T+31C polymorphism of angiotensinogen gene and nocturnal blood pressure decline: the Ohasama study

Abstract Background We assessed the association between several polymorphisms of angiotensinogen gene (AGT) and essential hypertension using ambulatory blood pressure (BP). Methods We recruited 802 subjects in a rural Japanese community who were aged >40 years and who gave written informed consent for monitoring of their ambulatory BP and genetic analysis (the Ohasama Study). As a polymorphism of AGT, T+31C, which is in complete linkage disequilibrium with M235T, was determined using the TaqMan polymerase chain reaction method. Results The genotype distribution of AGT/T+31C in the Ohasama Study was similar to that in another large Japanese population. Although there was no significant difference in 24-h and daytime ambulatory BP values, the nighttime BP was significantly lower in the subjects with TT, resulting in greater decline of nocturnal systolic (P = .090) and diastolic (P = .025) BP in subjects with TT. Conclusions AGT/T+31C is associated with the circadian BP variation but not with BP level in the Japanese general population.