DECREASE WITH AGE IN FREQUENCY OF THE HOMOZYGOUS DELETIONAL ANGIOTENSIN-CONVERTING ENZYME GENOTYPE IN HYPERTENSIVE PATIENTS

1. Angiotensin-converting enzyme (ACE) genotypes in hypertensive patie nts were studied in order to delineate their cardiovascular risk due t o the ACE gene. We hypothesized that the distribution of ACE genotypes may change with age because of the risk of myocardial infarction asso ciated with the homozygous deletional (DD) genotype. 2. A total of 223 subjects were recruited from the Hypertension Outpatient Clinic of th e Sai Ying Pun Hospital with consent. They consisted of 75 patients wi th newly diagnosed or documented hypertension, 46 patients with ischae mic heart disease and 102 normal controls. Genomic DNA was extracted f rom peripheral leucocytes and amplified by polymerase chain reaction. Insertion (I) or deletion (D) alleles were identified after electropho resis, The frequencies of ACE genotypes and alleles were measured in t hree age groups: < 50 years, 50-59 Sears and greater than or equal to 60 years. 3. A significant correlation between ACE genotype and age wa s found (P = 0.03), The relative frequency of the D allele in those un der 50 years of age was similar in controls and hypertensive patients (0.40 vs 0.41; P = 0.94), but was significantly lower in patients grea ter than or equal to 50 years compared with those patients <50 years o f age (0.22 vs 0.41; P = 0.01), 4. The observed decrease in frequency of the DD genotype in older hypertensive patients is consistent with t he increase in cardiovascular risk associated with the D allele and ra ises the possibility that the DD genotype may increase the risk of pre mature death, at least in the population studied, Key words: angiotens in-converting enzyme, gene, hypertension, polymorphism.