LRRK2 and Parkinson disease: A protein kinase implicated in familial and sporadic cases of PD is leucine‐rich repeat kinase 2 (LRRK2), wherein mutations in LRRK2 have been shown to increase kinase activity.154 LRRK2 and mutant LRRK2 localize to intracellular membranes in the rodent brain and human cells.