<p>The Post-Meiotic Segregation 2 (PMS2) protein is a component of the MMR (Mis-Match Repair) complex involved in DNA repair. In <taxon tax_id="9606">Homo sapiens</taxon> (Human), PMS2 forms an alpha heterodimer with the MLH1 protein. The gene was originally identified as having a low chromosome segregation defect in meiosis in <taxon tax_id="4932">Saccharomyces cerevisiae</taxon> (Baker's yeast) [<cite idref="PUB00035063"/>], in which organism MLH1/PMS2 is a single gene. Germline mutations in the PMS2 gene have been shown to give rise to Turcot syndrome, which is the co-occurrence of a primary brain tumour and multiple colorectal adenomas [<cite idref="PUB00035064"/>]. It has also been shown that in families having a history of hereditary nonpolyposis colorectal cancer (HNPCC), PMS2 was seen to have large internal deletions in the gene [<cite idref="PUB00035065"/>]. It was later shown that HNPCC patients having germline mutations either in PMS2 or MHL1 had a much higher rate of chromosomal mutations compared to control individuals [<cite idref="PUB00035066"/>].</p>