Spinocerebellar ataxia type 6 was first described in 1997 when researchers from the USA discovered that three different protein isoforms of the human α1A voltage-dependent calcium channel subunit (CACNA1A) contained a polymorphic CAG repeat expansion towards the C-terminal of the protein (Figure 3) [6,108,109]. The gene discussed is CACNA1A; the disease is spinocerebellar ataxia type 6.