Assessing the risk of retinitis pigmentosa with age-of-onset data.

Early characteristic electrophysiologic and ophthalmoscopic changes may help predict the development of retinitis pigmentosa. Until recently, if these were absent or equivocal, the ophthalmologist had to rely on the family pattern of transmission and simple Mendelian genetic methods to calculate the patient's risk of manifesting the disease. We used data on age of onset of subjective night blindness in 229 patients with retinitis pigmentosa (189 with autosomal recessive disease, 27 with autosomal dominant disease, and 13 with X-chromosome-linked disease) with Bayesian methods of probability calculation to predict the risk of retinitis pigmentosa development in a given patient more accurately than is possible with simple Mendelian methods. The risk for one subject used as an example was reduced from 50% to 12.9%.