LRRK2 and Parkinson disease: Parkinson's disease (PD) is the second most common neurodegenerative disease, affecting about 2% of people over 65,1 and several genes have been identified to cause familial PD, including SNCA (encoding α‐synuclein), PINK1 (encoding PTEN‐induced putative kinase 1, PINK1), PRKN (encoding Parkin), and LRRK2 (encoding leucine‐rich repeat kinase 2, LRRK2).2, 3