White coat hypertension, microalbuminuria and renin-angiotensin-aldosterone system gene variants in adolescents

Abstract

White coat hypertension is frequently found in pediatric hypertensive patients. 45% of hypertensive adolescents attending our clinic were white coat hypertensive and all of them were offspring of essential hypertensive parents. Family history of hypertension and blood pressure in early life are major predictors of hypertension in adulthood. Therefore, the aim of this study was to evaluate if isolated office high blood pressure is associated to other risk factors reported in essential hypertension, such as microalbuminuria and gene alleles related to essential hypertension. In 311 adolescent offspring of hypertensive parents: 180 normotensive (N) (age 13 ± 2.9, BMI 24.8 ± 5.7, 114 males); 60 white coat hypertensives (WCH) (age 13.6 ± 2.3, BMI 23.3 ± 6.4, 31 males); and 71 essential hypertensives (EH) age 13.3 ± 2.9, BMI 24.1 ± 5.6, 53 males) we evaluated microalbumine excretion in a 24 hour urine collection, and polimorphisms of the renin-angiotensin-aldosterone system gene components: ECA (I/D), M235T and T174M of the angiotensinogen gene (AGT), AT1R (A1166C) and CYP11b2 (C344T) by PCR/RFLP/ASO. ABPM was done with an Accutracker II monitor during 24 hours. Office and daytime ambulatory blood pressures (X±SD) were: N: 112/68 ± 12/9 and 115/63 ± 8/6; WCH: 135/76 ± 9/9 and 117/63 ± 7/6; and EH: 137/78 ± 11/12 and 134/73 ± 9/9 mm Hg. Microalbuminuria in WCH was not different from N and significantly lower than in EH (p<0.03): N 14.5 ± 2.8; WCH 6.6 ± 1.1 and EH 23.4 ± 8.7 ug/day. TT variant of the M235T of AGT was more prevalent in EH (OR: 2.43; 95%CI: 1.06-5.56, p<0.04). A1166 polimorphism of the AT1R gene correlated with systolic and diastolic blood pressure load in ABPM (p<0.005 and 0.05, respectively). No associations were found with the other gene variants studied. In summary: no differences in microalbuminuria and gene variants of the renin-angiotensin-aldosterone system were found between white coat hypertensive and normotensive offspring of hypertensive parents. Systolic and diastolic blood pressures were higher in adolescents with the A allele of the AT1R A1166C. The T allele of the M235T polimorphism of AGT was more prevalent in essential hypertension. These findings suggest that the genetic background of normotensive and white coat hypertensive offspring of hypertensive parents may be different from that of essential hypertensives.