DRD2 and Parkinson disease: As a member of the steroid-thyroid hormone-retinoid receptor superfamily, it controls the expression of many essential genes for the development of meso-diencephalic dopaminergic (mdDA) neurons, such as SLC6A3, SLC18A2, TH and DRD2. For all these genes, significant decreased expression values were observed, which are consistent with the upstream decrease in NR4A2. In addition, NR4A2 down-regulation is significantly associated with adult human brain aging and has been demonstrated to increase the expression of the known PD-associated gene alpha-synuclein65,66.