Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong
The NM_000251.3(MSH2):c.961_1006delACTGGCTCTCAGTCTCTGGCTGCCTTGCTGAATAAGTGTAAAACCC(p.Thr321LeufsTer21) variant causes a frameshift change. 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 2-47416311-ACCACTGGCTCTCAGTCTCTGGCTGCCTTGCTGAATAAGTGTAAAAC-A is Pathogenic according to our data. Variant chr2-47416311-ACCACTGGCTCTCAGTCTCTGGCTGCCTTGCTGAATAAGTGTAAAAC-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 439197.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. Loss-of-function variants in MSH2 are known to be pathogenic (PMID: 15849733, 24362816). This variant has not been reported in the literature in individuals with MSH2-related disease. ClinVar contains an entry for this variant (Variation ID: 439197). This variant is not present in population databases (ExAC no frequency). This sequence change creates a premature translational stop signal (p.Thr321Leufs*21) in the MSH2 gene. It is expected to result in an absent or disrupted protein product. -