CYP2E1 and alcoholic fatty liver disease: There was significant up-regulation of the genes that encode the cytochrome P450 family 2 subfamily E polypeptide 1 (CYP2E1) and alcohol dehydrogenase 4 (ADH4) enzymes, which play important roles in the production of reactive oxygen species (ROS) in alcoholic fatty liver disease and NAFLD patients38, 39.