Assessment of clinical variables and counseling needs in patients with retinitis pigmentosa.

Many medical and personal factors must be considered when attempting to provide comprehensive genetic counseling to families with retinitis pigmentosa (RP). Adequate diagnostic evaluation, the initial step in the counseling process, is not always readily obtained. Prognosis is difficult to assess, and genetic type may be impossible to establish in certain pedigrees. A nationwide questionnaire survey of 899 probands with RP and allied disorders was conducted, and generated data on the patient's perceptions of the clinical aspects of the disease, family history, and the understanding of the disorder by affected persons and their relatives. This study emphasizes the clinical variability of RP and summarizes differences in age of onset of the different genetic types. Clearly, patients must be evaluated extensively and carefully to diagnose retinitis pigmentosa accurately. The extent and limitations of the diagnostic evaluation should be clearly understood by the counselor because some patients with sporadic phenocopies may be diagnosed as having retinitis pigmentosa. Counseling about prognosis should include information regarding the great variation among and within inheritance groups, families, and individuals with respect to age of onset and natural history of the disorder. All patients should be considered for hearing evaluations since as many as 30% of RP patients may have hearing impairments. Because no treatment is currently available for most RP patients, genetic counseling and supportive follow-up should be viewed as an essential service for this common group of genetic disorders, and co-operation with the ophthalmologic diagnostician should be actively sought.