What Is Antiphospholipid Syndrome
(APS)?
Antiphospholipid syndrome (APS), also known as
antiphospholipid antibody syndrome and sometimes Hughes
syndrome, is a disorder characterized by elevated levels of
multiple different antibodies (proteins produced by the body to
fight off foreign substances) that are associated with both
arterial and venous thrombosis (clots in the arteries and
veins).
There are two primary classes of antiphospholipid (aPL)
antibodies, the antibodies associated with APS. These are
called anticardiolipin antibodies and the lupus anticoagulant,
and are directed against specific molecules.
These aPL antibodies appear to be mainly directed against
two particular molecules: beta-2-glycoprotein I (ß2GPI, a
normal protein found in the blood whose function is unknown)
and another molecule known as prothrombin (a normal blood
protein that binds to phospholipids and plays a very important
role in blood clotting).
These aPL antibodies were first noted in a group of people
who had positive tests for syphilis without signs of
infection.
It was then noticed that some individuals who continued to
have false-positive tests for syphilis went on to develop
systemic lupus erythematosus (SLE) and other similar
conditions.
Later studies found a protein called the lupus anticoagulant
in a number of individuals with SLE. A case report in 1956
described an individual with recurrent pregnancy loss,
thrombophlebitis (inflammation of a vein related to a blood
clot) and lupus anticoagulant.
The work of Dr. Graham Hughes and his colleagues in the
1980s provided further understanding of APS, including the
introduction of testing for anticardiolipin antibodies.
Health
Related Websites
The National Cancer
Institute
The National Eye
Institute
The National Heart, Lung,
and Blood Institute

National Institute on
Aging

National Institute of
Allergy and Infectious Diseases

National Institute of
Arthritis and Musculoskeletal and Skin Diseases

National Institute of
Diabetes and Digestive and Kidney Diseases

National Institute on Drug
Abuse

National Institute of Mental
Health

National Institute of
Neurological Disorders and Stroke
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