Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2PM5PP3_Strong
The NM_000535.7(PMS2):c.353G>T(p.Ser118Ile) variant causes a missense, splice region 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. 3/3 splice prediction tools predicting alterations to 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. S118N) has been classified as Likely pathogenic.
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]
Verdict is Likely_pathogenic. Variant got 8 ACMG points.
PM2
Very rare variant in population databases, with high coverage;
PM5
Other missense variant is known to change same aminoacid residue: Variant chr7-6003690-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 525724.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
PP3
Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
Uncertain significance, criteria provided, single submitter
clinical testing
University of Washington Department of Laboratory Medicine, University of Washington
May 01, 2018
PMS2 NM_000535.5:c.353G>T has a 86.7% probability of pathogenicity based on combining prior probability from public data with a likelihood ratio of 0.20 to 1, generated from evidence of seeing this as a somatic mutation in a tumor without loss of heterozygosity at the PMS2 locus. See Shirts et al 2018, PMID 29887214. -