It has been 21 years since the IATM criteria were published, although newly discovered CNS demyelinating antibodies such as aquaporin-4 immunoglobulin G (AQP4-IgG), MOG-IgG, and GFAP-IgG] are now considered to be specific biomarkers for determining the etiology of myelitis, previously thought to be idiopathic. The gene discussed is AQP4; the disease is myelitis.