In contrast, CYP7A1, described to be a cholesterol 7α-hydroxylase (Wu et al., 1999), is not significantly associated with PD, while CYP27A1 being a human sterol 27-hydroxylase (Ali et al., 2013) displays several SNPs with OR<0.2 indicating a more protective effect on the development of PD. Here, CYP7A1 is linked to Parkinson disease.