Although most cases with PD are sporadic, more than 20 responsible genes in familial cases were identified since 1997, including autosomal dominant and recessive genes, such as snca, lrrk2, vps35, pink1, parkin, dj-1, dnajc6, fbxo7, synj1, atp13a2, and pla2g6 (7, 17, 18). The gene discussed is SNCA; the disease is Parkinson disease.