Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2BP4_Strong
The NM_000535.7(PMS2):c.1450C>A(p.Pro484Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000186 in 1,613,972 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign 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 proline, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 484 of the PMS2 protein (p.Pro484Thr). This variant is present in population databases (rs752122569, gnomAD 0.01%). This missense change has been observed in individual(s) with colorectal cancer (PMID: 24362816, 28466842). ClinVar contains an entry for this variant (Variation ID: 484305). 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. 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.P484T variant (also known as c.1450C>A), located in coding exon 11 of the PMS2 gene, results from a C to A substitution at nucleotide position 1450. The proline at codon 484 is replaced by threonine, an amino acid with highly similar properties. This alteration, which the authors classify as a variant of uncertain significance, was identified in an Icelandic population genome-wide association study in both the colon cancer subject group and in controls (Haraldsdottir S et al. Nat Commun. 2017 May;8:14755). This alteration was also identified in an individual diagnosed with colorectal cancer at 27; IHC showed loss of expression of MLH1 and PMS2 (Jiang TJ et al. Cancer Commun (Lond), 2020 Nov;40:620-632). This amino acid position is poorly 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. -