CausesBy Mayo Clinic staff
The role of phospholipids
In antiphospholipid syndrome, your body mistakenly produces antibodies against proteins that bind phospholipids, a type of fat present in your blood that plays a key role in clotting (coagulation). Antibodies are specialized proteins that normally attack body invaders, such as viruses and bacteria. When antibodies attack your phospholipid-binding proteins, your blood may clot abnormally.
There are two main classifications of antiphospholipid syndrome:
- Primary. If you have no other autoimmune disorder, such as systemic lupus erythematosus (SLE), you have primary antiphospholipid syndrome.
- Secondary. If you do have lupus or another autoimmune disorder, your antiphospholipid syndrome is secondary.
With secondary antiphospholipid syndrome, the cause is considered to be your lupus or other autoimmune disorder.
The cause of primary antiphospholipid syndrome is unknown. However, some factors are associated with developing antiphospholipid antibodies — though not necessarily developing the syndrome. They include:
- Infections. People with syphilis, HIV infection, hepatitis C and malaria, among others, have a higher incidence of having antiphospholipid antibodies.
- Medications. Taking certain drugs, such as the high blood pressure medication hydralazine, the heart rhythm-regulating medication quinidine, the anti-seizure medication phenytoin (Dilantin) and the antibiotic amoxicillin may lead to an increased risk.(
- Genetic predispositions. Although the disorder isn't considered hereditary, research indicates that relatives of people with antiphospholipid syndrome are more likely to have the antibodies.
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