ATXN2 and spinocerebellar ataxia type 2: Spinocerebellar ataxia type 2 (SCA2) is an autosomal-dominantly inherited neurodegenerative disorder, caused by repeat expansion mutations in the ataxin-2 (ATXN2) poly-glutamine domain (polyQ, encoded by CAG repeats at the DNA level) [1,2,3].