[Familial and genetic study in a large Chinese kindred with hereditary nonpolyposis colorectal cancer].

Objective: Hereditary nonpolyposis colorectal cancer (HNPCC) is one of the most common hereditary colon cancer syndromes accounting for 1%-5% of all colorectal cancer cases. Germline mutations in at least five genes coding for DNA mismatch repair (MMR) proteins are associated with the clinical phenotype of HNPCC. More than 400 MMR mutations have been identified in HNPCC patients, and about 40% of mutations affect MSH2 gene including nucleotide substitutions, deletions, and insertions.