Aldosterone synthase gene (CYP11B2) C-334T polymorphism, ambulatory blood pressure and nocturnal decline in blood pressure in the general Japanese population: the Ohasama Study

Objective The C-344T polymorphism in the 5'-flanking region of the aldoster one synthase (CYP11B2) gene has been suggested to be associated with hypert ension and disturbed circadian blood pressure (BP) rhythm through its effec t on aldosterone synthesis. However, previous findings on this topic have b een inconsistent. Design A cross-sectional study. Subjects and methods We investigated the CYP11B2 C-344T genotype in 802 sub jects, aged 40 and over, in a Japanese community, who gave written informed consent and were monitored for 24 h ambulatory BP. Results The frequencies of the CC, CT, and TT genotypes in these Japanese s ubjects were 0.14, 0.44, and 0.42, showing a higher frequency of the T alle le (0.64) than in Caucasians. Although there was no significant difference in 24 h ambulatory BP levels among the genotypes, the nocturnal decline in BP was significantly greater in the CC homozygous subjects than in other su bjects (P = 0.0065 for systolic and P = 0.031 for diastolic decline in noct urnal BP). Detailed analyses demonstrated that this association was signifi cant only in aged (60 years and over) or male subjects. The prevalence of p revious cardiovascular disease was significantly less in these subjects wit h the CC genotype than in those with the TC and TT genotypes, although age, body mass index, male gender, smoking, use of alcohol and antihypertensive medication did not differ among the three genotypes. There was no signific ant difference among the three genotypes in biochemical and hormonal parame ters. Conclusion Although the C-344 T polymorphism of CYP11B2 did not directly in fluence the level of 24 h BP, the CC genotype was associated with decreased nocturnal BP in elderly or male Japanese. Since prevalence of previous car diovascular disease was significantly less in homozygous CC subjects, great er nocturnal BP decline in this genotype appears to be beneficial in the ci rcadian BP rhythm. J Hypertens 19:2179-2184 (C) 2001 Lippincott Williams & Wilkins.