LRRK2 and Parkinson disease: Since the age-associated penetrance of G2019S LRRK2 in idiopathic PD has been reported in previous studies (Marder et al. 2015; Lee et al. 2017), we hypothesized that the presence of the G2019S LRRK2 mutation in dopaminergic neurons could harbor a comparable condition of idiopathic PD and its release of α-syn.