While the dominantly inherited familial mutations are restricted to α-syn and leucine rich repeat kinase 2 (LRRK2) genes (Sundal et al., 2012), studies suggest that LRRK2 mutations are the most common genetic contributor to PD (Zimprich et al., 2004; Paisan-Ruiz et al., 2004). Here, LRRK2 is linked to Parkinson disease.