The remaining fifteen key candidate genes (IER2, BTG2, PPP1R15A, EIF1, SGK1, DUSP1, SOCS3, CXCL8, LTF, DEFA1B, DEFA1, DEFA3, HBB, HNA1 and HBA2) have not been found to be significantly associated with PD and exercise. The gene discussed is CXCL8; the disease is Parkinson disease.