Besides its role in central nervous system (CNS), NURR1 is an active player and a potential peripheral biomarker of PD, since downregulated gene expression levels were found in peripheral blood mononuclear cells (Le et al., 2008; Liu et al., 2012) and whole blood (Montarolo et al., 2016) of PD patients. Here, NR4A2 is linked to Parkinson disease.