Spinocerebellar ataxia type 40 (EFO_0009057) (SCA40) is a very rare subtype of autosomal dominant cerebellar ataxia type 1, characterized by the adult-onset of unsteady gait and dysarthria, followed by wide-based gait, gait ataxia, ocular dysmetria, intention tremor, scanning speech, hyperreflexia and dysdiadochokinesis. Also known as: SCA40, spinocerebellar ataxia 40.