CYP2D6 and Parkinson disease: After supporting the role of the xenobiotic-metabolizing P450s CYP2D6 and CYP2E1 for the development of PD and identifying new SNPs being over-represented in GDP and IPD patients, we decided to look at the other 14 xenobiotic-metabolizing P450s (Guengerich, 2017) to find out whether other ones play a prominent role in PD.