Pathogenesis of X-linked RP3: insights from animal models

Retinitis Pigmentosa (RP) is a genetically heterogeneous disorder characterized by rod and cone photoreceptor cell dysfunction. X-linked RP (XLRP) is one of the most severe forms of human retinal degeneration, as determined by age-of-set and progression, and accounts for six to 20 % of all RP cases. At least six XLRP loci have been identified, but RP3 is the major subtype of XLRP, accounting for 70 to 80 % of affected families. The RPGR gene is responsible for the RP3 form of XLRP and is mutated in 10-20 % of all RP patients. The pathogenesis of retinitis pigmentosa GTPase regulator (RPGR) mutant-causing RP is not clear, different animal models have been used to understand the pathogenesis of these diseases. In this brief review, we will summarize the functional characterization of RPGR and highlight recent studies in animal models, which will not only shed light on the disease mechanisms in XLRP but will also provide therapeutic strategies for RP treatment.