Angiotensin-converting enzyme gene polymorphism in north Indian population with obstructive sleep apnea

Background: A deletion of 287-bp Alu repeat of angiotensinconverting enzyme (ACE) insertion/deletion (I/D) gene is associated with hypertension. Purpose: The aim of this study is to determine the frequency of ACE (I/D) polymorphism in patients with obstructive sleep apnea (OSA). Method:s Genotyping of ACE (I/D) gene polymorphism and estimation of serum angiotensin-converting enzyme (SACE) activity were done in 813 subjects who underwent polysomnography. Of these, 395 were apneics and 418 were non-apneics. Results: The frequencies of II genotype (OR = 1.8, 95 % CI 1.26-2.60, p=0.001) and I allele (OR = 1.4, 95 % CI 1.13- 1.69, p=0.001) of ACE gene were found to be significantly increased in patients with OSA as compared to patients without OSA. Frequency of II genotype was significantly decreased (OR = 0.46, 95 % CI 0.28-0.77, p=0.003) in OSA patients with hypertension. In contrast, the frequencies of ID (OR=1.80, 95 % CI 1.08-2.99, p=0.024) and DD genotypes (OR=2.15, 95 % CI 1.30-3.57, p=0.003) were significantly increased in this group. The activity of SACE was significantly decreased in the apneic group as compared to the nonapneic group (OR=0.99, 95 % CI 0.98-1.00, p=0.04). Conclusion:s The findings suggest that II genotype confers susceptibility towards development of OSA whereas DD genotype confers susceptibility towards hypertension irrespective of OSA.