Renal function in relation to three candidate genes.
We recently found that femoral intima media thickness, as well as the incidence of hypertension, is influenced by genes encoding the angiotensin-converting enzyme (ACE; insertion/deletion [I/D]) polymorphism, alpha-adducin (Gly460Trp), and aldosterone synthase (-344C/T). By interfering with blood pressure or sodium homeostasis, these genetic polymorphisms also may change renal function. We therefore investigated serum creatinine level, calculated and measured creatinine clearances, and 24-hour urinary protein excretion in subjects previously genotyped for these three polymorphisms. The 1,454 participants drawn at random from the population (64.3% of those invited) were aged 43.4 years and included 744 women (51.2%). Blood pressure, measured by study nurses at subjects' homes, averaged 123/76 mm Hg. Mean values were 90 micromol/L for serum creatinine; 84 and 88 mL/min/1.73 m(2) for calculated and measured (n = 855) creatinine clearances, respectively; and 90 mg/d of protein for proteinuria (n = 556). The prevalence of mild renal dysfunction (creatinine clearance </= 60 mL/min/1.73 m(2)) was nearly 11%. In single-gene analyses with adjustment for significant covariables, the risk for mild renal dysfunction was positively associated with the ACE D allele. However, multiple-gene analyses showed that these associations were restricted to carriers of the mutated alpha-adducin Trp allele (40.1% of all subjects). Findings remained similar after hypertensive patients and women on hormonal therapy were excluded. In this phenotypically more homogeneous subgroup, serum creatinine level was 3.6 micromol/L (P = 0.02) and relative risks for mild renal dysfunction and proteinuria were 1.7-fold (P < 0.001) and 26% (P = 0.02) greater in ACE D subjects than ACE II homozygotes, respectively. The aldosterone synthase T allele did not strengthen genetic associations with the ACE D allele considered alone or in combination with the alpha-adducin Trp allele. Thus, in the present cross-sectional analysis, renal function was slightly but consistently impaired when both the ACE D and alpha-adducin Trp alleles were present. These findings, together with experimental studies and our previous reports on femoral intima media thickness and the incidence of hypertension, constitute a growing body of evidence delineating a clinical entity genetically determined by the risk-carrying ACE D and alpha-adducin Trp alleles.