AQP4 and erythema multiforme: Of interest, AQP4-IgG-positive NMO is characterized by a marked female predominance (male to female ratio ~1:10–12) [43]; in contrast, the male to female ratio was 1:2.2 in the pattern II patients and thus more similar to what has been reported in MS and in MOG-IgG-positive EM [35].