spinocerebellar ataxia type 1 (MONDO_0008119) (SCA1) is a subtype of type I autosomal dominant cerebellar ataxia (ADCA type I) characterized by dysarthria, writing difficulties, limb ataxia, and commonly nystagmus and saccadic abnormalities. Also known as: ATXN1 autosomal dominant cerebellar ataxia type I, SCA1, Sca1, autosomal dominant cerebellar ataxia type I caused by mutation in ATXN1.