In particular, previous studies have reported differential DNA methylation at PD-related genes (MAPT, CYP2E1, and STX1B)13–15, and hypomethylation of the α-syn gene (SNCA) is associated with decreased protein levels in the substantia nigra (SN) and striatum of postmortem PD brain16–23. The gene discussed is CYP2E1; the disease is Parkinson disease.