Objective: To identify phenotypic characteristics of a certain mutation in the peripherin/RDS gene.
Design: Case reports with clinical features and results of fluorescein angiography, electroretinography, kinetic visual field testing, dark adaptometry, and DNA analysis.
Setting: University medical center.
Patients: We studied the ocular findings in eight members of a Japanese family with autosomal dominant retinitis pigmentosa and cytosine-to-adenine transversion at the third nucleotide in codon 244 of the peripherin/RDS gene. This mutation resulted in a substitution of lysine for asparagine in amino acid 244 of peripherin/RDS, a photoreceptor-specific glycoprotein.
Results: Clinical findings of each affected member in this family showed a marked intrafamilial similarity, which may provide the natural course of the phenotype produced by the Asn244Lys mutation. Characteristic features include diffuse pigmentary retinal degeneration in the midperipheral and peripheral fundi associated with macular degeneration in the later stage, starting with bull's-eye maculopathy, and severely deteriorated electroretinographic findings in both rods and cones, even in the early stage.
Conclusion: The mutation at codon 244 of the peripherin/RDS gene causes both rod and cone degeneration, although the precise mechanism of retinal degeneration is currently unknown.