Frequency of congenital hypertrophy of the retinal pigment epithelium in familial adenomatous polyposis.

Congenital hypertrophy of the retinal pigment epithelium is a recognized clinical marker in familial adenomatous polyposis as an expression of the altered gene in this autosomal dominant disease. Ocular lesions could be discovered years before the development of intestinal polyposis. We studied 29 diagnosed patients, 38 relatives (first degree) of familial adenomatous polyposis kindreds and 26 controls (general population). Number, size and bilaterality of pigmented lesions were analysed in order to separate members affected and non affected by intestinal polyposis in familial adenomatous polyposis kindreds. Three of 26 families (23%) had patients with polyposis and normal fundus. Bilaterality and more than 4 lesions improved specificity or sensibility of the fundus examination. However, the best efficacy of the test was obtained with large lesions (sensibility 0.82 and specificity 0.97).