Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_000251.3(MSH2):c.87_90delGCCG(p.Thr31ProfsTer32) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★★).
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 does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 376 pathogenic variants in the truncated region.
PM2
Very rare variant in population databases, with high coverage;
PP5
Variant 2-47403277-AGCCG-A is Pathogenic according to our data. Variant chr2-47403277-AGCCG-A is described in ClinVar as [Pathogenic]. Clinvar id is 408477.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
Review Status: criteria provided, single submitter
Collection Method: clinical testing
For these reasons, this variant has been classified as Pathogenic. While this particular variant has not been reported in the literature, truncating variants in MSH2 are known to be pathogenic (PMID: 15849733, 24362816). This sequence change deletes 4 nucleotides from exon 1 of the MSH2 mRNA (c.87_90delGCCG), causing a frameshift at codon 31. This creates a premature translational stop signal (p.Thr31Profs*32) and is expected to result in an absent or disrupted protein product. -