FAMILIAL VARIATION IN RETINAL PIGMENTATION IN ADENOMATOUS POLYPOSIS

Objective: To examine the relationship between familial adenomatous po lyposis and retinal pigment epithelial (RPE) pigmentation in affected patients and their first-degree relatives. Design: Retrospective study . Setting: Affected families across Canada registered in the Steve Ata nas Stavro Familial Gastrointestinal Cancer Registry, Subjects: A tota l of 134 subjects aged 10 to 35 years (at high risk for the disease) w ho had undergone examination of the gut by sigmoidoscopy, colonoscopy with biopsy or resection with biopsy and indirect ophthalmoscopy. Main outcome measures: Weighted eye score for large and small retinal lesi ons; family eye pigmentation index (FEPI), calculated from the weighte d eye scores for individual affected family members. Results: Families differed in the number and type of RPE lesions manifest, but affected family members showed similar pigmentation. An FEPI below 3 was uninf ormative, but with a medium or high FEPI the sensitivity and specifici ty of the index approached 100%. Conclusions: A positive retinal exami nation signifies a high risk for adenomatous polyposis, whereas a nega tive retinal examination is uninformative. Current molecular analysis is informative in 95% of families. However, in cases of spontaneous mu tation and in patients with no first-degree relatives available or wit h unknown parenthood, RPE lesions are the most valuable extracolonic m anifestation of adenomatous polyposis.