No effect of insertion/deletion polymorphism at the ACE locus on normal blood pressure level or variability

Angiotensin I-converting enzyme (ACE) cleaves angiotensin I to angiotensin II, which is the active component in the renin-angiotensin system (RAS). We have studied an insertion/deletion polymorphism in DNA at the ACE locus. In three different series comprising 140, 90 and 136 unrelated individuals we found no evidence of association between genotypes in this insertion/deletion (I/D) polymorphism and level of systolic or diastolic blood pressure. In two series of 130 and 88 monozygotic (MZ) twin pairs, respectively, there was no difference between genotypes in within-pair variation in systolic or diastolic blood pressure. Thus, in these series of healthy people, neither "level gene" nor "variability gene" effects of this insertion/deletion polymorphism were observed.