EDN1 and multiple system atrophy: Additionally, another study of genome-wide association study (GWAS) identified four potential risk variants on genes of microtubule-associated protein tau (MAPT), endothelin 1 (EDN1), f-box Protein 47 (FBXO47), and ELOVL fatty acid elongase 7 (ELOVL7) in MSA in European population [26], but no association was found in the Chinese population as presented in separate GWAS [41], suggesting that genetic risk factors for MSA maybe region- and ethnic-specific.