After controlling for confounding variables, such as age, sex, body mass index (BMI), presence or absence of OSA, coronary heart disease, diabetes mellitus, hypertension, uric acid, creatinine, and C-reactive protein, the concentrations of OPG in the plasma were found to correlate only with age and with the occurrence of OSA. The gene discussed is CRP; the disease is obstructive sleep apnea syndrome.