Electroretinographic Findings in Three Family Members with X-linked Juvenile Retinoschisis Associated with a Novel Pro192Thr Mutation of the XLRS1 Gene

Abstract

Purpose: To present ocular findings in three family members with X-linked juvenile retinoschisis (XLRS) associated with a novel Pro192Thr mutation. Cases: We examined 21- (Case 1), 17- (Case 2), and 10-year-old (Case 3) male patients who showed wheel-like cystic lesions in the macula and a silver-gray reflex in the peripheral retina. Case 2 was a cousin of Case 1. Case 3 was a brother of Case 2. Methods: Scotopic electroretinogram (ERG) (dim and bright flash), oscillatory potentials, photopic ERG, and 30-Hz flicker responses were recorded in each patient. The XLRS1 gene was analyzed in patient blood samples by a direct sequencing method. Results: A novel missense mutation (Pro192Thr) was identified in the XLRS1 gene in each patient. Variable b/a ratios upon scotopic bright flash stimulation were evident (Case 1: right 1.16, left 1.20; Case 2: right 0.98, left 1.01; Case 3: right 0.81, left 0.83). Only Case 3 showed the typical “negative” waveform. The amplitude of rod b-waves was significantly decreased in all patients. Conclusions: Three cases with a novel Pro192Thr mutation showed the phenotypic variation in ERG, especially in b/a ratio, which has been considered an important diagnostic parameter.