SNCA and Parkinson disease: Since 1997, 27 PD-associated genes have been identified with autosomal dominant (UCHL1, GBA, GIGYF2, DNAJC13, LRRK2, TMEM230, GCH1, EIF4G1, SNCA, HTRA2, RIC3, ATXN2, VPS35, CHCHD2), autosomal recessive (PRKN, PTRHD1, DJ1, PLA2G6, SPG11, FBXO7, DNAJC6, SYNJ1, ATP13A2, VPS13C, PODXL, PINK1) or an X-linked mode of transmission (RAB39B) [5].