ERG variability in X-linked congenital retinoschisis patients with mutations in the RS1 gene and the diagnostic importance of fundus autofluorescence and OCT

Purpose X-linked congenital retinoschisis (RS) is a relatively frequent retinal dystrophy associated with RS1 gene mutations. A negative electroretinogram (ERG), i.e., a b/a wave ratio 1.0. Another patient had a b/a wave ratio of 0.96 in one eye and 1.02 in the fellow eye. In 10 of 23 patients, the b/a wave ratio ranged from 1.03 to 1.34. Single-flash cone and 30 Hz flicker responses were always reduced. FAF and OCT were pathologic in all patients tested. FAF was increased in the fovea. OCT revealed foveal schisis to various degrees and thinning of the retina in an older patient. Conclusions Although ERG abnormalities were detected in all patients tested, more than 40% of patients with RS1 mutations did not have a negative ERG. In clinically suspected RS a combination of ERG, FAF, OCT, and molecular-genetic testing is advised to verify the diagnosis