ANGIOTENSIN-CONVERTING ENZYME AND ANGIOTENSINOGEN GENE POLYMORPHISMS,PLASMA-LEVELS, CARDIAC DIMENSIONS - A TWIN STUDY

We tested the hypotheses that angiotensin-converting enzyme insertion/ deletion (I/D) and angiotensinogen 235 methionine/threonine (M/T) subs titution gene polymorphisms influence angiotensin-converting enzyme an d angiotensinogen serum concentrations and cardiac dimensions in 91 mo nozygotic and 41 dizygotic twin pairs. Cardiac dimensions were determi ned echocardiographically. Angiotensin-converting enzyme levels were 2 4 +/- 11, 43 +/- 18, and 58 +/- 24 U/L for the II, ID, and DD genotype s, respectively (P < .01). Posterior wall thickness was 8.1 +/- 1.3, 8 .6 +/- 1.7, and 8.9 +/- 1.9 mm for these genotypes (P < .05). Angioten sin-converting enzyme levels were correlated with posterior wall thick ness (r = .15, P < .05). The intrapair differences in angiotensin conv erting enzyme levels for monozygotic, concordant dizygotic, and discor dant dizygotic twins were 1.36 +/- 1.6, 1.86 +/- 1.6, and 17.25 +/- 4. 3 U/L, respectively. The angiotensinogen M/T genotypes exerted no infl uence on cardiac dimensions or on angiotensinogen concentrations. The additive genetic effect on angiotensin-converting enzyme levels (0.49) , on posterior wall thickness (0.26), and on septum thickness (0.37) w as significant (P < .01), although shared and nonshared environmental effects were also identified. Our data confirm the impressive effect t hat the angiotensin-converting enzyme D allele exerts on angiotensin-c onverting enzyme plasma levels. Furthermore, our data also suggest tha t the angiotensin-converting enzyme gene locus is primarily responsibl e for angiotensin-converting enzyme plasma levels. Our twin study also indicates that the angiotensin-converting enzyme gene locus is geneti cally linked to posterior wall thickness. The correlation between angi otensin-converting enzyme levels and posterior wall thickness suggests that this effect is exerted by angiotensin-converting enzyme. We were unable to demonstrate genetic linkage between the angiotensinogen gen e locus and cardiac dimensions in this study.