Presymptomatic diagnosis of familial colon polyposis.

The gene responsible for familial adenomatous polyposis (FAP) has recently been mapped, identified and this makes the presymptomatic molecular diagnosis of the disease possible. It can be performed by direct mutation analysis or indirect haplotype analysis. In families where several affected individuals are available the indirect haplotype analysis is the easiest way for performing presymptomatic diagnosis of persons at risk. Among Hungarian families we have performed haplotype analysis using D5S346, a highly polymorphic dinucleotide CA repeat marker located 30-70 kb downstream from APC gene with the combination of restriction endonuclease Rsal site polymorphism. Marker regions were amplified by polymerase chain reaction (PCR) and basen on the above-mentioned polymorphic systems, the haplotype at the APC locus was determined. We believe that haplotype analysis of individuals at risk in large FAP families containing several affected members is a rapid, efficient, and highly valuable method for presymptomatic diagnosis of familial colon polyposis.