Retinitis pigmentosa in South Africa.

Retinitis pigmentosa (RP), the commonest inherited form of blindness, is a heterogeneous condition which usually manifests as an isolated abnormality, but is occasionally a component of various rare syndromes. The basic defect in RP is unknown, but the recent molecular genetic discovery of linkage with a restriction fragment length polymorphism in X-linked RP offers the potential for carrier screening and antenatal diagnosis of this form of the disorder. In this article we present an overview of RP and an analysis of our findings from a questionnaire survey of 130 affected individuals in 63 families in the Cape Province and Natal. The proportions of the different genetic types of RP were generally in accordance with those found in overseas studies, being 14% autosomal dominant, 9,5% autosomal recessive and 6% X-linked recessive. A further 35% of the affected persons had RP together with other syndromic stigmata, while the remaining 35% could not be classified into any specific genetic category.