Molecular analysis of the APC and MYH genes in Czech families affected by FAP or multiple adenomas: 13 novel mutations.

Familial adenomatous polyposis (FAP) is an autosomal dominant predisposition to colorectal cancer and is caused by germline mutations in the adenomatous polyposis coli gene. The most prominent clinical manifestation is the presence of hundreds to thousands of colorectal polyps. A milder phenotype is found in patients affected with AFAP/ multiple adenomas. We screened the entire APC coding region using the combination of DGGE, PTT and direct sequencing and identified causative mutations in 52 of 77 patients. Thirteen of the mutations found were novel. In addition, we also tested 21 APC mutation/negative probands for the two most common mutations in the MYH gene. Four patients showed neither dominant transmission of the disease nor evidence of APC mutations. In one of them the most common biallelic germline mutation in the MYH gene was detected. Correlations between the localization of germline mutations and clinical manifestations of the diseases are discussed.