In 2007, Tan et al. conducted a study exploring the role CYP1A2 rs762551 in PD, based on the following observations; (a) caffeine (and its main metabolite paraxanthine) appears to have a neuroprotective effect, and thus may protect against PD; and (b) rs762551 may affect the inducibility of CYP1A2, and thus influence the caffeine metabolism and its neuroprotective effect [33,44,55]. This evidence concerns the gene CYP1A2 and Parkinson disease.