Aetiology

The cause of the disease is largely unknown. Evidence suggests that the aetiology is multifactorial (1).

There is a familial association in some cases of APS. HLA studies suggest DR7, DR4 and DQw7 plus DRw53 are risk factors.

The aPL antibody is targeted to the combination of cardiolipin with a plasma protein called beta-glycoprotein I.

In vivo aPL has a procoagulant effect on:

• platelet membranes
• endothelium
• prothrombin, protein C and protein S

aPL is found in the serum of 30% of patients with SLE, in this context it is termed "lupus anticoagulant".

Reference:

• (1) Cohen D et al. Diagnosis and management of the antiphospholipid syndrome. BMJ. 2010;340:c2541