Objective:
To investigate the relationship between the 4g/5g polymorphism of the type 1 plasminogen activator inhibitor (pai-1) gene and thrombotic manifestations in patients with antiphospholipid syndrome (aps).
Methods:
We studied a total of 247 patients included in the following 4 groups: 70 patients with primary aps, 104 patients with systemic lupus erythematosus (40 with antiphospholipid antibodies [apl] and clinical [secondary] aps, 13 with apl but without clinical aps, and 51 with neither detectable apl nor a history of thrombosis), 14 asymptomatic individuals with apl, and 59 patients with thrombosis but without known thrombosis risk factors. a control group of 100 healthy individuals was also analyzed. pai-1 4g/5g polymorphism was determined by polymerase chain reaction and endonuclease digestion.
Results:
The allele frequency of 4g/5g in controls was 0.47/0.53. there were no differences in allele distribution among patient groups or between patients and controls. however, a higher frequency of the 4g allele was observed in aps patients with versus those without thrombosis (0.57 versus 0.39; p < 0.05) (odds ratio [or] 2.83, 95% confidence interval [95% ci] 1.18-6.76). this higher frequency of the 4g allele was attributable to the higher frequency in patients with versus those without arterial thrombosis (0.64 versus 0.43; p < 0.01) (or 5.96, 95% ci 1.67-21.32), while patients with venous thrombosis had an allele distribution similar to that of those without venous thrombosis (0.49 versus 0.50; p not significant). there was a trend toward higher pai-1 antigen and activity levels in aps patients and controls with the 4g/4g genotype, but this did not reach statistical significance.
Conclusion:
The presence of the 4g allele of the 4g/5g polymorphism of the pai-1 gene may be an additional risk factor for the development of arterial thrombosis in aps.