FREQUENCY OF COMMON AND NOVEL INACTIVATING APC MUTATIONS IN 202 FAMILIES WITH FAMILIAL ADENOMATOUS POLYPOSIS

In the course of presymptomatic diagnosis in families with familial ad enomatous polyposis (FAP) we screened 202 unrelated patients for mutat ions in the APC gene. Germ-line mutations were identified in 20.8% of the index patients by a single step screening procedure based on heter oduplex analysis of a PCR product encompassing codons 1027-1384 of the APC gene. The most common mutations in our sample were a 5 bp deletio n at codon 1309 in 9% of the families, a 5 bp deletion at codon 1061 i n 5% and a 4 bp deletion at codon 1068 in 2.5% of the families. In add ition, 11 novel mutations localized within the exons 11-15 of the APC gene were identified by the heteroduplex or SSCP methods.