Antiphospholipid syndrome (APS, Hughes syndrome)

Antiphospholipid syndrome is a condition in which the immune system produces antibodies, most importantly against a protein called beta-2 glycoprotein I, that appear to increase the tendency of blood to clot and to disrupt normal placental function during pregnancy. Current understanding describes a broader process of thrombo-inflammation behind the clotting risk, involving activation of platelets, blood vessel lining cells, and the complement system. APS can occur on its own or alongside another autoimmune condition such as lupus.

Research describes it as an uncommon condition, with studies estimating incidence and prevalence in the general population at roughly 1 to 2 new cases and 40 to 50 existing cases per 100,000 people, while antiphospholipid antibodies themselves are found more often, in a meaningful share of people with unexplained pregnancy loss, stroke, or blood clots.

Common signs

Blood clots in the legs or lungs, stroke or other clot-related events, recurrent miscarriage or other pregnancy losses, a lacy purplish skin pattern (livedo reticularis), and sometimes low platelets or migraines.

This is a plain-language summary for orientation, not a diagnosis. Mechanisms are described as current understanding, not settled fact. Work with your own clinician for your care.