Although relatively unknown due to the small number of patients with NMOSD, significant progress has been made in recent years in the study of NMOSD, such as the discovery of MOG-Ab, the NMOSDs diagnostic criteria developed by the International NMO Diagnostic Group (IPND) in 2015, and the development of new drugs, which deepened people’s understanding of NMOSDs. This evidence concerns the gene MOG and neuromyelitis optica.