Fatty acid hydroxylase-associated neurodegeneration (FAHN) (HSP/NBIA-FA2H) is characterized early in the disease course by central nervous system involvement including corticospinal tract involvement (spasticity), mixed movement disorder (ataxia/dystonia), and eye findings (optic atrophy, oculomotor abnormalities), and, later in the disease course, by progressive intellectual impairment and seizures. This evidence concerns the gene FA2H and Dystonia.