Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2
The NM_000535.7(PMS2):c.472A>T(p.Ser158Cys) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,459,438 control chromosomes in the GnomAD database, with no homozygous occurrence. 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
The p.S158C variant (also known as c.472A>T), located in coding exon 5 of the PMS2 gene, results from an A to T substitution at nucleotide position 472. The serine at codon 158 is replaced by cysteine, an amino acid with dissimilar properties. This amino acid position is well conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -
Aug 21, 2018
Color Diagnostics, LLC DBA Color Health
Significance: Uncertain significance
Review Status: criteria provided, single submitter
Review Status: criteria provided, single submitter
Collection Method: clinical testing
This sequence change replaces serine, which is neutral and polar, with cysteine, which is neutral and slightly polar, at codon 158 of the PMS2 protein (p.Ser158Cys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with biliary tract cancer (PMID: 36243179). ClinVar contains an entry for this variant (Variation ID: 490104). 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 PMS2 protein function with a negative predictive value of 80%. 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. -