ATXN1 and spinocerebellar ataxia type 1: Spinocerebellar ataxia type 1 (SCA1), an autosomal dominant neurodegenerative disease, is one of the neurodegenerative diseases caused by expansion of a CAG trinucleotide tract that encodes a polyglutamine stretch in the resulting ataxin-1 (ATXN1) protein (1, 2).