MACULAR DYSTROPHY ASSOCIATED WITH MUTATIONS AT CODON-172 IN THE HUMANRETINAL DEGENERATION SLOW GENE

Background: Recently, mutations in the retinal degeneration slow (rds) gene which codes for peripherin-rds have been implicated as a cause o f autosomal dominant retinitis pigmentosa. Because this gene is expres sed in both rods and cones, mutations in the rds gene might be expecte d to cause degeneration affecting either the scotopic or photopic syst ems. Mutations at codon 172 of the rds gene have been identified in th ree families with autosomal dominantly inherited, progressive macular dystrophy. Methods: Affected individuals underwent ophthalmic examinat ion, scotopic perimetry, dark adaptometry, measurement of color-contra st sensitivity, and electroretinography to characterize the photorecep tor dysfunction. Results: In all but one affected member, symptoms of progressive central visual loss developed in the third or fourth decad e of life accompanied by central scotoma and well-demarcated atrophy o f the retinal pigment epithelium and choriocapillaris of the macula. I n general, cone and rod thresholds were elevated, and color-contrast s ensitivity was absent in the central visual field. Peripherally, the s cotopic sensitivities were normal, as was the recovery from bleach. Co ne electroretinograms were diminished in amplitude, and delayed in all affected adults except one. Rod electroretinograms were normal or nea r normal in amplitude, and had normal implicit times. Affected asympto matic children had macular changes, abnormal color-contrast sensitivit y, and reduced pattern and cone electroretinograms.