Because several studies have shown pSN FW to be a disease-progression biomarker in PD (Ofori et al., 2015, Burciu et al., 2017), the monoamine oxidase B (MAO-B) inhibitor rasagiline, which has several neuroprotective actions, was recently studied in a randomized controlled trial in PD to assess its effects on this outcome (Arpin et al., 2021). This evidence concerns the gene MAOB and Parkinson disease.