Interaction between the angiotensin-converting enzyme gene insertion/deletion polymorphism and obstructive sleep apnoea as a mechanism for hypertension

Objective Obstructive sleep apnoea (OSA) confers a risk of hypertension and cardiovascular complications. Both the renin-angiotensin-aldosterone system and OSA are important determinants of blood pressure, but it is not fully known how they interact. The aim of this study was to explore the interaction between the angiotensin-converting enzyme ( ACE) gene insertion/deletion (I/D) polymorphism and OSA in the association with hypertension. Design A community-based, case-control design with hypertensive patients in primary care (n=157) and normotensive population controls (n=181). Methods All subjects underwent ambulatory polysomnography during one night. OSA was defined by a minimum of 10 apnoea/hypopnoea events per hour. Office blood pressure was measured and hypertension status was assessed. The genotypes were determined using polymerase chain reaction. Results An interaction analysis including sex, ACE I/D polymorphism ( DD and ID versus II), and OSA identified a significant interaction between OSA and the ACE I/D polymorphism: odds ratio ( OR) 6.3, 95% confidence interval (CI) 1.8-22.5, P=0.004 as well as between OSA and sex: OR 3.3, 95% CI 1.1-9.6, P=0.033. OSA was significantly associated with hypertension in men but not in women. Conclusion The interaction between the ACE gene I/D polymorphism and OSA appears to be an important mechanism in the development of hypertension, particularly in men.