Hereditary non-polyposis colorectal cancer (HNPCC) or Lynch syndrome is an autosomal dominant disease primarily associated with germline mutations in DNA mismatch repair genes. HNPCC accounts for 2-3% of all colorectal cancer. Approximately 1.5% of colorectal cancers are associated with defects in the PMS2 gene even though the penetrance for monoallelic mutation carriers is lower than other mismatch repair genes2. PMS2 associated tumors can also be found in tumors from other organs. There is evidence to suggest that MSH6 and PMS2 alone are sufficient to determine mismatch repair deficiency4. Presence of a BRAF V600E mutation is likely to suggest PMS2 negativity due to somatic hypermethylation.