The Friedreich's ataxia mutation was found in five patients (4%), the spinocerebellar ataxia (SCA) 2 mutation in one (1%), the SCA3 mutation in two (2%) and the SCA6 mutation in seven (6%).
Voltage-dependent calcium channel mutations have been associated with spinocerebellar ataxia in humans (SCA6) and with ataxia, progressive cerebellar degeneration, and epilepsy in mice (tottering, lethargic, and stargazer).
Spinocerebellar ataxia 6 (SCA6) is an autosomal dominant spinocerebellar degeneration caused by the expansion of the polymorphic CAG repeat in the human alpha1A voltage-dependent calcium channel subunit gene (CACNL1A4 gene).