Prevalence of mental retardation in patients with hereditary retinoblastoma.

Dear Editor, We evaluated the cumulative incidence of mental retardation in patients with hereditary retinoblastomai. Records of the national Dutch retinoblastoma register were used. This register is complete from 1945 through 1994. Cooperation of the hereditary retinoblastoma patients or their parents was solicited by a letter from the ophthalmologist. The patients with hereditary retinoblastoma born between 1945 and 1970 were visited at home in 1985.1 On that occasion, information on mental retardation was collected. In addition, questionnaires were sent in 1993 to the patients' parents or caregivers to obtain up-to-date information regarding the patient's condition, visual acuity, and second primary tumors.