DIAGNOSTIC-VALUE OF FUNDUS EXAMINATION IN FAMILIAL ADENOMATOUS POLYPOSIS

Background-Multiple, bilateral lesions of congenital hypertrophy of th e retinal pigment epithelium (CHRPE) have been described in patients s uffering from familial adenomatous polyposis (FAP) since 1980. This st udy aimed to determine a reliable diagnostic criterion, based on the s ize and number of retinal CHRPE lesions, allowing the screening of pat ient carriers of the gene responsible for FAP. Methods-32 control subj ects and 144 patients belonging to 85 FAP families were studied, divid ed into 124 carriers of the genetic alteration and 20 non-carriers. Re sults-In carriers of the deleted gene, multiple, bilateral retinal les ions were consistently observed. Lesion situation, size, shape, and de gree of pigmentation were variable however. A positive criterion for F AP was defined as the presence of at least four lesions whatever their size, or at least two lesions one of which is large. This criterion s howed a high sensitivity (0.68) and a maximal specificity (1). Within each family, the retinal phenotypic expression was homogeneous. CHRPE lesions were observed in two thirds of the FAP families and absent fro m the remaining-third. Conclusion-By using this new positive diagnosti c criterion, fundus examination allows early detection of those childr en carrying the gene responsible for FAP in families positive at ocula r examination.