SNCA and Parkinson disease: Missense mutations and multiplications of SNCA (4q21) cause autosomal dominant PD (Chartier-Harlin et al. 2004; Ibanez et al. 2004; Kruger et al. 1998; Polymeropoulos et al. 1997; Singleton et al. 2003; Zarranz et al. 2004), whereas association studies showed that increased SNCA expression because of variation in the SNCA promoter region conferred risk for sporadic PD (Maraganore et al. 2006; Pals et al. 2004).