AQP4 and neuromyelitis optica: Nevertheless, several sub-analyses, and a recent study including 132 patients with NMO and anti-AQP4 Ab, showed that the DRB1*03:01 association depended on anti-AQP4 Ab positivity (p < 0.001, OR = 4.09, 95% CI [2.91–5.74]) [106, 109, 110, 114].