Aims. We performed a pilot case-control study in order to reveal the possible association between 4G allelic variant and 4G/4G genotype with myocardial infarction previously reported in the world literature in Bulgarian population.

Methods. A total of 54 patients with myocardial infarction and 85 matched healthy controls were genotyped for 4G/5G polymorphism in the PAI-1 gene promoter region. The statistical analysis was performed by χ² test.

Results. In our study we found a trend for higher frequency of the 4G allele (p=0.34) and 4G/4G genotype (p=0.24) in patients with myocardial infarction. We conclude that 4G/4G genotype might be a transmissible risk factor for coronary thrombosis and myocardial infarction in Bulgarian population. Our study has an important limitation of a small study group. Larger studies are needed in order to confirm this promising although preliminary results.

Table. Relative allelic and genotype frequencies of the 4G/5G polymorphism.

	4G/4G	4G/5G	5G/5G	4G	5G
Healthy controls	0,18	0,49	0,33	0,42	0,58
Patients with MI	0,26	0,44	0,30	0,48	0,52