CACNA1A and autosomal dominant cerebellar ataxia: In addition, homozygotes in other SCA subtypes, such as SCA2, SCA6, and SCA17, also appeared early onset and atypical symptoms than heterozygotes (Hire, Katrak, Vaidya, Radhakrishnan, & Seshadri, 2011; Kato et al., 2000; Ragothaman et al., 2004; Soga et al., 2017; Takahashi et al., 2004; Toyoshima et al., 2004; Zühlke et al., 2003).