RP WITH OR WITHOUT PPRPE
RP WITH OR WITHOUT PRESERVED PARAARTERIOLE RETINAL PIGMENT EPITHELIUM
RETINITIS PIGMENTOSA WITH OR WITHOUT PARAARTERIOLAR PRESERVATION OF RETINAL PIGMENT EPITHELIUM
RP12
Heckenlively (1982) described 5 patients with retinitis pigmentosa of probable autosomal recessive inheritance who showed relative preservation of retinal pigment epithelium adjacent to and under retinal arterioles and hypermetropia (RP patients tend to be myopic). Affected sibs and ... Heckenlively (1982) described 5 patients with retinitis pigmentosa of probable autosomal recessive inheritance who showed relative preservation of retinal pigment epithelium adjacent to and under retinal arterioles and hypermetropia (RP patients tend to be myopic). Affected sibs and parental consanguinity were noted. Bleeker-Wagemakers et al. (1992) reported a consanguineous Dutch family of 90 members from a genetically isolated population in the north of the Netherlands. Affected members (approximately 40) presented with an early-onset form of retinitis pigmentosa, starting with night blindness before the age of 3 years. Nonrecordable electroretinograms (ERGs) and concentric visual field loss in the first decade were followed in most cases by macular involvement and decreased visual acuity before age 15. Visual acuity at age 30 was 0.2 or less. At funduscopy, pigmentary depositions and atrophy of retinal pigment epithelium (RPE) were seen. See also Humphries et al. (1992). Van den Born et al. (1994) observed clinical heterogeneity within this pedigree. Only some affected members displayed retinitis pigmentosa with characteristic preserved paraarteriolar RPE (PPRPE). Benayoun et al. (2009) studied a consanguineous family in which 4 of 9 offspring had severe, early-onset RP. All patients had nystagmus, and visual acuity, which was poor from early childhood, deteriorated to light perception only by the end of the second decade of life. Both scotopic and photopic ERGs were completely extinct in all affected individuals as early as 4 years of age. Funduscopic findings included typical bone spicule-type pigment deposits, attenuation of the retinal arterioles, and pale appearance of the optic disc.
Den Hollander et al. (1999) cloned a protein homologous to the protein 'crumbs' (CRB) of Drosophila melanogaster that they denoted CRB1 (crumbs homolog-1; 604210). In 10 unrelated RP12 patients, they identified a homozygous AluY insertion disrupting the open ... Den Hollander et al. (1999) cloned a protein homologous to the protein 'crumbs' (CRB) of Drosophila melanogaster that they denoted CRB1 (crumbs homolog-1; 604210). In 10 unrelated RP12 patients, they identified a homozygous AluY insertion disrupting the open reading frame (604210.0001), 5 homozygous missense mutations, and 4 compound heterozygous mutations in the CRB1 gene (see, e.g., 604210.0002-604210.0005). The similarity to CRB of Drosophila suggested a role for CRB1 in cell-cell interaction and possibly in the maintenance of cell polarity in the retina. The distinct RPE abnormalities observed in RP12 patients suggested that CRB1 mutations trigger a novel mechanism of photoreceptor degeneration. Den Hollander et al. (2001) identified CRB1 mutations (see, e.g., 604210.0006-604210.0009) in 5 of 9 patients who had RP with Coats-like exudative vasculopathy (see 300216), 1 of whom had PPRPE. Coats-like exudative vasculopathy is a relatively rare complication of RP that may progress to partial or total retinal detachment. Den Hollander et al. (2001) suggested that given that 4 of 5 patients had developed the complication in one eye and that not all sibs with RP had the complication, CRB1 mutations should be considered an important risk factor for the Coats-like reaction, although its development may require additional genetic or environmental factors. In affected members of a consanguineous family with early-onset retinitis pigmentosa, Benayoun et al. (2009) identified compound heterozygosity for a G1103R mutation (604210.0011) and a 10-bp deletion (604210.0012) in the CRB1 gene. Each mutation had previously been identified in homozygosity in a family diagnosed with Leber congenital amaurosis (LCA8; see 604210).