Overview
Antiphospholipid syndrome (APS), also known as Hughes syndrome or antiphospholipid antibody syndrome, is an autoimmune condition where the body's immune system mistakenly produces antibodies that attack certain proteins in the blood. These antibodies, called antiphospholipid antibodies, make the blood more likely to clot than normal. This can lead to dangerous blood clots forming in veins or arteries throughout the body, including the legs, lungs, brain, and kidneys. APS is one of the most common causes of recurrent miscarriages and pregnancy complications, as blood clots can form in the placenta and affect the baby's growth. People with APS may experience deep vein thrombosis (blood clots in the legs), strokes, heart attacks, or pulmonary embolism (blood clots in the lungs). Some people also develop a low platelet count, skin rashes, or heart valve problems. APS can occur on its own (primary APS) or alongside another autoimmune disease, most commonly systemic lupus erythematosus (secondary APS). In rare cases, a severe form called catastrophic antiphospholipid syndrome (CAPS) can develop, where multiple organ systems are affected at once. Treatment focuses on preventing blood clots using blood-thinning medications such as warfarin, heparin, and low-dose aspirin. With proper treatment, many people with APS can lead full and active lives, though lifelong monitoring and medication are usually necessary.
Also known as:
Key symptoms:
Blood clots in the legs (deep vein thrombosis)Blood clots in the lungs (pulmonary embolism)Stroke or mini-stroke (transient ischemic attack)Recurrent miscarriages or pregnancy lossLow platelet count causing easy bruisingSkin rash with a net-like purple pattern (livedo reticularis)Heart valve problemsKidney problemsHeadaches or migrainesMemory problems or difficulty concentratingLeg swelling and painPreeclampsia or premature birth during pregnancySkin ulcersVision changesFatigue
Clinical phenotype terms (39)— hover any for plain English
Multifactorial
Caused by a mix of several genes and environmental factors
Adult
Begins in adulthood (age 18 or older)
FDA & Trial Timeline
10 eventsInfanta Leonor University Hospital
New Valley University
CHU de Reims — NA
Central Hospital, Nancy, France
Central Hospital, Nancy, France
Assiut University
Centre Hospitalier Universitaire, Amiens — NA
Chugai Pharmaceutical — PHASE1
Peking University People's Hospital — PHASE2
Italian Society for Rheumatology
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for Antiphospholipid syndrome.
20 clinical trialsare actively recruiting — trials can provide access to cutting-edge therapies.
View clinical trials →Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to Antiphospholipid syndrome.
Community
No community posts yet. Be the first to share your experience with Antiphospholipid syndrome.
Start the conversation →Latest news about Antiphospholipid syndrome
Disease timeline:
New recruiting trial: Safety and Efficacy of Zanubrutinib in the Treatment of Antiphospholipid Syndrome With Secondary Thrombocytopenia
A new clinical trial is recruiting patients for Antiphospholipid syndrome
New recruiting trial: Anti-CD38 Antibody Treating APS With Thrombocytopenia
A new clinical trial is recruiting patients for Antiphospholipid syndrome
New recruiting trial: Laboratory and Clinical Data in Antiphospholipid Patients
A new clinical trial is recruiting patients for Antiphospholipid syndrome
New recruiting trial: Negative Antiphospholipid Syndrome: a Multicentric Study
A new clinical trial is recruiting patients for Antiphospholipid syndrome
New recruiting trial: Evaluation of Cell Membrane Expression of Annexin A2 on Monocytes by Flow Cytometry in Primary Antiphospholipid Syndrome
A new clinical trial is recruiting patients for Antiphospholipid syndrome
New recruiting trial: Genetic Risk Factors Associated With Antiphospholipid Antibody Syndrome
A new clinical trial is recruiting patients for Antiphospholipid syndrome
New recruiting trial: Chinese AntiphosPholipid Syndrome cohorT cOllaborative NEtworks
A new clinical trial is recruiting patients for Antiphospholipid syndrome
New recruiting trial: Register for Pediatric Patients With Antiphospholipid Syndrome (APS): European Project Extended Internationally Study
A new clinical trial is recruiting patients for Antiphospholipid syndrome
New recruiting trial: Prevalence and Consequences of Antiphospholipid Syndrome in Patients Aged 65 and Over With Ischemic Strokes (IS)
A new clinical trial is recruiting patients for Antiphospholipid syndrome
New recruiting trial: Antiphospholipid Syndrome and Postpartum Pulmonary Artery Pressure
A new clinical trial is recruiting patients for Antiphospholipid syndrome
Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.What type of antiphospholipid antibodies do I have, and does that affect my risk level?,How long will I need to take blood-thinning medication — is it lifelong?,What are the warning signs of a blood clot or bleeding emergency that I should watch for?,Is it safe for me to become pregnant, and what special care would I need during pregnancy?,Are there any medications, foods, or activities I should avoid while on blood thinners?,Should I be tested for lupus or other autoimmune conditions?,How often do I need blood tests and follow-up appointments?
Common questions about Antiphospholipid syndrome
What is Antiphospholipid syndrome?
Antiphospholipid syndrome (APS), also known as Hughes syndrome or antiphospholipid antibody syndrome, is an autoimmune condition where the body's immune system mistakenly produces antibodies that attack certain proteins in the blood. These antibodies, called antiphospholipid antibodies, make the blood more likely to clot than normal. This can lead to dangerous blood clots forming in veins or arteries throughout the body, including the legs, lungs, brain, and kidneys. APS is one of the most common causes of recurrent miscarriages and pregnancy complications, as blood clots can form in the plac
How is Antiphospholipid syndrome inherited?
Antiphospholipid syndrome follows a multifactorial inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
At what age does Antiphospholipid syndrome typically begin?
Typical onset of Antiphospholipid syndrome is adult. Age of onset can vary across affected individuals.
Are there clinical trials for Antiphospholipid syndrome?
Yes — 20 recruiting clinical trials are currently listed for Antiphospholipid syndrome on UniteRare. See the clinical trials section on this page for phase, sponsor, and site details sourced from ClinicalTrials.gov.
Which specialists treat Antiphospholipid syndrome?
25 specialists and care centers treating Antiphospholipid syndrome are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.