Significant associations between the MMP-9 -1562C/T polymorphism and risk of OSA were also observed under heterozygote comparison (CT vs. CC: OR = 1.86, 95% CI = 1.15–3.01) and dominant genetic model (CT/TT vs. CC: OR = 1.78, 95% CI = 1.11–2.85). This evidence concerns the gene MMP9 and obstructive sleep apnea syndrome.