For instance, mutations in leucine-rich repeat kinase 2 (LRRK2), the most frequent causative gene identified in PD (Zimprich et al., 2004; Trinh et al., 2014), result in dysfunction of astrocytes in the clearance of α-synuclein, thereby decreasing the number of DA neurons (Greggio et al., 2006). The gene discussed is LRRK2; the disease is Parkinson disease.