LRRK2 and Parkinson disease: The informative nature of PD causing mutations on the molecular basis of disease is demonstrated by LRRK2, because clinical phenotypes of PD caused by LRRK2 mutation are largely indistinguishable from idiopathic disease (Ishihara et al., 2006; Ross et al., 2006; Haugarvoll et al., 2008; Haugarvoll and Wszolek, 2009), however ascertainment of larger LRRK2 Gly2019Ser patient populations will certainly define distinct clinical and pathologic features of LRRK2 parkinsonism (Zimprich et al., 2004; Adams et al., 2005; Whaley et al., 2006; Sossi et al., 2010).