Incidence and significance of congenital hypertrophy of the retinal pigment epithelium (CHRPE) in familial adenomatous polyposis coli (FAPC).

As part of a population based study of familial colorectal cancer 33 affected patients with familial adenomatous polyposis coli (FAPC) and 33 relatives, at 50% risk of inheriting FAPC, from 24 kindreds, were identified and examined. Fourteen of the affected patients had extracolonic manifestations of the FAPC gene. Twenty-five of the 33 affected patients had one or more areas of congenital hypertrophy of the retinal pigment epithelium (CHRPE) and 20 had more than three CHRPEs, all having bilateral lesions. There were significant interfamilial differences in the ocular findings. Because of this interfamilial difference in the predisposition to develop CHRPEs it is important to establish the CHRPE status of individual FAPC families before the results of ophthalmoscopy can be used to predict the carrier status of at risk relatives.