Reciprocal interactions of obstructive sleep apnea and hypertension associated with ACE I/D polymorphism in males
Received 17 October 2008; received in revised form 17 December 2008; accepted 17 December 2008.
Abstract
Background
The angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism gene contributes to the genesis of hypertension (HTN) and may help explain the relationship between obstructive sleep apnea (OSA) and HTN. However, ACE is a pleiotropic gene that has several influences, including skeletal muscle and control of ventilation. We therefore tested the hypothesis that ACE polymorphism influences OSA severity.
Methods
Male OSA patients (apnea-hypopnea index [AHI]>5 events/h) from 2 university sleep centers were evaluated by polysomnography and ACE I/D polymorphism genotyping.
Results
We studied 266 males with OSA (age=48±13y, body mass index=29±5kg/m2, AHI=34±25events/h). HTN was present in 114 patients (43%) who were older (p<0.01), heavier (p<0.05) and had more severe OSA (p<0.01). The I allele was associated with HTN in patients with mild to moderate OSA (p<0.01), but not in those with severe OSA. ACE I/D polymorphism was not associated with apnea severity among normotensive patients. In contrast, the only variables independently associated with OSA severity among patients with hypertension in multivariate analysis were BMI (OR=1.12) and II genotype (OR=0.27).
Conclusions
Our results indicate reciprocal interactions between OSA and HTN with ACE I/D polymorphism, suggesting that among hypertensive OSA males, the homozygous ACE I allele protects from severe OSA.
aDepartment of Psychobiology, Universidade Federal de São Paulo, Brazil
bPsychobiology and Exercise Research Center, Universidade Federal de São Paulo/UNIFESP, Rua Napoleão de Barros, 925, Vila Clementino, 04024-002 São Paulo, Brazil
cHypertension Unit, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
dSleep Laboratory, Pulmonary Division, Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil
ABSTRACT