ATXN1 and spinocerebellar ataxia type 1: In spinocerebellar ataxia 1 (SCA1) patients, the mutant ATXN1 gene contains CAG repeats that encode an expanded polyglutamine (polyQ) region, and the formation of distinct nuclear “inclusions” of these polyQ-ataxin-1 proteins in SCA1 patients and transgenic mice23–25.