LRRK2 and Parkinson disease: Because the phenotype of LRRK2 mutation carriers seems to be indistinguishable from that of individuals with idiopathic PD (Marras et al., 2011), it has been hypothesized that targeting the increased LRRK2 kinase activity caused by these mutations might not only be therapeutic to those carrying the mutation but also to those who have the idiopathic form of the disease.