Abnormally aggregated α-Syn and tau are often found together in postmortem cases of PD and LBD (Arima et al., 1999; Colom-Cadena et al., 2013; Iseki et al., 2002; Ishizawa et al., 2003), and genetic interaction studies in Drosophila demonstrate that α-Syn and tau synergize in promoting toxicity (Roy and Jackson, 2014). The gene discussed is MAPT; the disease is Parkinson disease.