Mutations in the gene BEST1 cause five clinically recognized retinal degenerative eye diseases in man: Best vitelliform macular dystrophy (BVMD)1,2, adult onset vitelliform macular dystrophy (AVMD)3, autosomal recessive bestrophinopathy (ARB)4, autosomal dominant vitreoretinochoroidopathy (ADVIRC)5, and retinitis pigmentosa 50 (RP50)6,7. The gene discussed is BEST1; the disease is retinitis pigmentosa 50.