Ataxin 1 (ATXN1)

The protein ataxin-1 is encoded by the ATXN1 gene, which is mutated to contain an expanded CAG trinucleotide repeat in spinocerebellar ataxia-1 (SCA1), an autosomal dominant form of olivopontocerebellar atrophy. Although there are forms of spinocerebellar ataxia that are indistinguishable clinically from SCA1, e.g., SCA2, the designation SCA1 is used for the form that maps to 6p. Banfi et al. (1994) demonstrated that the ATXN1 gene encodes an 816-amino acid protein with a molecular mass of 87 kD. The (CAG)n repeat, coding for a polyglutamine tract, lies within the coding region, and the protein is transcribed from both the wildtype and the CAG-expanded ATXN1 allele.