The serum MMP-9 levels were higher in the patients with severe OSA than in those with moderate OSA and the controls (78.8 ± 48.0 ng/mL vs. 51.3 ± 37.8 ng/mL, p = 0.011; 78.8 ± 48.0 ng/mL vs. 49.0 ± 18.6, p = 0.009, respectively; Fig. 1A). The gene discussed is MMP9; the disease is obstructive sleep apnea syndrome.