LRRK2 and Parkinson disease: The vast majority of PD patients are idiopathic, but a small number of patients show a familial inheritance where mutations in α-synuclein, Parkin, DJ-1, ubiquitin-C-hydrolase-L1 (UCHL1) or Leucine-rich repeat kinase 2 (LRRK2) play an important role [2], [3].