The angiotensin-converting enzyme(ACE) plays an important role in cardiovascular disease by production of angiotensin Ⅱ and degradation of bradykinin. Cloning of ACE gene revealed an insertion/deletion(I/D) polymorphism according to the presence/absence of a 287 base pair fragment in the 16th intron of ACE gene, and the ACE polymophism was associated with ACE activity. The genotype DD was identified as a risk factor for myocardial infarction in several studies. We analyzed the ACE I/D polymorphism in 62 patients with myocardial infarction and 67 normal subjects.

Genomic DNA from peripheral blood was amplified by polymerase chain reaction and characterized by three ACE genotypes; two insertion alleles(genotype II), two deletion alleles(genotype DD) and heterogenous alleles(genotype ID). ACE activity was determined by spectrophotometric method utilizing the synthetic substrate.

There was no significant difference in ACE polymorphism between patients and normal subjects. But, the frequency of genotype DD was significantly increased in the low-risk group of patients compared with the high-risk group. The multi-vessel disease was more strongly associated with genotype DD, but there was no statistical significance. The ACE activity was strongly associated with ACE polymorphism with the activity being highest in genotype DD. There was no significant difference between patients and control subjects of the same genotype.

There was no significant difference in ACE polymorphism between patients and normal subjects. The frequencies for genotype II, ID, DD were 0.328, 0.537, 0.134, respectively in normal subjects. There was high frequency of genotype II compared with Caucasians. A deletion polymorphism(genotype DD) may increase the risk for myocardial infarction in lowrisk group, and the serum ACE activity was correlated with three genotypes.