Adult-onset ataxia: 3-methylglutaconyl-CoA hydratase deficiency, (103) 3-phosphoglycerate dehydrogenase deficiency (104), γ-glutamylcysteine synthetase deficiency, (105) OPA1 deficiency, (106) very long-chain fatty acid elongase 4 deficiency, (70) very long-chain fatty acid elongase 5 deficiency, (107) abetalipoproteinemia, (108) hereditary coproporphyria, (109) and complex MD (tremor, ataxia, myoclonus, perioral dyskinesias) cathepsin F deficiency, (110) (myoclonus, cerebellar ataxia, parkinsonism) Neuronal ceroid lipofuscinosis type 4 (Parry type) (23). The gene discussed is ELOVL4; the disease is Parkinson disease.