Objective: Variations in the angiotensin converting enzyme (ACE) gene have been implicated in cardiovascular pathology. Therefore, the association between the intima-media thickness (IMT) of the carotid artery and the insertion/ deletion (I/D) polymorphism of the ACE gene was investigated.
Subjects: Three hundred men and 300 women were selected randomly from the middle-aged population living in the town Oulu, Finland, of whom 515 subjects (85.8%) participated.
Methods: The IMT of the carotid arteries was determined by bilateral B-mode ultrasonography. IMT values were adjusted for gender, age, height, plasma low-density lipoprotein cholesterol level, smoking and systolic blood pressure. The I/D polymorphism of the ACE gene was determined by polymerase chain reaction.
Results: Among non-smokers, the subjects with the DD genotype had significantly higher carotid IMT than did those with II or ID. The association was found also in combined IMT plaque values. In the total population the association was weaker and it was absent in current smokers. Genotype could explain 1.3-2.7% of the variance of carotid IMT in non-smokers. No association between the amount or size of carotid plaques and genotype was observed.
Conclusions: Variations at the ACE gene locus contribute to the degree of the early changes in carotid atherosclerosis in the population. The gene effect is, however, masked by stronger effects of environmental factors such as smoking. The lack of association between atherosclerotic plaques and genotypes may reflect different mechanisms being involved in plaque development and early arterial wall thickening.