Different studies in patients with PD reported neurodegeneration of SN cells expressing DAT (McGeer et al., 1977; Kastner et al., 1993; Miller et al., 1999; Chu et al., 2006; Rudow et al., 2008; Kordower et al., 2013; Ishibashi et al., 2014) and the enzymatic machinery necessary for the degradation of DA (Lloyd & Hornykiewicz, 1970; Grote et al., 1974; Robinson et al., 1977; Saura et al., 1997). The gene discussed is SLC6A3; the disease is Parkinson disease.