Insertion/deletion polymorphism of angiotensin converting enzyme gene in Korean hypertensive adolescents

Abstract

The essential role of the renin-angiotensin system (RAS) in controlling blood pressure has been well established. Genes encoding components of the RAS have been proposed as candidate genes that determine genetic predisposition to hypertension and the risk of developing cardiovascular complications. The purpose of this study was to analyze angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphisms in Korean hypertensive adolescents, and to determine the association between ACE genotype and cardiovascular risk. Forty hypertensive adolescents (16-17 years old, systolic blood pressure (BP) > or =140 mm Hg and/or diastolic BP > or =90 mm Hg) and a control group of twenty normotensive adolescents were included in the study. Obesity index (OI) and body mass index (BMI) were calculated. Skin fold thickness and arm circumference were also measured. Fat mass and fat distribution were analyzed by bioelectrical impedance. Blood pressure was measured at resting state by oscillometric methods. Serum aldosterone, renin, insulin, ACE, homocysteine, vitamin B12, and folate levels were evaluated after a fasting period of 12 h. The carotid intima-media thickness (IMT) and carotid artery diameter were measured by carotid ultrasound. Pulse wave velocity (PWV) and ankle-brachial index (ABI) were also measured. Polymerase chain reaction (PCR) was conducted to amplify DNA from blood samples of each individuals to analyze ACE I/D polymorphism. Genotype frequencies of I/I were 37.5%, I/D 45.0% and D/D 17.5%. Serum ACE levels were 33.5 +/- 8.7 U/l in I/I genotype, 48.6 +/- 19.8 U/l in I/D genotype and 61.4 +/- 22.7 U/l in D/D genotype, which showed that ACE levels were significantly higher in those with D/D or I/D genotype than in I/I genotype. Carotid IMT was significantly greater in D/D group than in I/I group. In conclusion, the D allele is associated with the increased level of ACE in Korean hypertensive adolescents.