Risk factors for genetic typing and detection in retinitis pigmentosa.

An outpatient population with retinitis pigmentosa was evaluated with respect to best corrected visual acuity, cycloplegic refractive error, appearance of the lenses, presence or absence of bone spicule pigmentation, age of onset of night blindness by history, and presence or absence of a history of parental consanguinity. The population included 489 affected patients subdivided into the four following groups: 69 (14.1%) dominant, 67 (13.7%) autosomal recessive, 34 (7.0%) X-chromosome-linked, and 319 (65.2%) isolate. Contingency table and life table analyses showed that significant differences existed for these criteria among the various groups. An analysis based on data from 35 families showed significant differences with respect to best corrected visual acuity and cylindrical refractive error when comparing affected patients with their age-matched normal relatives. These findings support the idea that observations in a routine ocular examination can aid in genetic classification of affected patients and in selection of relatives of affected patients who are at higher risk for having early stages of retinitis pigmentosa.