ADVANCES IN PEDIATRICS WITH DIAGNOSIS OF ADENOMATOUS POLYPOSIS-COLI BY GENETIC-STUDIES

Background. - The gene responsible for familial adenomatous polyposis, (APC), has been recently cloned and generic map with several polymorp hic markers has been established. Population and methods. - Blood samp les (20 ml) were taken from 34 subjects belonging to four families at risk for familial adenomatous polyposis. Nineteen of these 34, less th an 20 years old, had one parent having polyposis or dead because of it . Polyposis was diagnosed, in ten of these 19 by endoscopy. Genomic DN A was extracted from peripheral leukocytes and Southern blot analyses were performed in each family, using RFLPs on both sides of the APC lo cus. Results. - DNA analysis identified normal and mutant haplotypes a t the APC locus in each family. It was thus possible to follow the seg regation of mutant alleles. These results were compared with the anamn estic and endoscopic data. Bearing in mind the risk of recombination w hen using extragenic markers, RFLPs allowed early diagnosis of APC in pre and/or asymptomatic patients. Conclusions. - Genetic analysis can be used to diagnose APC in affected families, provided the risk of rec ombination is taken into account. Intragenic microsatellites markers w ill soon be available. These will provide more information on the APC gene, and hence direct molecular diagnosis of APC.