Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2PM4
The NM_000251.3(MSH2):c.167_184delAGGTGTTCAAGACCCAGG(p.Glu56_Gln61del) variant causes a disruptive inframe deletion 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 Uncertain significance (★).
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]
Review Status: criteria provided, single submitter
Collection Method: clinical testing
In summary, this variant is a novel in-frame deletion  with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Experimental studies and prediction algorithms are not available for this variant, and the functional significance of the deleted amino acid(s) is currently unknown. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a MSH2-related disease. This sequence change deletes 18 nucleotides from exon 1 of the MSH2 mRNA (c.167_184delAGGTGTTCAAGACCCAGG). This leads to the deletion of 6 amino acid residue(s) in the MSH2 protein (p.Glu56_Gln61del) but otherwise preserves the integrity of the reading frame. -