Hereditary nonpolyposis colorectal cancer (HNPCC) is a cancer‐predisposing condition
caused by inactivating mutations in at least four genes (MSH2, MLH1, MSH6, and PMS2)
belonging to the mismatch repair system. At present, availability of the microsatellite
instability (MSI) test allows screening of a relevant fraction of patients with a constellation of
features suggestive of HNPCC. By analogy with several other genetic disorders, it is clearly
emerging that the term HNPCC encompasses a wide spectrum of different clinical …

Hereditary nonpolyposis colorectal cancer (HNPCC), or Lynch syndrome, is the most
common form of hereditary colorectal cancer (CRC). A well‐orchestrated cancer family
history is essential for its diagnosis since, unlike its familial adenomatous polyposis (FAP)
hereditary cancer counterpart, HNPCC lacks distinguishing clinical stigmata of its cancer
genetic risk. Discoveries in the 1990s of germ‐line mutations, the most common of which are
hMSH2 and hMLH1, have added enormous power to the diagnosis of Lynch syndrome. Its …