Mutations in LRRK2 have been identified as the most common cause of dominantly inherited PD (Brice, 2005; Lesage et al., 2006; Ozelius et al., 2006; Healy et al., 2008) and importantly, variation in the LRRK2 gene has been implicated as a risk factor for sporadic PD (Kett and Dauer, 2012). Here, LRRK2 is linked to Parkinson disease.