X-Linked Retinitis Pigmentosa: Current Status

Abstract

Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous group of retinal degenerative diseases, characterized by nightblindness, progressive restriction of the visual field and pigmentary retinopathy.1 At least 28 different genetic loci have been mapped for autosomal dominant, autosomal recessive, and X-linked forms of RP. [http://www.sph.uth.tmc.edu/Retnet/home.htm] The X-linked RP (XLRP) subtype is the most severe, with an early age of onset and more rapid progression, accounting for 10 to 20% of RP families.2,3 XLRP is also genetically heterogeneous with at least 5 mapped loci: RP2, RP3, RP6, RP23 and RP24, as schematically depicted in Figure 1. By linkage analysis, RP2 is predicted to account for 10–20% of XLRP and RP3 for 70–90%,4–6 depending on the population. Genes for these two major loci have now been cloned. Our laboratory has been involved in the mutational screening and functional analysis of the two identified XLRP genes (RPGR and RP2), as well as the positional cloning of two other XLRP loci (RP6 and RP24). This report summarizes these efforts as well as the current standing of XLRP research.