ATXN2 and spinocerebellar ataxia type 2: The pathogenic role of ATXN2 in human disease was first reported in familial spinocerebellar ataxia type 2 (SCA2) cases, in which the mutant allele of ATXN2 harboring highly expanded CAG/CAA repeats (> 34) was found [17, 18, 20].