T235 VARIANT OF THE ANGIOTENSINOGEN GENE AND BLOOD-PRESSURE IN THE CHILEAN POPULATION

Background The angiotensinogen gene has recently been linked to essent ial hypertension, A variant within this gene, encoding threonine rathe r than methionine at amino acid position 235, was associated with esse ntial hypertension, However, results of new studies have not confirmed this association, suggesting that ethnic differences may explain the different results. Objective To evaluate whether the T235 variant is a ssociated with a higher incidence of essential hypertension among Hisp anics (a group that has scarcely been evaluated) and to determine whet her T235 is associated with variations in the plasma renin activity or the serum aldosterone level. Patients and method We studied 64 patien ts with essential hypertension and 62 normotensives, matched for age a nd sex, We obtained samples for determinations of plasma renin activit y, serum aldosterone level and genome DNA from all subjects, The genom ic DNA was amplified using the polymerase chain reaction technique and digested by the restriction enzyme streptococcus faecalis (Sfa NI) wh ich cuts M235 only, not T235, Results The patients with essential hype rtension had a higher prevalence of the risk variant T235 (alleles 77/ 128 = 60.2%) than did the normotensive controls (alleles 65/124 = 52.4 %), but the difference was not statistically significant (chi(2) = 1.5 3, P = 0.22). The plasma renin activity levels in hypertensives were n ot statistically different for homozygous T235, heterozygous and homoz ygous M235 (1.0 +/- 0.96, 2.0 +/- 2.25 and 1.55 +/- 1.49 ng/ml per h, respectively, P = 0.5 1), However, when we considered those hypertensi ves with low plasma renin activity levels (<1 ng/ml per h), we found a high prevalence (72.7%) of subjects homozygous for the T235 variant. We found no association between the T235 variant and the serum aldoste rone levels in hypertensive and normotensive subjects, Conclusions We demonstrated that there is a high prevalence of T235 variant in our Hi spanic population. The slight difference between prevalences of T235 v ariant among hypertensive and normotensive subjects that we found was not statistically significant and did not permit us to establish an as sociation between T235 variant and essential hypertension, We believe that only studying a larger cohort of subjects could show whether ther e is a quantitative effect of the T allele on plasma renin activity le vels. (C) 1998 Lippincott-Raven Publishers.