MSH2 NM_000251.3:c.182A>C, Gln61Pro

This missense variant replaces glutamine with proline at codon 61 of the MSH2 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). This variant does not impact MSH2 function in a 6-thioguanine sensitivity assay in haploid human cells (internally defined LOF score threshold <= -1.32, PMID: 33357406). Additional functional studies have reported this variant protein to be functional in yeast mutator and protein binding assays (PMID: 17720936, 20176959).This variant has been reported in an individual affected with ovarian and colorectal cancer (PMID: 25133505), and in a family affected with bladder cancer (PMID: 34964002). This variant has been identified in 1/232376 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance.

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com.

Variant summary: MSH2 c.182A>C (p.Gln61Pro) results in a non-conservative amino acid change located in the N-terminal domain (IPR007695) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4.3e-06 in 232376 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.182A>C has been reported in the literature in an individual affected with ovarian cancer and colorectal cancer who fulfilled at least one of the revised Bethesda guidelines and in affected individuals undergoing genetic testing for hereditary cancers (e.g. Tsaousis_2019, Germani_2020, Pemov_2021). These reports do not provide unequivocal conclusions about association of the variant with Lynch Syndrome. Functional studies examining the variant in a yeast model system and using a DNA mismatch repair proficiency screen showed no damaging effect of this variant (Gammie_2007, Jia_2021). The following publications have been ascertained in the context of this evaluation (PMID: 17720936, 32957588, 33357406, 25133505, 34964002, 31159747). Six submitters have provided clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as either VUS (n=3) or likely benign (n=3). Based on the evidence outlined above, the variant was classified as uncertain significance.

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity.

This missense variant replaces glutamine with proline at codon 61 of the MSH2 protein. Computational prediction suggests that this variant may have deleterious impact on protein structure and function (internally defined REVEL score threshold >= 0.7, PMID: 27666373). This variant does not impact MSH2 function in a 6-thioguanine sensitivity assay in haploid human cells (internally defined LOF score threshold <= -1.32, PMID: 33357406). Additional functional studies have reported this variant protein to be functional in yeast mutator and protein binding assays (PMID: 17720936, 20176959).This variant has been reported in an individual affected with ovarian and colorectal cancer (PMID: 25133505), and in a family affected with bladder cancer (PMID: 34964002). This variant has been identified in 1/232376 chromosomes in the general population by the Genome Aggregation Database (gnomAD). The available evidence is insufficient to determine the role of this variant in disease conclusively. Therefore, this variant is classified as a Variant of Uncertain Significance.