Patients with germline DNA MMR mutations in MLH1, MSH2, MSH6 and PMS2 or mutations in EPCAM (leading to impaired DNA repair through epigenetic silencing of MSH2) are defined as having LS 9, 10, 11, whereas the mutation negative patients are referred to as belonging to the entity known as HNPCC and only have a clinical diagnosis of the disease according to the Amsterdam criteria. The gene discussed is MLH1; the disease is hereditary nonpolyposis colon cancer.