CYP2E1 and Parkinson disease: The first epigenome‐wide association study (EWAS) investigating DNA methylation landscapes in the putamen and cortex of PD and controls revealed three differentially methylated genes, including hypomethylation (>2.5‐fold) of cytochrome P450 2E1 gene (CYP2E1), which is predominantly expressed in neurons; a corresponding increase in its mRNA expression levels in both the putamen and cortex of PD patients was also reported, suggesting that altered methylation in cytochrome might cause an increase in susceptibility to PD [71].