Clinically important antiphospholipid antibodies (those that arise as a result of the autoimmune process) are associated with thrombosis and vascular disease. The syndrome can be divided into primary (no underlying disease state) and secondary (in association with an underlying disease state) forms.Anti-ApoH and a subset of anti-cardiolipin antibodies bind to ApoH. ApoH inhibits protein C, a glycoprotein with important regulatory function of coagulation (inactivates Factor Va and Factor VIIIa). Lupus anticoagulant antibodies bind to prothrombin, thus increasing its cleavage to thrombin, its active form.In APS there are also antibodies binding to protein S, which is a co-factor of protein C. Thus, anti-protein S antibodies decrease protein C efficiency.Annexin A5 forms a shield around negatively charged phospholipid molecules, thus reducing their availability for coagulation. Thus, anti-annexin A5 antibodies increase phospholipid-dependent coagulation steps.The lupus anticoagulant antibodies are those that show the closest association with thrombosis; those that target β2glycoprotein 1 have a greater association with thrombosis than those that target prothrombin. Anticardiolipin antibodies are associated with thrombosis at moderate to high titres (over 40 GPLU or MPLU). Patients with both lupus anticoagulant antibodies and moderate or high titre anticardiolipin antibodies show a greater risk of thrombosis than with one alone.The increased risks of recurrent miscarriage, intrauterine growth restriction and preterm birth by antiphospholipid antibodies, as supported by in vitro studies, include decreased trophoblast viability, syncytialization and invasion, deranged production of hormones and signalling molecules by trophoblasts, as well as activation of coagulation and complement pathways.
Based on this statement, Definite CAPS diagnosis requires:

a) Vascular thrombosis in three or more organs or tissues and
b) Development of manifestations simultaneously or in less than a week and
c) Evidence of small vessel thrombosis in at least one organ or tissue and
d) Laboratory confirmation of the presence of aPL.VDRL, which detects antibodies against syphilis, may have a false positive result in aPL-positive patients (aPL bind to the lipids in the test and make it come out positive), although the more specific test for syphilis, FTA-Abs, that use recombinant antigens will not have a false-positive result. Treatment
In people without symptoms, no treatment is required. In people with antiphospholipid antibody-associated thrombosis, anticoagulants such as warfarin are used to prevent further thrombosis. If warfarin is used, the INR is kept between 2.0 and 3.0. Direct-acting oral anticoagulants may be used as an alternative to warfarin, but not in people who are "triple positive" with all types of antiphospholipid antibody (lupus anticoagulant, anticardiolipin antibody and anti-β2 glycoprotein I antibody).Anticoagulation appears to prevent miscarriage in pregnant people. In pregnancy, low molecular weight heparin and low-dose aspirin are used instead of warfarin because of warfarins teratogenicity. People with recurrent miscarriages are often advised to take aspirin and to start low molecular weight heparin treatment after missing a menstrual cycle. In refractory cases plasmapheresis may be used. Prognosis
The long-term prognosis for APS is determined mainly by recurrent thrombosis, which may occur in up to 29% of patients, sometimes despite antithrombotic therapy.