Objective: The insertion (I)/deletion (D) polymorphism of the angiotensin-converting enzyme (ACE) gene has been associated with an increased risk of cardiovascular diseases. In patients with primary pulmonary hypertension, the homozygous ACE DD genotype is more prevalent than the non-DD genotype. However, the relationship of ACE gene polymorphism to secondary pulmonary hypertension remains unclear, and ethnicity may be one of the factors that can modulate the effects of ACE genotypes reported in different studies. We hypothesized that in patients with chronic obstructive pulmonary disease (COPD) the presence of the D allele in the ACE gene polymorphism is associated with increased pulmonary artery pressure (Ppa).
Patients and methods: Bodyplethysmography was used to assess lung function in 66 consecutive patients with COPD; pulmonary artery pressures were determined using echocardiography. ACE gene I/D polymorphism was identified with the polymerase chain reaction. 118 healthy persons served as the control group. All patients and controls were Caucasian. Genotype II was identified in 15 patients with COPD, genotype ID in 31 and genotype DD in 20. In the control group, genotype II was identified in 19 persons, genotype ID in 68 and genotype DD in 31. The distribution of ACE gene polymorphism did not differ between patients and the control group.
Results: In patients with COPD, no differences were seen between the three genotype groups in mean age, smoking history, hemoglobin concentrations or ventilometric or blood gas variables. Both systolic and mean Ppa differed significantly between the II, ID and DD groups (Systolic Ppa: 24.4 +/- 2.2 versus 31.3 +/- 2.5 and 36.7 +/- 3.9 mm Hg, respectively, ANOVA, p < 0.05; Mean Ppa: 13.0 +/- 1.5 versus 17.5 +/- 1.4 and 21.2 +/- 2.8 mm Hg, respectively, ANOVA, p < 0.05). In multiple linear regression analysis, the I/D ACE gene polymorphism (p < 0.05), SaO2 (p < 0.05) and the duration of COPD (p < 0.02) were independent predictors of systolic and mean Ppa.
Conclusion: The results of the study suggest that I/D ACE gene polymorphism is linked to pulmonary artery pressure in Caucasian patients with COPD.