Increased cell-free DNA concentrations in patients with obstructive sleep apnea

Blood concentrations of cell-free DNA, which is considered to be released during apoptosis, are elevated under some pathological conditions such as cardiovascular disease and cancer. The association between obstructive sleep apnea (OSA) and cell-free DNA concentrations has not been reported so far. The purpose of the present study was to examine the association between OSA and plasma DNA concentrations. A case-control study was conducted using a total of 164 men aged 39-67 years, who were free of coronary heart disease and cancer. Laboratory-based overnight polysomnography was performed for all participants. On the basis of polysomnography, patients with an apnea-hypopnea index (AHI) = 5-30 events/h were defined as having mild-moderate OSA (n = 33) and those with > 30 events/h were defined as having severe OSA (n = 49). All 82 controls had AHI < 5 events/h. Plasma DNA concentrations from all participants were analyzed for the beta-globin gene using fluorescence-based real-time polymerase chain reaction. Patients with severe OSA had significantly higher plasma DNA concentrations than persons with mild-moderate OSA and those without OSA (P < 0.05). AHI was significantly associated with body mass index (P < 0.001), hypertension (P < 0.001), and plasma DNA concentration (P < 0.05). After taking into account hypertension and other potential risk factors, persons with high plasma DNA concentrations (> 8 mu g/L) had approximately fourfold higher odds of OSA than those with low DNA levels. Further data are warranted to confirm the association for men and to evaluate the association for women.