SERPINE1 and Arterial thrombosis: In accordance with the result of a previous study performed by Tassies et al. [16], our patients did not have a higher risk of the PAI-1 4G mutation when we compared their genotypic distribution with the healthy controls (p = 0.443); however, our results were different to the results from the study performed by Tassies et al. [16] as they reported that the presence of the 4G allele of the 4G/5G polymorphism in the PAI-1 gene is a risk factor for the development of arterial thrombosis in APS patients.