CYP2B6 and Parkinson disease: Moreover, when considering the effect of SNPs in the genes of the P450 family to the manifestation of PD symptoms in patients with a genetic predisposition, it was shown that again cholesterol degradation was playing a critical role for the shift from people possessing a genetic predisposition but showing no symptoms of PD (GUN) to patients with the predisposition and showing symptoms (GPD patients) (Petkova-Kirova et al., 2023).