Centro Hospitalar de São João

Introduction: The development of thrombosis is multifactorial in Antiphospholipid Syndrome (APS), with other inherited and acquired risk factors influencing the thrombotic profile. While inherited thrombophilia are still rare among APS patients, some works suggest a higher prevalence of C and S Proteins deficiencies and factor V Leiden mutation in these patients compared to the general population. Nevertheless, the exact frequency and clinical implications of the presence of these prothrombotic factors in APS are still poorly characterized. Methods: All patients followed in an Autoimmune Diseases consultation with a diagnosis of APS fulfilling the Sidney revised criteria were included. Data regarding inherited thrombophilia was collected - Activated protein C resistance (APCR); Leiden V Factor mutation; C and S proteins deficiencies; Prothrombin G20210A mutation; and Antithrombin III deficiency. Results: A total of 75 patients were analyzed, with 65.3% corresponding to primary APS. The mean age of the study sample was 40 ± 9.4 years and the mean duration of disease was of 6.57 years ± 4.78 years. Seventeen (22.7%) patients exhibited an inherited thrombophilia: 9 (16.1%) S protein deficiency, 5 (10.2%) APCR, 5 (8.5%) antithrombin III deficiency, 4 (7.1%) C protein deficiency, 2 (4.5%) prothrombin G20210A mutation and 1 (2.0%) Leiden V factor mutation. The presence of inherited thrombophilia did not show statistically significant association with clinical manifestations or recurrence of events. Conclusion: Although with a significant prevalence in the studied sample, the presence of inherited thrombophilia did not display a significant clinical implication. However, positive findings might have been undermined due to the reduced sample size originating an underpowered study.