Although the etiology of PD still remains elusive, certain genes are known to influence PD susceptibility, for example, autosomal dominant PD is associated with SNCA[2], LRRK2[3], UCHL1[4] and VPS35[5,6], recessive parkinsonism with PRKN[7], PINK1[8] and DJ-1[9], and more complex forms of recessive parkinsonism with ATP13A2[10], PLA2G6[11] and FBXO7[12]. The gene discussed is LRRK2; the disease is Parkinson disease.