The 'antiphospholipid antibodies'. Antibodies are produced by the body's immune system to fight infection from bacteria and viruses. In some diseases, the immune system produces antibodies that mistakenly attack the body's own tissues. The result is an autoimmune disease, eg antiphospholipid syndrome. Phospholipids are phosphorus-containing fat molecules found throughout the body, particularly in the surrounding coat of cells - the cell membranes. The 'antiphospholipid antibodies' target the body's own phospholipids, and also proteins that bind to phospholipids.

If the symptoms of the APS Antiphospholipid Syndrome (Hughes' syndrome) occur, this is known as primary antiphospholipid syndrome. The secondary form occurs in association with another autoimmune disease, usually systemic lupus erythematosus. Both types are more common in women.

Symptoms relate to abnormal clotting. Most commonly clots can develop in the veins of the legs (deep vein thrombosis), resulting in a swollen, painful leg, with the swelling usually starting in the calf. These clots in the leg may happen once, or several times. Clots may also occur in the lung (pulmonary embolus), sometimes following a clot in the leg, which breaks off and travels in the circulation until it lodges in part of the blood supply to the lung. A clot in the lung may lead to shortness of breath, chest pain made worse by breathing in, or coughing up a small amount of blood. Some clots occur in patients soon after starting on the oral contraceptive pill (estrogen-containing types).

Veins in other parts of the body may clot, including the eye, the kidney, the liver, and the adrenal gland.

Depending on where it occurs, clotting within an artery can result in a stroke, heart attack, or blockage of the blood supply to a limb, possibly leading to gangrene. Such arterial diseases occur commonly from arteriosclerosis in old age, but in the antiphospholipid syndrome they can happen at a much younger age. Hence a patient under 50 who has a stroke or a heart attack should be tested for the antiphospholipid syndrome.

Ladies with APS Antiphospholipid Syndrome (Hughes' syndrome) are at increased risk of miscarriage. Clots may form in the placenta leading to an inadequate blood supply to the fetus. Miscarriages in antiphospholipid syndrome usually occur in the second or third trimester (week 12 or later), but can sometimes occur in the first trimester. Fifteen per cent of women with three or more consecutive miscarriages have positive antiphospholipid syndrome tests. There are patients with antiphospholipid syndrome who have successful pregnancies without treatment, though there is a higher risk of complications towards the end of pregnancy, including pre-eclampsia, intrauterine growth retardation (slowing down of the baby's growth in the uterus), and premature delivery.

APS Antiphospholipid Syndrome (Hughes' syndrome) patients report a higher incidence of headaches, including migraines. A proportion of patients have memory loss, or more subtle abnormalities. Epilepsy is commoner in antiphospholipid syndrome. There is a higher incidence of chorea, also known as St.Vitus' Dance (abnormal sudden jerky movements).

Secondary APS Antiphospholipid Syndrome (Hughes' syndrome) patients may report symptoms of the underlying disease. For example, patients with underlying systemic lupus erythematosus may report features including a rash on the cheeks, skin reaction to sunlight, joint pains, mouth ulcers, excessive hair loss, dry eyes, cold and bluish fingers, and sometimes sharp chest pains.

Doctors will ask about clotting problems in the past (any history of clots in the leg or lung), previous strokes or heart attacks (and whether they occurred at young ages), less specific clues such as headaches, migraine, memory loss, and confusion. Women will be questioned about past pregnancies, and whether there were any complications. They will be asked specifically about any miscarriages, and at what stage of pregnancy they occurred.

A lacy, net-like, red rash known as 'livedo reticular is', is often found in antiphospholipid syndrome, particularly over the wrists and knees.

A simple blood test can detect the 'antiphospholipid antibodies'. Other blood tests can check for underlying conditions, such as systemic lupus erythematosus.