Pathogenic mutations in leucine-rich repeat kinase 2 (LRRK2) account for ~1% of all PD cases, of which LRRK2 G2019S is the most frequent; identified in ~30% of cases in some ethnicities (Ozelius et al., 2006; Hulihan et al., 2008). Here, LRRK2 is linked to Parkinson disease.