Contributor: Gordon K. Klintworth
Several types of retinitis pigmentosa have an autosomal dominant mode of inheritance. Autosomal dominant retinitis pigmentosa acounts for 3-39% of cases of retinitis pigmentosa depending on the country; 9% Switzerland, 39% United Kingdom) and the genes responsible for some types of autosomal dominant retinitis pigmentosa have been identified. They include IMPDH1, MTTS2, NRL, ORP1, PRKCG, and RHO. The types of autosomal dominant retinitis pigmentosa include retinitis pigmentosa type 1, retinitis pigmentosa type 4, retinitis pigmentosa type 8, retinitis pigmentosa type 9, retinitis pigmentosa type 10, retinitis pigmentosa type 11, retinitis pigmentosa type 13, retinitis pigmentosa type 17, and retinitis pigmentosa type 27. Rods and cones degenerate in these non-inflammatory inherited retinal degenerations. Initial symptoms include nyctalopia during adolescence. A ring scotoma develops and extends peripherally until only a small visual field remains (tunnel vision, visual field constriction), which too is eventually lost. Fundoscopic exam reveals extremely attenuated retinal blood vessels. Eventually the ERG shows no activity. The optic disc develops a waxy yellowish pallor due to glial proliferation. The retinal pigment epithelium atrophies and becomes mottled gray with hyperpigmented and hypopigmented areas. The pigment has an appearance of bone corpuscles. The choriocapillaris eventually atrophies, exposing large vessels and a whitish yellow choroid.