The MDSCs was detected to be significantly increased in peripheral blood of patients with PD compared with healthy control individuals, which led to the increased production of immunosuppression-related genes [arginase 1 (ARG1), interleukin-10 (IL-10), and cyclooxygenase 2 (COX-2)] (Yang et al., 2018). This evidence concerns the gene ARG1 and Parkinson disease.