Overview
Congenital high-molecular-weight kininogen deficiency, also known as Fitzgerald factor deficiency, Williams trait, or Flaujeac trait, is a very rare inherited blood disorder. It affects a protein in the blood called high-molecular-weight kininogen (HMWK or HK), which plays a role in the contact activation pathway — a part of the blood clotting system. When this protein is missing or not working properly, certain laboratory clotting tests come back abnormal, which can be alarming at first. Despite the abnormal lab results, most people with this condition do not actually experience unusual bleeding in everyday life. This is one of the most important things to understand: the deficiency shows up strongly in a test called the aPTT (activated partial thromboplastin time), making it look like there is a serious clotting problem, but in reality the body usually clots normally during surgery, injury, or childbirth. This is because HMWK is not essential for the body's main clotting response in real-life situations. Because this condition is so rare and causes no real bleeding symptoms, it is most often discovered by accident — for example, when routine pre-surgical blood tests come back abnormal. Treatment is generally not needed. The main challenge is making sure doctors recognize this harmless condition so that patients are not given unnecessary treatments or denied needed procedures out of concern for bleeding risk.
Key symptoms:
No bleeding symptoms in most casesAbnormal result on a routine blood clotting test (aPTT) found by accidentPossible mild issues with blood vessel function in very rare casesNo increased risk of bruising in daily lifeNo increased bleeding during surgery or childbirth in most reported cases
Autosomal recessive
Passed on when both parents carry the same gene change; often skips generations
Variable
Can begin at different ages, from infancy through adulthood
Treatments
No FDA-approved treatments are currently listed for Congenital high-molecular-weight kininogen deficiency.
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Specialists
View all specialists →No specialists are currently listed for Congenital high-molecular-weight kininogen deficiency.
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 Congenital high-molecular-weight kininogen deficiency.
Community
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Caregiver Resources
NORD Caregiver Resources
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Mental Health Support
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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.Does my abnormal clotting test mean I am at risk for serious bleeding during surgery or injury?,Do I need any treatment, or is it safe to leave this condition untreated?,Should my family members be tested for this condition?,What should I tell surgeons or dentists before a procedure?,Should I carry any medical documentation or alert card about my diagnosis?,Are there any activities or medications I should avoid?,Is there a specialist or center with experience in rare clotting disorders I should see?
Common questions about Congenital high-molecular-weight kininogen deficiency
What is Congenital high-molecular-weight kininogen deficiency?
Congenital high-molecular-weight kininogen deficiency, also known as Fitzgerald factor deficiency, Williams trait, or Flaujeac trait, is a very rare inherited blood disorder. It affects a protein in the blood called high-molecular-weight kininogen (HMWK or HK), which plays a role in the contact activation pathway — a part of the blood clotting system. When this protein is missing or not working properly, certain laboratory clotting tests come back abnormal, which can be alarming at first. Despite the abnormal lab results, most people with this condition do not actually experience unusual blee
How is Congenital high-molecular-weight kininogen deficiency inherited?
Congenital high-molecular-weight kininogen deficiency follows a autosomal recessive inheritance pattern. Genetic counseling can help families understand recurrence risk and testing options.