Synonyms: Severe congenital F9 deficiency | Severe congenital factor IX deficiency
A severe form of hemophilia B characterized by a large deficiency of factor IX (biological activity <1 IU/dL) leading to frequent spontaneous hemorrhage and abnormal bleeding as a result of minor injuries or following trauma surgery or tooth extraction. It primarily affects males but may also be observed in female carriers of disease-causing mutations.
Data from Orphanet are used to provide information on a disease's name, synonym(s), and overview. Reference: Access aggregated data from Orphanet at Orphadata. Orphadata: Free access data from Orphanet. © INSERM 1999. Available on http://www.orphadata.org. Data version April 2026
Newly diagnosed with
Severe hemophilia B?
Our RARE Concierge Services Guides are available to assist you by providing information, resources and connections as you navigate your rare disease journey.
Advocacy Organizations
Bleeding Disorders Alliance Illinois
The Bleeding Disorders Alliance Illinois exists to improve the quality of life for the inherited bleeding disorders community by supporting individuals and their families with unbiased information and resources which allows them to live healthy and active lives.
Bleeding Disorders Council of California
More than three decades after its founding, BDCC continues to pursue its mission to promote access to care and advance the quality of life for people with bleeding disorders. In collaboration with our founding organizations, BDCC continues to elicit change through advocacy, education, and outreach.
Hemophilia Foundation of Southern California
“Improving the quality of life and building community for those living with inherited bleeding disorders in Southern California.”
Hemostasis and Thrombosis Center of Nevada
The Hemostasis & Thrombosis Center of Nevada (HTCNV) is Nevada's only federally designated hemophilia treatment center (HTC). We provide care for benign inherited blood disorders specifically bleeding disorders, thrombotic disorders and sickle cell disease. Our mission is to provide access to compassion evidence based quality care to all patients in Nevada regardless of their ability to pay.
National Center of Hematology and Blood Transfusion
Treatment of patients with blood diseases,scientific-research works
National Hemophilia Foundation
The National Hemophilia Foundation (NHF) is dedicated to finding cures for inheritable blood disorders and to addressing and preventing the complications of these disorders through research, education, and advocacy enabling people and families to thrive.
New York City Hemophilia Chapter
NYCHC’s mission is to foster a sense of community amongst people affected by bleeding disorders in the greater NYC area, and to improve their health outcomes and quality of life
OPFORD Foundation
OPFORD.org (Open Platform for Rare Diseases) was conceived as a digital and online resource centre for orphan diseases with a primary focus of serving patients and caregivers by connecting them to curated resources regarding symptoms, causes, diagnosis and treatment. We have expanded our services to health counselling and guidance for patients and caregivers to prevent possible complications.
Save One Life, Inc
Empowering individuals and families affected by bleeding disorders in developing countries through direct financial assistance and access to medical treatment.
V_life savers foundation
Save the life of hemophilia patients and non hemophilia patients and bleeding disorder.
Wave of Support, Inc
Empowering those affected by bleeding disorders and other rare disease through advocacy, resources, education, and support
accessia health
Accessia Health, a national charitable patient assistance organization, is dedicated to eliminating healthcare barriers for people with rare or chronic health conditions. Comprehensive services include personalized case management, financial assistance, education, and legal aid support. Our flexible funding model goes beyond copays, allowing individuals to pay for other essential medical expenses
Don't see your organization here. Let us know here.
Clinical Trials
For a list of clinical trials in this disease area, please click here.