Human lipoprotein lipase HindIII polymorphism in young patients with myocardial infarction

We investigated the possibility that the DNA HindIII polymorphism of human lipoprotein lipase (LPL) is associated with the severity of coronary artery disease (CAD) determined by angiography in young patients who survived a myocardial infarction (MI). Conflicting studies have explored the relationship linking CAD severity to the HindIII restriction site polymorphism at the LPL gene locus, and to our knowledge, no data are available from Italy. The patients were aged less than 45 years (mean age, 40.1 ± 3.9 years); 83 were male and four were female. The 87 case-patients had a Q-wave or non-Q-wave infarction (67.3% and 32.7%, respectively); the MI was anterior (50.5%), lateral (41.7%), or inferior (7.8%). Analysis of coronary angiograms showed the absence of critical stenosis in 13.8% and the presence of monovessel disease in 50.6% and multivessel disease in 35.6% of the case-patients. The allelic frequency of the HindIII H(−) and H(+) allele was 0.37 and 0.63, respectively. There was a striking association between the HindIII polymorphism and the number of diseased vessels. The patients with HindIII(+/+) genotypes were significantly more likely to have double- or triple-vessel disease and less likely to have no significantly diseased vessels. In this study, we demonstrated that the homozygous form of the LPL HindIII(+) allele increases the risk of multivessel disease by a factor of 4 in an Italian group of young MI survivors. This association was independent from the smoking status and a positively family history for CAD and hypertension, which are known to predict CAD severity. The discrepancies in the results of these studies are difficult to explain. The lack of homogeneity in the study populations (age at which CAD occurred, number of enrolled patients, and geographical origin) and differences in the assessment of CAD severity may account for these conflicting results.