Univariate Cox proportional risk analysis indicated that high HN (p = 0.001), the mMRC dyspnea score (p = 0.037) and HRE (p = 0.001) were risk factors for COPD exacerbation, whereas high GDF15 or FGF21 levels were not. The gene discussed is FGF21; the disease is chronic obstructive pulmonary disease.