Further assessments should be considered to exclude hypovitaminosis, other metabolic disorders, infections, autoimmune encephalitis, and neoplastic and paraneoplastic disorders (e.g., anti-collapsin response mediator protein-5 [CRMP5/CV2] antibody-associated optic neuropathy and myelopathy or anti-Ma-associated diencephalic syndrome) (see Box 3 for details). The gene discussed is DPYSL5; the disease is Optic neuropathy.