Overview
Protein S acquired deficiency is a blood clotting disorder where the body does not have enough of a protein called Protein S. Protein S is a natural anticoagulant, meaning it helps keep blood from clotting too easily. When levels of Protein S are too low, blood clots can form in places they should not, which can be dangerous. Unlike inherited Protein S deficiency, the acquired form is not caused by a gene you were born with — instead, it develops during your lifetime due to other medical conditions or treatments. Common causes include liver disease, vitamin K deficiency, pregnancy, use of oral contraceptives or hormone therapy, certain autoimmune diseases like lupus, infections such as HIV, and some medications like warfarin or chemotherapy drugs. The main concern with this condition is an increased risk of developing abnormal blood clots, a condition called thrombosis. Clots can form in the deep veins of the legs (deep vein thrombosis or DVT) or travel to the lungs (pulmonary embolism), which is a medical emergency. Clots can also form in arteries, raising the risk of stroke or heart attack in some people. Treatment focuses on managing the underlying cause and preventing or treating blood clots. Blood thinners (anticoagulants) such as heparin, warfarin, or newer direct oral anticoagulants (DOACs) are commonly used. With proper treatment and monitoring, many people with acquired Protein S deficiency can manage their condition well and reduce their risk of serious complications.
Key symptoms:
Painful swelling in one leg (deep vein thrombosis)Redness and warmth in a swollen limbSudden shortness of breathChest pain, especially when breathing deeplyCoughing up bloodSudden weakness or numbness on one side of the body (possible stroke)Sudden difficulty speaking or understanding speechSevere headache with no known causeSkin discoloration or purplish patches (skin necrosis in rare cases)Repeated miscarriages in pregnancyFatigue related to underlying conditions causing the deficiency
Sporadic
Usually appears on its own, not inherited from a parent
Variable
Can begin at different ages, from infancy through adulthood
Treatments
No FDA-approved treatments are currently listed for Protein S acquired deficiency.
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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 Protein S acquired deficiency.
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Caregiver Resources
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Questions for your doctor
Bring these to your next appointment
- Q1.What is causing my Protein S deficiency, and can that underlying cause be treated?,Do I need to take blood thinners, and if so, for how long?,What are the signs of a blood clot I should watch for, and when should I go to the emergency room?,Are there activities or situations I should avoid because of my increased clotting risk?,If I want to become pregnant or am already pregnant, how does this condition affect my care?,Will my Protein S levels return to normal once the underlying cause is treated?,Should other members of my family be tested for clotting disorders?
Common questions about Protein S acquired deficiency
What is Protein S acquired deficiency?
Protein S acquired deficiency is a blood clotting disorder where the body does not have enough of a protein called Protein S. Protein S is a natural anticoagulant, meaning it helps keep blood from clotting too easily. When levels of Protein S are too low, blood clots can form in places they should not, which can be dangerous. Unlike inherited Protein S deficiency, the acquired form is not caused by a gene you were born with — instead, it develops during your lifetime due to other medical conditions or treatments. Common causes include liver disease, vitamin K deficiency, pregnancy, use of oral
How is Protein S acquired deficiency inherited?
Protein S acquired deficiency follows a sporadic inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.
Which specialists treat Protein S acquired deficiency?
1 specialists and care centers treating Protein S acquired deficiency are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.