A central pathological hallmark of MJD is the aggregation propensity of polyQ-expanded ataxin-3, which accumulates in the nucleus and axons of neuronal cells as inclusion bodies, ultimately leading to their degeneration (Paulson et al., 1997; Schmidt et al., 1998; Seidel et al., 2010). The gene discussed is ATXN3; the disease is Spinocerebellar ataxia type 3.