Clinical features of Japanese pediatric patients with anti-aquaporin 4 antibody

Recently, a disease-specific antibody was found in serum from patients with neuromyelitis optica (NMO), and its target antigen was identified as aquaporin 4 (AQP4) water channel protein. There is no clinical picture of pediatric cases with anti-AQP4 antibody, except one report from North America. Here, we report the clinical features of 18 Japanese anti-AQP4-antibody-positive patients with childhood-onset of NMO. Of the 2,000 patients who had been examined for anti-AQP4 antibody at Tohoku University Hospital up until 2008, 60 were under 15 years of age at onset, and 18 of them were positive for anti-AQP4 antibody. We analyzed the clinical information on those patients. There were 14 girls and 4 boys (M : Fratio=1 : 3.5). The age of onset ranged from 3 to 15 years old (median 13). The clinical diagnoses of the 18 patients before the anti-AQP4 antibody tests were : NMO in 8 (44%), MS in 7 (39%), and opticospinal MS (OSMS) in 3 (17%). Nine patients developed only optic neuritis at onset. At the last follow-up, brain magnetic resonance imaging (MRI) was abnormal in 14 patients, nine had monocular or binocular blindness, and the expanded disability status scale score was 6.0 or higher (cannot walk without support) in eight patients. NMO has a poor prognosis, as seen in adult cases, suggesting the importance of an early diagnosis using the anti-AQP4 antibody test to institute effective immunosuppressive treatment.