CYP46A1 and Parkinson disease: Interestingly, when combining metabolomics and epigenetics, the primary pathway of bile acid biosynthesis (including the reactions catalyzed by CYP46A1 and CYP39A1) has been shown to be perturbed in PD patients and a methylation locus was found in the promotor region of CYP39A1, possibly suppressing its expression (Vishweswaraiah et al., 2022).