A study on angiotensin-I converting enzyme polymorphism in CAPD patients

To clarify the role of genes related to angiotensin-I converting enzyme (ACE), the author investigated polymorphism of the ACE gene in 60 patients undergoing chronic ambulatory peritoneal dialysis (CAPD) and 50 patients undergoing hemodialysis (HD). One hundred healthy subjects were used as controls. The polymorphism was classified into three genotypes, II, ID and DD, according to insertion (I) and deletion (D) using the polymerase chain reaction method. In dialysis patients (CAPD or HD, n = 110), 21.8% had the II genotype, 48.2% the ID genotype, and 30.0% the DD genotype. There was a significant difference in allele frequency between normal subjects (n = 100) (J = 0.63, D = 0.37) and dialysis patients (I = 0.46, D = 0.54) (chi 2 = 12.321, p < 0.001). The mean plasma ACE activity was 9.9 +/- 1.6 IU/l in CAPD patients with the II genotype, 11.6 +/- 4.7 IU/l in CAPD patients with the ID genotype, and 14.5 +/- 3.5 IU/l in CAPD patients with the DD genotype. The mean rate of decrease in residual urinary volume was 0.8 +/- 0.7% per month in CAPD patients with the II genotype 1.4 +/- 1.3% per month in CAPD patients with the ID genotype, and 2.5 +/- 2.0% per month in CAPD patients with the DD genotype. These data showed a significant decrease in urinary volume in CAPD patients with the DD genotype (p < 0.05). The mean rate of decrease in residual urinary volume was positively correlated with the plasma ACE activity (r = 0.13389, p < 0.02). In CAPD patients, the mean cardiothoracic ratio was 46.6 +/- 3.5% in cases with the II genotype, 47.6 +/- 5.5% in cases with the ID genotype, and 52.9 +/- 8.4% in cases with the DD genotype. These data indicated significant cardiac enlargement in DD genotype cases. It can be concluded that CAPD patients with the DD genotype lost their residual renal function more rapidly and had a larger heart, than patients with the other genotypes.