Polymorphism of the ACE Gene in Dialysis Patients: Overexpression of DD Genotype in Type 2 Diabetic End-Stage Renal Failure Patients

Abstract

The angiotensin-converting enzyme (ACE) gene DD homozygote has been suggested to be a significant risk factor for the progression of diabetic nephropathy. We analyzed clinical parameters and ACE genotype distribution between type 2 diabetic patients at the extremes of renal risk, i.e. an end-stage renal failure (ESRF) group (n = 103, group 1) who were on dialysis therapy due to progression of diabetic nephropathy, and a no progression group (n = 88, group 2) who had maintained normal renal function and normoalbuminuria for more than 15 years. There were no significant differences in age, sex, body mass index, HbA1c level, or lipid profiles between the two groups (p > 0.05). Group 1 had a significantly higher prevalence of hypertension [group 1: 82.5% (85/103) vs. group 2: 50.0% (44/88), p < 0.05] and diabetic retinopathy [group 1: 103/103 (100%) vs. group 2: 28/88 (31.8%), p < 0.05] than group 2. Daily urinary albumin excretion was also higher in group 1 than in group 2 [group 1: 2873 ± 2176 mg/day vs. 12 ± 7 g/day, p < 0.05]. The frequencies of the DD, ID, and II genotypes of the ACE gene in group 1 and group 2 were 26.2%, 47.6%, and 26.2%, and 7.9%, 57.9%, and 34.2%, respectively. The ACE genotype frequencies between the two groups were significantly different according to a chi-square test with Bonferroni's correction (p = 0.004). The presence of the DD genotype increased the risk of ESRF 4.286-fold compared to the II genotype [odds ratio 4.286, 95% CI 1.60-11.42, p = 0.005]. The frequency of the D-allele was higher in both male and female patients in group 1 compared to group 2, but reached statistical significance only in males [male, group 1: 50.8% vs. group 2: 35.0%, p = 0.018, female, group 1: 48.8% vs. group 2: 39.5%, p = 0.231]. This study, although limited by sample size, showed that type 2 diabetic ESRF patients more frequently expressed the DD genotype. These findings may substantiate the previously noted relationship between the ACE DD genotype and the progression of diabetic nephropathy in Korean type 2 diabetic patients.