ClinVar Genomic variation as it relates to human health

This variant is denoted MSH6 c.2693C>G at the cDNA level, p.Pro898Arg (P898R) at the protein level, and results in the change of a Proline to an Arginine (CCT>CGT). This variant has not, to our knowledge, been published in the literature as a pathogenic or benign germline variant. MSH6 Pro898Arg was not observed in large population cohorts (Lek 2016). MSH6 Pro898Arg is located in the lever domain (Warren 2007, Kansikas 2011). In silico analysis, which includes protein predictors and evolutionary conservation, supports a deleterious effect. Based on currently available evidence, it is unclear whether MSH6 Pro898Arg is a pathogenic or benign variant. We consider it to be a variant of uncertain significance.

This sequence change replaces proline, which is neutral and non-polar, with arginine, which is basic and polar, at codon 898 of the MSH6 protein (p.Pro898Arg). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with MSH6-related conditions. ClinVar contains an entry for this variant (Variation ID: 234896). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt MSH6 protein function with a negative predictive value of 95%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance.

The p.P898R variant (also known as c.2693C>G), located in coding exon 4 of the MSH6 gene, results from a C to G substitution at nucleotide position 2693. The proline at codon 898 is replaced by arginine, an amino acid with dissimilar properties. This alteration was detected in a cohort of 1663 Brazilian breast cancer patients who underwent hereditary multigene panel testing (Guindalini RSC et al. Sci Rep, 2022 Mar;12:4190). This amino acid position is well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear.

Variant summary: MSH6 c.2693C>G (p.Pro898Arg) results in a non-conservative amino acid change located in the DNA mismatch repair protein MutS, core domain (IPR007696) of the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 250594 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.2693C>G in individuals affected with Hereditary Nonpolyposis Colorectal Cancer/Lynch syndrome and no experimental evidence demonstrating its impact on protein function have been reported. Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance.

This missense variant replaces proline with arginine at codon 898 of the MSH6 protein. Computational prediction is inconclusive regarding the impact of this variant on protein structure and function (internally defined REVEL score threshold 0.5 < inconclusive < 0.7, PMID: 27666373). To our knowledge, functional studies have not been reported for this variant. This variant has not been reported in individuals affected with MSH6-related disorders in the literature. This variant has not been identified 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 missense variant replaces proline with arginine at codon 898 of the MSH6 protein. Computational prediction tools and conservation analyses are inconclusive regarding the impact of this variant on the protein function. Computational splicing tools suggest that this variant may not impact RNA splicing. To our knowledge, functional assays have not been performed for this variant nor has this variant been reported in individuals affected with hereditary cancer in the literature. This variant has not been identified in the general population by the Genome Aggregation Database (gnomAD). 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.