What is Haemophilia or von Willebrand’s
disease?
Definition
Haemophilia is a genetically inherited bleeding disorder where there
is a deficiency of a clotting factor in the blood. This results
in a form of bleeding tendency. Thus, the haemophilia patient often
suffers from easy bruising and bleeding into muscles and joints.
Because of the genetic pattern of inheritance, the disorder generally
affects males only. Females with the haemophilia genes are known
as carriers.
There are 2 types of haemophilia.
- Haemophilia A – Deficiency of clotting factor 8 (VIII)
- Haemophilia B – Deficiency of clotting factor 9 (IX)
There is another hereditary bleeding disorder known as von Willebrand’s
disease (vWD). A patient with vWD has a diminished production of
the von Willebrand clotting factor. In contrast with haemophilia,
vWD affects both males and females equally. They usually bleed from
the nose, mouth or intestinal tract.
Incidence
The incidence of haemophilia A is 1 in 10,000 males.
The incidence of haemophilia B is 1 in 50,000 males.
There is no known geographical variation in the incidence of haemophilia.
In the world, 350,000 people are estimated to be with severe or
moderate haemophilia A. In Singapore, about 200 people are patients
of haemophilia A and B.
Severity
The severity of the bleeding tendency depends on the range of activity
of factor 8 or 9.
|
Status |
Activity
Range |
Amount
of
Clotting Factor |
| Normal Person |
50 – 200% |
0.5 – 2 IU |
| Carrier |
25 – 49% |
0.25 – 0.49
IU |
| Haemophiliac |
Mild |
6 –25% |
0.06 – 0.25
IU |
| Moderate |
1 – 5% |
0.01 – 0.05
IU |
| Severe |
< 1% |
< 0.01 IU |
|
