Among the LRRK2 mutations, the particular G2019S variant represents the most commonly identified cause of late-onset PD, and has been shown to contribute uniquely to both familial and sporadic forms of the disease (Di Fonzo et al., 2005; Gilks et al., 2005; Kachergus et al., 2005; Lesage et al., 2005; Nichols et al., 2005; Ozelius et al., 2006; Trinh et al., 2006; Healy et al., 2008; Moore, 2008; Bouhouche et al., 2017). The gene discussed is LRRK2; the disease is Parkinson disease.