CONGENITAL HYPERTROPHY OF THE RETINAL-PIGMENT EPITHELIUM ASSOCIATED WITH FAMILIAL ADENOMATOUS POLYPOSIS

Purpose: Multiple, bilateral areas of congenital hypertrophy of the re tinal pigment epithelium (CHRPE) have been described in association wi th familial adenomatous polyposis (FAP). Histopathologic findings have suggested a generalized effect of the FAP gene on the RPE, which coul d impair the functional integrity of the RPE. The clinical, psychophys ical, electrophysiologic, and fluorescein angiographic findings in CHR PE in subjects with FAP were assessed. Methods: RPE function was asses sed in 7 subjects with CHRPE and a family history of FAP. Four had doc umented FAP (mean age = 22.25 years) and the other three were siblings of affected subjects, with a 50% risk of developing FAP (mean age = 6 .33 years). All subjects underwent comprehensive ophthalmologic examin ation. Results: All subjects showed mild hyperopia (mean, + 1.13 D; be st corrected visual acuity, 20/20 or better). On perimetry, there were scotomas corresponding to some lesions, ERG showed normal rod, maxima l, single-flash cone, and flicker responses. Light-dark ratio was with in the normal range on EOG. Fluorescein angiography demonstrated norma l retinal vasculature overlying the CHRPE lesions, which blocked backg round choroidal fluorescence. A normal choriocapillaris was observed t hrough some hypopigmented lacuna. Conclusion: CHRPE has been related t o generalized expression of an abnormal gene in RPE, but its functiona l abnormalities tend to be localized.