In the past, the term Lynch syndrome has been used interchangeably with hereditary non-polyposis colorectal cancer (HNPCC); however, current practice favors the use of HNPCC to refer to a clinical diagnosis based on familial clustering and age of disease onset as defined by the Amsterdam or Bethesda criteria, while Lynch syndrome refers only to cases that fulfill those criteria and have identified mutations in DNA mismatch repair (MMR) genes [6, 7]. The gene discussed is MRC1; the disease is hereditary nonpolyposis colon cancer.