Phase 1 clinical trials of human GM-CSF (sargramostim, Leukine®) in PD patients demonstrated GM-CSF was safe and tolerated for up to 36 months, increased Treg frequencies and function, increased neuronal activity in cortical motor areas, and improved Unified PD Rating Scale part III (UPDRS III) scores [39], 80], 95]. The gene discussed is CSF2; the disease is Parkinson disease.