HAP1 has been reported to associate with TATA binding protein (TBP) and ataxin-3, which are the causative agents of polyQ-expansion-dependent neuropathology of SCA17 and SCA3, respectively (Prigge and Schmidt, 2007; Takeshita et al., 2011). The gene discussed is ATXN3; the disease is spinocerebellar ataxia type 17.