Several dominant-inherited single point mutations in SNCA gene have been identified in families that develop early onset PD (Polymeropoulos, 1997; Krüger et al., 1998; Zarranz et al., 2004; Appel-Cresswell et al., 2013; Lesage et al., 2013; Pasanen et al., 2014). The gene discussed is SNCA; the disease is Parkinson disease.