Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2
The ENST00000265849.12(PMS2):c.2278C>T(p.Pro760Ser) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000664 in 150,704 control chromosomes in the GnomAD database, with no homozygous occurrence. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P760L) has been classified 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]
Uncertain significance, criteria provided, single submitter
clinical testing
Labcorp Genetics (formerly Invitae), Labcorp
Sep 26, 2019
This sequence change replaces proline with serine at codon 760 of the PMS2 protein (p.Pro760Ser). The proline residue is moderately conserved and there is a moderate physicochemical difference between proline and serine. The frequency data for this variant in the population databases (ExAC) is considered unreliable due to the presence of homologous sequence, such as pseudogenes or paralogs, in the genome. This variant has not been reported in the literature in individuals with PMS2-related conditions. ClinVar contains an entry for this variant (Variation ID: 237905). 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. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). -
Uncertain significance, criteria provided, single submitter
clinical testing
Ambry Genetics
Mar 14, 2022
The p.P760S variant (also known as c.2278C>T), located in coding exon 14 of the PMS2 gene, results from a C to T substitution at nucleotide position 2278. The proline at codon 760 is replaced by serine, an amino acid with similar properties. This amino acid position is conserved. 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. -