Several studies have found that gene polymorphisms in xenobiotic pathways, such as cytochrome P450 family 2 subfamily E member 1 (CYP2E1), glutathione S-transferase Mu 1 (GSTM1), NAD(P)H: quinone oxidoreductase (NQO1), N-acetyltransferase 2 (NAT2), and multidrug resistance protein 1 (MDR1), influence leukemia risk alone or in combination with chemical exposure [166]. This evidence concerns the gene CYP2E1 and leukemia.