MOG is a glycoprotein localized on the surface of the myelin sheath as well as of the cell body and processes of oligodendrocytes ( 44, 45). In the past, MOG-Abs were particularly described in acute disseminated encephalomyelitis (ADEM), an inflammatory CNS disorder that, if it has an pediatric onset, is mostly monophasic and has a favorable outcome in the majority of cases ( 42, 43).

Recently, various publications described the detection of serum-Abs against myelin-oligodendrocyte-glycoprotein (MOG) in AQP4-Ab negative NMOSD patients including pediatric cohorts and few patients with MS ( 29вЂ“ 41). Whether AQP4-Ab positive and AQP4-Ab negative diseases are varieties of the same disorder or rather reflect different disease entities is a topic of ongoing research ( 26вЂ“ 28). In 20вЂ“30% of patients, depending on the assay used, AQP4-Abs are not detectable ( 24, 25). Women are disproportionately more often affected and, particularly in AQP4-seropositive patients, female to male-ratio can reach up to 10:1 ( 19, 22, 23). Disease onset ranges between 4 and 88 years with a mean age at onset of 39 years ( 18вЂ“ 21). Patients without long-term immunosuppressive therapy have a worse prognosis with a higher mortality rate ( 17). Thus, in relapsing NMOSD, which account for approximately 80вЂ“85% of cases, neurologic deficits frequently accumulate during the disease course. Despite treatment, recovery from attacks is often incomplete and disease remission rarely occurs ( 15, 16). Patients also frequently suffer from burdensome symptoms like pain, headache, depression, fatigue, and sleep disorders ( 10вЂ“ 14). In rarer cases, brainstem and brain involvement e.g., area postrema syndrome or diencephalic syndrome can occur ( 8, 9). In the majority of patients with NMOSD, autoantibodies (Abs) against the astrocyte aquaporin-4 (AQP4) water channel are detectable and patients typically suffer from recurrent attacks of severe optic neuritis or/and myelitis ( 3вЂ“ 7). The French term вЂњneuro-myГ©lite optique aiguГ«,вЂќ which may be translated as вЂњneuromyelitis optica acutaвЂќ was first used by Devic in 1894 ( 1, 2). Neuromyelitis optica spectrum disorders (NMOSD) are rare chronic inflammatory central nervous system diseases distinct from multiple sclerosis (MS). We discuss therapeutic options of acute attacks as well as longterm immunosuppressive treatment, including azathioprine, rituximab, and immunoglobulins. These include antibody and further laboratory testing, MR imaging and optical coherence tomography. Here we give an overview on current recommendations concerning diagnosis of NMOSD and MOG-EM. These clinical syndromes are now frequently referred to as вЂњMOG-encephalomyelitisвЂќ (MOG-EM). In some patients with symptoms of NMOSD, no AQP4-Abs but Abs against myelin-oligodendrocyte-glycoprotein (MOG) are detectable. Serum antibodies (Abs) against the aquaporin-4 water channel lead to recurrent attacks of optic neuritis, myelitis and/or brainstem syndromes. Neuromyelitis optica spectrum disorders (NMOSD) are autoantibody mediated chronic inflammatory diseases. 4Experimental and Clinical Research Center, Max Delbrueck Center for Molecular Medicine and CharitГ© вЂ“ UniversitГ¤tsmedizin Berlin, Berlin, Germany.3Department of Neuroradiology, CharitГ© вЂ“ UniversitГ¤tsmedizin Berlin, Corporate Member of Freie UniversitГ¤t Berlin, Humboldt-UniversitГ¤t zu Berlin, and Berlin Institute of Health, Berlin, Germany.2Department of Neurology, Graduate School of Medicine, Chiba University, Chiba, Japan.1NeuroCure Clinical Research Center, CharitГ© вЂ“ UniversitГ¤tsmedizin Berlin, Corporate Member of Freie UniversitГ¤t Berlin, Humboldt-UniversitГ¤t zu Berlin, and Berlin Institute of Health, Berlin, Germany.Nadja Borisow 1 *, Masahiro Mori 2, Satoshi Kuwabara 2, Michael Scheel 1,3 and Friedemann Paul 1,4

Define mog