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- X linked retinitis pigmentosa
- RPGR gene (retinitis pigmentosa GTPase regulator)
- hearing loss
- ciliary abnormalities
Retinitis pigmentosa (RP) is a progressive retinal degeneration that affects about 1 in 4000 of the population.1 Approximately 15–30% of patients with RP have X linked retinitis pigmentosa (XLRP), which is the most severe form of RP consistently manifesting early in life.2,3 Night blindness is usually present in early childhood with loss of peripheral visual fields and ultimately central vision, resulting in registered blindness by the end of the third decade. Female carriers display a broad spectrum of fundus appearances ranging from normal to extensive retinal degeneration.4–6
XLRP is genetically heterogeneous with two major loci, RP2 (Xp11.23) and RP3 (Xp21.1). Both disease genes have now been identified (respectively RP27 and RPGR8–10) with RP2 mutations causing disease in approximately 15% of XLRP families,11,12 while RPGR mutations are reportedly more common, accounting for up to 75% of XLRP.10 Two other rare loci for XLRP have also been described on Xp22 and Xq26–27.13,141
Hong et al15 described the phenotype and pathology of an RPGR knockout mouse model. They showed the subcellular localisation of RPGR to the photoreceptor connecting cilia, and in the absence of RPGR partial mislocalisation of essential outer segment proteins. These data suggest a putative role for RPGR in the retina, controlling movement of essential proteins from the inner to the outer segment of photoreceptors via the connecting cilia. Several groups have recently identified a retina specific RPGR interacting protein (RPGRIP1).16–18 This protein also localises to the photoreceptor connecting cilium and is thought to be a structural component of the ciliary axoneme.18 Subsequent mutation screening in patients suffering from retinal diseases has identified mutations in RPGRIP1 as a cause of Leber congenital amaurosis.19,20
In this report, we present the phenotype of …
Footnotes
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The first two authors contributed equally to this work.