Yet others may have the same autoimmune-related NMO but maybe seronegative for AQP-4 antibody, as the test has a variable sensitivity of 70% – 80%.21,22 Some of the patients may have the uncommon anti-myelin oligodendrocyte glycoprotein (MOG)-mediated disease which presents in a similar manner. The gene discussed is AQP4; the disease is neuromyelitis optica.