Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2PP3_Moderate
The NM_000535.7(PMS2):c.716T>G(p.Leu239Arg) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).
PMS2 (HGNC:9122): (PMS1 homolog 2, mismatch repair system component) The protein encoded by this gene is a key component of the mismatch repair system that functions to correct DNA mismatches and small insertions and deletions that can occur during DNA replication and homologous recombination. This protein forms heterodimers with the gene product of the mutL homolog 1 (MLH1) gene to form the MutL-alpha heterodimer. The MutL-alpha heterodimer possesses an endonucleolytic activity that is activated following recognition of mismatches and insertion/deletion loops by the MutS-alpha and MutS-beta heterodimers, and is necessary for removal of the mismatched DNA. There is a DQHA(X)2E(X)4E motif found at the C-terminus of the protein encoded by this gene that forms part of the active site of the nuclease. Mutations in this gene have been associated with hereditary nonpolyposis colorectal cancer (HNPCC; also known as Lynch syndrome) and Turcot syndrome. [provided by RefSeq, Apr 2016]
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change replaces leucine with arginine at codon 239 of the PMS2 protein (p.Leu239Arg). The leucine residue is highly conserved and there is a moderate physicochemical difference between leucine and arginine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with PMS2-related disease. ClinVar contains an entry for this variant (Variation ID: 411058). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. 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. -
Review Status: criteria provided, single submitter
Collection Method: clinical testing
The p.L239R variant (also known as c.716T>G), located in coding exon 7 of the PMS2 gene, results from a T to G substitution at nucleotide position 716. The leucine at codon 239 is replaced by arginine, an amino acid with dissimilar properties. This alteration was identified in an individual diagnosed with a small bowel cancer at 45 (Wang Q et al. J Med Genet, 2020 07;57:487-499). This alteration was also identified in an individual diagnosed with colorectal cancer at 71. Immunohistochemistry on his tumor showed loss of expression of PMS2 (Schwartz A et al. Front Oncol, 2022 Aug;12:942741). This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -