Thus far, at least eighteen genetic loci for familial PD have been found, and twelve familial PD candidate genes have been identified (ATP13A2, DJ-1, DNAJC6, EIF4G1, FBXO7, LRRK2, PARK2, PINK1, PLA2G6, SNCA, SYNJ1, and VPS35) (refs 9, 10). Here, LRRK2 is linked to Parkinson disease.