Retinitis pigmentosa-56 (RP56) is an early-onset form of RP with progressive visual-field loss and deterioration of visual acuity (Bandah-Rozenfeld et al., 2010). For a general phenotypic description and a discussion of genetic heterogeneity of retinitis pigmentosa, see 268000.

Bestrophinopathies, the spectrum of ophthalmic disorders caused by pathogenic variants in BEST1, are typically characterized by retinal degeneration. The four recognized phenotypes are the three autosomal dominant disorders: Best vitelliform macular dystrophy (BVMD), BEST1 adult-onset vitelliform macular dystrophy (AVMD), and autosomal dominant vitreoretinochoroidopathy (ADVIRC); and autosomal recessive bestrophinopathy (ARB). Onset is usually in the first decade (except AVMD in which onset is age 30 to 50 years). Slow visual deterioration is the usual course. Choroidal neovascularization can occur in rare cases. ADVIRC is also associated with panophthalmic involvement including nanophthalmos, microcornea, hyperopia, and narrow anterior chamber angle with angle closure glaucoma.

Microcornea, rod-cone dystrophy, cataract, and posterior staphyloma-1 (MRCS1) is characterized by poor visual acuity in early childhood. Congenital cataract and microcornea are followed by rod-cone dystrophy, with later development of posterior staphyloma (Cai et al., 2019). Genetic Heterogeneity of Microcornea, Rod-Cone Dystrophy, Cataract, and Posterior Staphyloma MRCS2 (see 193220) is caused by mutation in the BEST1 gene (607854) on chromosome 11q12; 1 such family has been reported.