Antiphospholipid syndrome (APS), sometimes known as Hughes syndrome, is a disorder of the immune system that causes an increased risk of blood clots.

This means people withAPS are at greaterrisk of developing conditions such as:

  • deep vein thrombosis (DVT) , a blood clot that usually develops in the leg
  • arterial thrombosis (a clot in an artery), which can cause a stroke or heart attack
  • blood clots in the brain, leading to problems with balance, mobility, vision, speech and memory

Pregnant women with APS also have an increased risk of having a miscarriage , although the exact reasons for this are uncertain.

APS doesn't always cause noticeable problems, but some peoplehave general symptoms that can be similar to those of multiple sclerosis (a common condition affecting the central nervous system). This means the immune system, which usually protects the body from infection and illness, attacks healthy tissue by mistake.

In APS, the immune system produces abnormal antibodies called antiphospholipid antibodies. Thesetarget proteins attached to fat molecules (phospholipids), which makes the blood more likely to clot.

It's not known what causes the immune system to produce abnormal antibodies. As with other autoimmune conditions, genetic, hormonal and environmental factors are thought to play a part.

Therefore, blood tests to identify the antibodies responsible for APS are essential in diagnosing the condition.

These reduce the likelihood of unnecessary blood clots forming but still allow clots to form when you cut yourself.

Treatment with these medications can also improve a pregnant woman's chance of having a successful pregnancy. With treatment, it's estimated there's about an 80% chance of having a successful pregnancy.

Most people respond well to treatment and can lead normal, healthy lives. However, a small number of people with APS continue to experience blood clots despite extensive treatment.

CAPS requires immediate emergency treatment in hospital with high-dose anticoagulants .

Readmore about catastrophic antiphospholipid syndrome (CAPS) .

Information about you

If you have APS, your clinical team will pass information about you on to the National Congenital Anomaly and Rare Diseases Registration Service (NCARDRS).

This helps scientists look for better ways to prevent and treat this condition. You can opt out of the register at any time.

Find out more about the register .

Content supplied by the NHS Website

Medically Reviewed by a doctor on 29 Nov 2016