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Full-field ERG in patients with Batten/Spielmeyer-Vogt disease caused by mutations in the CLN3 gene

Purpose: To investigate, using full-field ERG, the retinal function in patients with Batten/Spielmeyer-Vogt disease caused by mutations in the CLN3 gene. Methods: Batten disease status of five patients was confirmed by the presence of vacuolated lymphocytes in peripheral blood and the identification of mutations in the Batten disease gene ( CLN3 ). Visual acuity, fundus appearance, and full-field ERG were examined in all patients (age 4-19 years). The examination was repeated in one patient after 16 months. Results: Three unrelated patients were homozygous for the most common mutation in CLN3, the 1.02 kb deletion; two patients (sisters) were heterozygous for the 1.02 kb deletion and an as yet unidentified mutation in the CLN3 gene. Full-field ERG recordings in all five patients demonstrated no rod responses and only small remaining cone responses, which could be detected with 30 Hz-flicker stimulation. Re-examination of a six-year-old girl after 16 months revealed a fast progression of the retinal degeneration. Conclusion: Full-field ERG recordings in Batten disease patients, both homozygous and heterozygous for the 1.02 kb deletion in the CLN3 gene, confirm retinal degeneration to be severe, widespread, and with a rapid progression early in the disease course. The onset of visual failure may be delayed when compared to the classic disease course, particularly in patients who are not homozygous for the most common CLN3 mutation, a 1.02 kb deletion. In that case, the disease progression in terms of other symptoms may also be further delayed.