Study Of Obstructive Sleep Apnea Syndrome And Narcolepsy: Pathogenesis

Part I: Angiotension I Converting Enzyme Gene Polymorphism in Chinese Patients With Obstructive Sleep Apnea SyndromeObjective Obstructive sleep apnea syndrome (OSAS) is a complex, multifactorial, and polygenetic disease that is thought to result from an interaction between an underlying genetic background and several environmental factors. OSAS has identified as an important risk factor for hypertension, myocardial infraction, stroke, and sudden death. The strongest association demonstrated to date is between OSAS and hypertension, but a direct etiologic link between the two disorders has not been established definitively. We therefore hypothesized that if essential hypertension causes sleep apnea, the DD genotype is a significant risk factor for EH, then one would expect the DD genotype is also an independent risk factor for OSAS. Therefore, the relationship of an insertion/deletion (I/D) polymorphism of the angiotension-converting enzyme (ACE) gene to obstructive sleep apnea sleep (OSAS) patients and the control subjects was investigated. Methods Genomic DNA was extracted from blood samples and amplified by polymerase chain reaction (PCR). PCR primers were flanking the polymorphic region in intro 16 of the ACE gene. Results The distribution of the DD, ID, and II ACE genotypes was 16%, 52%, and 32% in the control subjects and 0%, 56%, and 44% in OSAS patients, respectively. The estimated frequencies of the insertion allele and the deletion allele were 58%, 42% in the control subjects and 72%, 28% in OSAS patients, respectively. The differences were statistically significant(P<0.05). There was no significant difference (p>0.05) in the mean value of neck circumference, BMI, WHR, SBP, and DBP between II and ID genotypes of OSAS patients. But, the OSAS patients with I/I genotype had significantly longer apnea duration (p<0.05), lower minimum SaO₂ (P<0.05) and greater AHI (p<0.05) than did the OSAS patients with I/D genotype. Conclusion These results indicate that the II genotype and I allele are a risk factor for OSAS in Chinese. It is possible that sleep apnea causes essential hypertension.