Objective: To assess the clinical and genetic characteristics of a Japanese family with fundus albipunctatus with progressive cone dystrophy associated with a mutation in the RDH5 gene.
Design: Case report with clinical findings and results of fluorescein angiography, electroretinograms, kinetic visual field testing, dark adaptometry, and DNA analysis.
Setting: University medical center.
Patients: We studied the ocular findings in 6 members of a Japanese family with fundus albipunctatus with cone dystrophy and a guanine-to-adenine transversion at the first nucleotide in codon 35 of the RDH5 gene. The mutation resulted in a substitution of serine for glycine in amino acid 35 (Gly35Ser) of the RDH5 gene.
Results: Characteristic features included poor night vision, white dots in the retina, cone dystrophy, and a mottled appearance of the retinal pigment epithelium. Electroretinograms showed greater impairment of the rod-mediated responses than the cone-mediated responses. After 3 hours of dark adaptation, the a and b waves and scotopic b waves recovered.
Conclusions: Although the mutation of the RDH5 gene has been known as a causative gene of fundus albipunctatus, the Gly35Ser mutation in the RDH5 gene may be related to the pathogenesis of progressive retinal degeneration. This phenomenon may provide evidence of gene phenotype caused by a mutation in the RDH5 gene.
Clinical relevance: The Gly35Ser mutation causes fundus albipunctatus with cone dystrophy. This finding provides evidence that some kinds of mutations in the RDH5 gene are related, in part at least, to the pathogenesis of progressive retinal degeneration.