Angiotensin converting enzyme in patients with sleep apnoea syndrome: plasma activity and gene polymorphisms

The prevalence of several cardiovascular diseases is increased with obstruc tive sleep apnoea syndrome (OSAS), due to, as yet, unclear reasons. Angiote nsin converting enzyme (ACE) abnormalities have been implicated in the path ogenesis of various cardiovascular diseases. In this study, plasma ACE acti vity and the distribution of an insertion (I)/deletion (D) polymorphism of the ACE gene were determined in OSAS patients and in healthy controls. A total of 63 patients with OSAS (mean+/-SEM 54.5+/-2.5 apnoea/hypopnoeas.h (-1)) and 32 healthy subjects were studied. To avoid potential confounding factors, patients treated with ACE inhibitors or continuous positive airway pressure were excluded, as well as controls in whom a blood sample was not obtained earl in the morning. ACE activity was determined spectrophotometr ically in 46 OSAS patients and 25 controls. The I/D ACE polymorphism was de termined by polymerase chain reaction in 44 patients and 32 controls. ACE activity was higher in OSAS patients (53.9+/-2.5 IU.L-1) than in health y controls (42.4+/-3.1 IU.L-1, p<0.01). This was independent of the presenc e of arterial hypertension. The frequency distribution of the DD, II and ID genotypes in OSAS patients (30%, 16%, 54%, respectively) was not significa ntly different from that seen in healthy subjects (31%, 28%, 41%, respectiv ely, p=0.356). These results indicate that ACE plasma activity is increased in untreated O SAS patients. This increased activity may contribute to the pathogenesis of the cardiovascular disease in these patients.