Mutations associated with PD, in addition to the α-syn gene, commonly occur in genes encoding for proteins that are part of signal transduction cascades and mitochondrial quality control pathways such as the leucine-rich repeat kinase 2 (LRRK2), Parkin, PTEN induced kinase 1 (PINK1) and DJ-1 [9,12]. The gene discussed is LRRK2; the disease is Parkinson disease.