Associations of the –344T>C polymorphism of CYP11B2 gene with 24-hour blood pressure profiles in middle-aged women with essential hypertension

Abstract

Background In this cross-sectional study, we assessed the impact of –344T>C polymorphism of the CYP11B2 gene which encodes aldosterone synthase on 24-hour blood pressure patterns.
Material and methods The study was performed in 137 females with essential hypertension aged 42−60 years. We measured plasma aldosterone level and renin activity (PRA), fasting glucose, lipid profiles and 24-hour urinary sodium and potassium excretion. Based on 24-hour blood pressure monitoring we identified cases with dipping and non-dipping patterns of blood pressure.
Results Mean PRA and aldosterone levels and aldosterone-to-renin ratio (ARR) were within normal range. Non-dipping hypertension was found in 54.3% of patients. Genotype frequencies of TT, CC and CT were 27%, 27% and 46%, respectively. Carriers of the C allele had significantly lower nocturnal blood pressure reduction (P = 0.004) and higher nocturnal systolic (P = 0.02) and diastolic blood pressure (P = 0.044), frequency of non-dipping profile (P = 0.001), and 24-hour urinary potassium excretion (P = 0.047). Urinary sodium excretion was positively correlated with a decrease in nocturnal blood pressure (R = 0.202; P = 0.037). In a multiple regression analysis, ARR and presence of the C allele adjusted for confounding variables were inversely associated with the nocturnal blood pressure decline (b = −0.348; P = 0.022 and b = −0.222; P = 0.018, respectively).
Conclusions In conclusion, in middle-aged females with essential hypertension carrying the C allele we found higher nocturnal blood pressure, lower nocturnal blood pressure reduction, and higher prevalence of non-dipping hypertension than in TT carriers.