Phenotypic variability in RDH5 retinopathy (Fundus Albipunctatus)

Area of Science:

• Ophthalmology
• Genetics
• Retinal Diseases

Background:

• Fundus albipunctatus is an inherited retinal disorder.
• Mutations in the RDH5 gene are implicated in this condition.
• Phenotypic variability and novel mutations require further investigation.

Purpose of the Study:

• To characterize the phenotypic diversity in patients with RDH5 mutations.
• To identify and report novel genetic alterations in the RDH5 gene.
• To correlate genotype with clinical and functional findings in fundus albipunctatus.

Main Methods:

• Retrospective case series of nine patients from eight families.
• Comprehensive ophthalmologic examinations including fundus photography, autofluorescence, SD-OCT, and electroretinography.
• Genetic analysis of the RDH5 gene's coding regions and intron-exon boundaries.

Main Results:

• Eleven RDH5 mutations were identified, with nine being novel.
• Most patients exhibited normal visual acuity, except for one with central vision loss.
• Fundus examination revealed characteristic white dots, though one patient had normal fundi.
• Electrophysiology showed significant rod dysfunction, with electronegative ERGs suggesting cone involvement.
• Autofluorescence imaging indicated reduced signals, associated with white dots in younger individuals.

Conclusions:

• The clinical and electrophysiologic presentation of RDH5 retinopathy is highly variable.
• RDH5 mutations likely cause reduced autofluorescence due to absent retinoid fluorophores.
• Electronegative electroretinograms may reflect cone system function in the absence of normal rod function.