A test, requested by a specialist or consultant physician, to diagnose neuromyelitis optica spectrum disorder (NMOSD) or myelin oligodendrocyte glycoprotein antibody‑related demyelination (MARD), by the detection of one or more antibodies, for a patient: suspected of having NMOSD or MARD; and with any of the following: recurrent, bilateral or severe optic neuritis; recurrent longitudinal extensive transverse myelitis (LETM); area postrema syndrome (unexplained hiccups, nausea or vomiting); acute brainstem syndrome; symptomatic narcolepsy or acute diencephalic clinical syndrome with typical NMOSD magnetic resonance imaging lesions; symptomatic cerebral syndrome with typical NMOSD magnetic resonance imaging lesions; monophasic neuromyelitis optica (no recurrence, and simultaneous or closely related optic neuritis and LETM within 30 days of each other); acute disseminated encephalomyelitis; aseptic meningitis and encephalomyelitis; poor recovery from multiple sclerosis relapses Applicable not more than 4 times in 12 months