A joint research effort from Japan and the Mayo Clinic has identified an antibody that can help differentiate Devic syndrome-or neuromyelitis optica (NMO)-from multiple sclerosis (MS). NMO is generally considered to be a rare disease, but it may be underrecognized and is often misdiagnosed as MS, although it demands a treatment protocol that differs from that of MS. Indeed, in some countries, misdiagnosis may be as high as 30%, according to Mayo Clinic estimates. A research team hailing from the Department of Immunology and Neurology at the Mayo Clinic in Rochester, NY, led by neuroimmunologist Vanda A. Lennon, MD, PhD, in collaboration with a research team from Tohoku University School of Medicine in Japan, identified the autoantibody NMO-IgG, which appears to be a reliable marker for differentiating NMO from MS.