Figure 2 Correlation between total IgG levels and anti-AQP4 IgG titer Correlation between total IgG levels and anti-AQP4 IgG titer Anti-AQP4 IgG levels were measured in 121 samples from 9 patients positive to AQP4 antibodies. Anti-AQP4 IgG titer decreases during the RTX follow-up period (panel A, Kruskal–Wallis test, p = 0.0001). One of 9 patients (#2) seroreverted during the follow-up period. A strong correlation between total IgG and anti-AQP4 IgG levels was shown in 7 of 9 patients (panel B; linear regression model, p < 0.0001). Andrea Marcinnò et al. Neurol Neuroimmunol Neuroinflamm 2018;5:e498 Copyright © 2018 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.