AQP4 and neuromyelitis optica: It has been reported that AQP4‐Ab was detectable in 84.6% patients with SLE and NMO or LETM/rON and in 62.5% patients with other CTD and NMO or LETM, which showed the coexisting relationship between other autoimmune diseases and AQP4‐Ab‐positive NMOSD patients (Jarius et al., 2011).