Similar frequencies of renin gene restriction fragment length polymorphisms in hypertensive and normotensive subjects. A prospective study was conducted to compare the frequency of renin gene polymorphisms in normotensive and hypertensive subjects. Hypertensive (n = 102, blood pressure 168 +/- 17/103 +/- 9 mm Hg) and normotensive (n = 120, blood pressure 122 +/- 10/75 +/- 9 mm Hg) subjects were white, had similar age and sex distributions (hypertensive group, 45 +/- 10 years old and 52% female; normotensive group, 44 +/- 9 years old and 55% female) and similar body mass index (hypertensive group, 23.2 +/- 2.6; normotensive group, 22.5 +/- 2.4 kg/m2, p = 0.048). The familial susceptibility to hypertension was defined as at least one parent and one sibling who were hypertensive before age 65; subjects in the normotensive group had no familial history of hypertension. Renin gene polymorphisms located throughout the renin gene were identified by using three restriction enzymes (Taq I, HinfI, HindIII). For each polymorphic restriction site, allele frequencies were similar in the hypertensive and the normotensive groups. In the absence of parental genotypes, the haplotype frequencies combining the three restriction fragment length polymorphisms were estimated by using maximum likelihood techniques and were similar in both groups (hypertensive group, 0.429, 0.277, and 0.177; normotensive group, 0.453, 0.245, and 0.195 for the three most common haplotypes). A rare haplotype detected by Taq I/Hind III was apparently more frequent in the hypertensive than in the normotensive group (hypertensive group, tH 0.086, th 0.022; normotensive group, tH 0.038, th 0.050), but the difference was not statistically significant. In conclusion, no association between renin gene polymorphisms and essential hypertension was demonstrated in the present study. 