Table 4 demonstrates that if we consider patients having SNPs only in one P450 and in no other of the four P450, the biggest number of patients have PD-associated SNPs in CYP7B1 (70 out of 362; 19.3% of all IPD patients) and the lowest number of patients have SNPs only in CYP27A1 (4/362; 1.1%). This evidence concerns the gene CYP2B6 and Parkinson disease.