LRRK2 and Parkinson disease: The most common mutation associated with PD is c.6055G>A (p.Gly2019Ser) in leucine-rich repeat kinase 2 (LRRK2) (GenBank: NM_198578.4).2, 3, 4 LRRK2 is a multidomain protein involved in many cellular functions, including cell proliferation, survival regulation of neural stem cells (NSCs), and neurogenesis.5