Haemophilia B

Baby Detect > Haematology > Haemophilia B

F9 gene

OMIM#306900 https://omim.org/entry/306900

Also known as: Factor IX deficiency

1. The disease:

A rare hematological disorder characterized by spontaneous or prolonged hemorrhages due to factor IX deficiency.

2. The symptoms:

In general, onset of bleeding anomalies occurs when affected babies start to learn to walk. Bleeding most often occurs in joints (hemarthroses) and muscles (hematomas), but any site may be involved following trauma or injury. Spontaneous haematuria is a frequent and highly characteristic sign of the disorder. However, newborns with haemophilia are at risk of intra- or extracranial haemorrhage and other bleeding complications. Lack of early signs or symptoms does not exclude the diagnosis.  

  • The severity of clinical manifestations depends on the extent of factor IX deficiency in both males and females (in rare abnormal cases).
  • If the biological activity of factor IX is below 1 IU/dL, haemophilia is severe and manifests as frequent spontaneous haemorrhages and abnormal bleeding because of minor injuries or following trauma, surgery or tooth extraction (severe haemophilia B).
  • If the biological activity of factor IX is between 1 and 5 IU/dL, haemophilia is moderately severe with abnormal bleeding because of minor injuries or following trauma, surgery or tooth extraction but spontaneous haemorrhage is rare (moderately severe haemophilia B).
  • If the biological activity of factor IX is between 5 and 40 IU/dL, haemophilia is mild with abnormal bleeding because of minor injuries or following trauma, surgery or tooth extraction but spontaneous haemorrhage does not occur (mild haemophilia B).

3. Actions to take in case of early diagnosis:

  • Correlation with other exams as prolonged coagulation times (activated partial thromboplastin time, aPTT), measuring factor IX activity and antigen levels.
  • Haemophilia is a lifelong disease requiring lifetime management and regular follow-up with a Haematology Center.  Management is provided by multidisciplinary comprehensive haemophilia care centers.
  • Replacement therapy consisting of administration of the missing factor IX is the most straight forward treatment approach, using plasma-derived or recombinant factor IX concentrates. Treatment may be administered after a haemorrhage or prophylactically, to prevent bleeding. The most frequent complication is the production of inhibitory antibodies against the administered coagulation factor.
  • Agents/circumstances to avoid: Circumcision of at-risk males until hemophilia B is either excluded or treated with factor IX concentrate regardless of severity; intramuscular injections; activities with a high risk of trauma, particularly head injury; aspirin and all aspirin-containing products. Cautious use of other medications and herbal remedies that affect platelet function.
  • Clinical trials of additional longer-acting recombinant factor IX concentrates and gene therapy using intravenous infusion of an adeno-associated viral vector expressing factor IX are underway.
  • Surgical interventions, most notably orthopaedic surgery, may be carried out but should be conducted in specialized centers.
  • The pattern of inheritance is X-linked and genetic counselling should be offered to at-risk family members.

4. For more information:

Orphanet : https://www.orpha.net/consor/cgi-bin/Disease_Search.php?lng=EN&data_id=13896&Disease_Disease_Search_diseaseGroup=hemophilia-B&Disease_Disease_Search_diseaseType=Pat&Disease(s)/group%20of%20diseases=Hemophilia-B&title=Hemophilia%20B&search=Disease_Search_Simple

Biblio : https://www.ncbi.nlm.nih.gov/books/NBK1495/