Importantly, among the known genes associated with PD (SNCA, Parkinsonism Associated Deglycase (PARK)7, Leucine-rich repeat kinase 2 (LRRK2), PARK2, or PTEN-induced kinase 1 (PINK1), most of them require thorough investigations to establish a link between them and meth abuse, however, some relevant links cannot be ruled out. The gene discussed is SNCA; the disease is Parkinson disease.