Polymorphism insertion/deletion of the ACE gene and ambulatory blood pressure circadian variability in essential hypertension

Objective The objective of the present study was to analyze the influence o f the insertion/deletion (I/D) polymorphism of the angiotensin-converting e nzyme on ambulatory blood pressure values and circadian variability in untr eated patients with hypertension. Material and methods Ninety-nine essential hypertensive patients, less than 50 years old (mean age 39.5 +/- 7.0 years), previously untreated with anti hypertensive drugs were included, Twenty-four hour ambulatory blood pressur e monitoring (ABPM) was performed with a Spacelabs (90202 and 90207) monito r, during a regular working day in unrestricted ambulatory conditions. The I/D polymorphism of the ACE was determined by PCR. Results The distributions of genotypes were in Hardy-Weinberg equilibrium: I=17 (17%), ID=41 (41.5%), DD=41 (41.5%). No significant differences were p resent among the groups in terms of age, sex, and biochemical and lipid pro files, The average of 24-h ambulatory blood pressure was slightly higher in patients with the DD genotype as compared with patients with the II and ID genotypes. This was the result of higher nighttime blood pressure values, because no differences in blood pressure were observed during daytime. The systolic blood pressure (SBP) day:night ratio, as an estimate of circadian variability, was significantly lower in subjects homozygous for the D allel e than it was in patients carrying the I allele (1.13 +/- 0.09 vs. 1.17 +/- 0.08, P= 0.014), The subjects in the lowest tertile of the SEP day:night r atio, exhibited a higher frequency of the D allele when compared with those in the middle tertile (0.74 vs. 0.59, P < 0.05) or with those in the highe st tertile (0.74 vs. 0.54, P < 0.01). By using two-way ANOVA with repeated measures, significant differences in SEP variation over time were observed when comparing homozygous for the D allele with subjects carrying the \ all ele (F = 2.11, P = 0.002). Conclusions Among the genotypes of the I/D polymorphism, subjects carrying DD genotype showed a blunted decline of the physiological nocturnal fall of blood pressure that was significant for SEP. (C) 2001 Lippincott Williams & Wilkins.