Timely and accurate diagnosis of AQP4-IgG seropositive NMOSD and MOGAD in people with rheumatologic disease is crucial because treatment strategies may diverge when comparing NMOSD, MOGAD, and (co-occurring) rheumatologic disease.31, –, 33 Furthermore, given that previous studies have been confounded by lack of adequate evaluation for NMOSD and MOGAD, there is limited characterization of myelitis associated with rheumatologic disease occurring in the setting of dual MOG-IgG and AQP4-IgG seronegativity (“double-seronegative”). This evidence concerns the gene AQP4 and myelitis.