an entry for this variant (Variation ID: 36563). This variant disrupts a region of the MSH2 protein in which other variant(s) (p.Arg359Ser) have been determined to be pathogenic (PMID: 11870161, 17165155, 17720936, 18781619). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -