The Parkinson’s Progression Markers Initiative (PPMI) database was used to evaluate possible relations between variations in the genes of the 57 human P450s and their 3 redox partners, a cytochrome P450 reductase (POR), adrenodoxin (Adx) and adrenodoxin reductase (AdR), and the origin and development of PD. Here, POR is linked to Parkinson disease.