Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2PM4_SupportingPP3
The NM_000535.7(PMS2):c.736_741delCCCCCTinsGTTGTGAAG(p.Pro246_Pro247delinsValValLys) variant causes a missense, conservative inframe insertion change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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]
Uncertain significance, criteria provided, single submitter
clinical testing
Ambry Genetics
Jun 23, 2016
The c.736_741delCCCCCTinsGTTGTGAAG variant, located in coding exon 7 of the PMS2 gene, results from an in-frame deletion of CCCCCT and insertion of GTTGTGAAG between nucleotide positions 736 and 741. This results in the removal of two proline residues and insertion of three residues, two valine and one lysine. This variant was not reported in population based cohorts in the following databases: Database of Single Nucleotide Polymorphisms (dbSNP), NHLBI Exome Sequencing Project (ESP), and 1000 Genomes Project. In the ESP, this variant was not observed in 6503 samples (13006 alleles) with coverage at this position. To date, this alteration has been detected with an allele frequency of approximately 0.001% (greater than 150000 alleles tested) in our clinical cohort. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -