DNMT1 and Parkinson disease: In this regard, DNMT inhibitors exhibited conflicting results in pre-clinical models of PD; it has been indicated that 5-Aza-2′-Deoxycytidine (5-aza-dC), a DNMT inhibitor, can enhance the expression of TH—a gene implicated in the production of levodopa—but also the expression of SNCA and UCHL1, two genes contributing to PD pathogenesis [147].