PMS2 and cancer: While the major contributory genes for these syndromes have been identified and well-studied (BRCA1/BRCA2 for HBOC and MSH2/MSH6/MLH1/PMS2/EPCAM for LS), there remains a large percentage of associated cancer cases that are negative for germline mutations in these genes, including 80% of women with a personal or family history of breast cancer who are negative for BRCA1/2 mutations [1].