Investigation of Major Genetic Polymorphisms in the Renin-Angiotensin-Aldosterone System in Subjects with Young-Onset Hypertension Selected by a Targeted-Screening System at University

Abstract

Although polymorphisms in renin-angiotensin-aldosterone (RAA) system genes for angiotensinogen (AGT M235T), angiotensin-converting enzyme (ACE I/D), angiotensin II type 1 receptor (AT1 A/C¹¹⁶⁶), and aldosterone synthase (CYP11B2–344T/C) have been major targets for genetic investigation in association with essential hypertension (EH), the influence of these genetic factors is still to be determined. Because patients with young-onset EH are thought to possess a stronger genetic background than EH patients who show elevated BP relatively late in life, the targeted screening of hypertensive students in Tohoku University was completed for the selection of subjects for genetic investigation. Out of 16,434 students (12,794 males and 3,670 females) younger than 30, 22 students showed a high blood pressure (BP) (systolic and diastolic BP of 140 and/or 90 mmHg or greater, respectively, on two occasions and more than 135 and/or 85 mmHg, respectively, at a third measurement during casual BP measurements at the Tohoku University Health Center. These 22 students were asked to measure their BP at home (HBP). Six of the students had a systolic HBP of more than 135 mmHg and/or a diastolic HBP of more than 85 mmHg, and these students subsequently received medical examinations at Tohoku University Hospital and were diagnosed with EH. Genotyping for the four major genetic polymorphisms mentioned above was performed on the six students with EH and on 12 of the remaining 16 students whose HBP was within the normal range (white coat hypertension: WCH). Neither the EH nor the WCH students showed a different distribution of genotypes and allelic frequencies, compared to those found in the general Japanese population. Hence, the present study suggests that none of the major genetic polymorphisms in the RAA system strongly influence the onset of EH.

Keywords:

• home blood pressure
• casual blood pressure
• essential hypertension
• white coat hypertension
• angiotensin converting enzyme