Genetic analysis of the APC gene in Taiwanese familial adenomatous polyposis.

Colorectal cancer has become the third leading cause of death from cancer in Taiwan. Familial adenomatous polyposis (FAP) is an autosomal dominant inherited disease characterized by the presence of multiple adenomatous polyps in the colon and rectum. The gene responsible for FAP (APC) was cloned in 1991. Extensive analyses of the mutation spectra in FAP kindreds have been performed in different countries, but the results have been highly variable (30-80%). In this study, we used denaturing high-performance liquid chromatography (DHPLC) followed by automatic sequencing in an effort to establish the mutation spectrum of APC from DNA of peripheral blood cells. Among the 6 FAP probands analyzed, mutations were detected in 3 (50%), 2 of which were novel. The first novel mutation was at codon 2166, with a C to T transition, resulting in a stop codon. The second novel mutation was at codon 1971, with a C to G transversion, resulting in an amino acid change from serine to cysteine. The third mutation involved an A insertion in the sequence of -AAAAAA- at codons 1554-1556, which created a downstream stop codon (codon 1558). This study is the first to report mutation analysis in Taiwanese FAP probands.