Where there is only a low positive serum MOG IgG, a positive result without a reported titre, or CSF restricted MOG IgG antibodies only, then at least one supportive clinical or radiological feature (bilateral simultaneous involvement, >50% length involvement, perineural optic sheath enhancement or optic disc oedema) and negative serum aquaporin-4 antibodies are additionally required to reduce the likelihood of misdiagnosis, and increase the specificity of conferring a diagnosis of MOGAD. The gene discussed is MOG; the disease is optic papillitis.