Myocardial Infarction (MI) was reportedly precipitated by acquired and inherited risk factors including the G/A and 4G/5G polymorphisms within the promoter of the Plasminogen Activator Inhibitor -1 (PAI-1) gene.

to investigate the association between gene polymorphism of the PAI-1 and MI in Tunisian.

PAI-1 G/A was genotyped with polymerase chain reaction — restriction fragment length polymorphism (PCR-RFLP) while PAI-1 4G/5G promoter genotype was established by allele specific polymerase chain reaction amplification of genomic DNA. This study was performed in 305 myocardial infarction patients and 328 unrelated healthy controls. All subjects clinical features and PAI-1 and t-PA activity were tested.

There were two polymorphisms within the promoter (a G/A single base substitution polymorphism at -844bp upstream from the start of transcription and an insertion (5G)/deletion (4G) polymorphism at position — 675). Higher frequency of the 4G allele (p<0.001; O.R.=1.929), but a lower frequency of the 5G allele (p<0.001; O.R.=0.356), were seen in patients vs. controls. The frequencies of the -844G (p<0.001; O.R.=0.314) allele was lower than -844A allele (p<0.001; O.R.=4.076) in patients versus controls. Furthermore significant elevation in plasma PAI-1 levels (88.43±52.85ng/ml vs. 62.18±39.31ng/ml; p <0.05) was seen among patients.

This study indicates that the risk of MI was notably high in 4G carriers and A carriers with elevated plasma PAI-1, and were associated with reduced t-PA levels.