ATXN2 and spinocerebellar ataxia type 2: Spinocerebellar ataxia type 2 (SCA2) is a rare and fatal dominantly-inherited polyglutamine (polyQ) disease [1, 2], being caused by abnormal repeats of the triplet CAG in the ATXN2 gene, resulting in an expanded polyQ chain in the ataxin-2 protein [3, 4].