What is hemophilia?
Hemophilia is a hereditary disorder in
which one of the proteins that causes
blood
to clot is missing, reduced or does
not function adequately, which leads to
a delay or disruption in blood clotting
and results in prolonged bleeding.
Types of hemophilia
The two most common types of hemophilia
are Factor VIII and Factor IX Deficiency.
Factor VIII Deficiency also is called
classic hemophilia or hemophilia A. Factor
IX Deficiency is often known as Christmas
disease or hemophilia B. Hemophilia occurs
in about one of every 5,000 males born
in the United States. About 80 percent
of persons with hemophilia have Factor
VIII Deficiency. Blood tests are needed
to tell the difference in types of hemophilia
as the bleeding patterns, signs and symptoms
are identical. However, the type of treatment
to stop bleeding depends upon the type
of hemophilia.
Causes
of hemophilia
The first two steps in clotting work
normally for persons with hemophilia.
However, persons with hemophilia do not
have enough of one of the clotting factors
needed to make fibrin strands. Without
the fibrin strands, a firm clot does not
form. Bleeding will only temporarily stop
since the clot easily dissolves.
Genetics
of hemophilia
The gene that causes hemophilia is carried
on the X chromosome (one in the pair of
chromosomes that determines sex). The
hemophilia gene is therefore called "sex-linked."
The hemophilia gene also is "recessive,"
which means that if the other chromosome
in the pair is normal X chromosome, the
normal chromosome "dominates"
over the recessive, hiding this trait.
Therefore, since females have two X chromosomes,
they would have to have two hemophilic
X chromosomes to have the disease. Males,
on the other hand, have only one X chromosome.
If a male’s X chromosome has the
abnormal factor gene, he will automatically
have hemophilia.
Severity
and symptoms
Persons with hemophilia do not bleed
any faster than persons without a bleeding
disorder. Generally external bleeding
(cuts, scrapes) does not cause any problems.
In children, bleeding is closely related
to the stages of development and to physical
activity. For babies and toddlers, the
most common sites of bleeding are the
mouth and head. Older children and adults
often have bleeding into joints and muscles,
especially the knees, ankles and elbows.
While the most common bleeding in hemophilia
is not life threatening, bleeding in a
few places of the body is very dangerous.
Examples of life-threatening bleeds are
bleeds into the head, neck, spinal cord
or stomach/intestines.
How is the severity of hemophilia
determined?
The table below shows the relationship
of mild, moderate and severe hemophilia
to the amount of clotting factors VIII
or IX.
| |
Levels of
Severity |
|
|
Factor
VIII or IX level |
Classification
|
What
to expect |
|
Less
than 1% |
Severe
hemophilia |
Bleeding
after minor injury; may bleed "spontaneously"
(without known injury) |
|
1
– 5% |
Moderate
hemophilia |
Bleeding
after minor injury is possible;
may have spontaneous bleeding |
|
5
– 30% |
Mild
hemophilia |
Usually
prolonged bleeding only after minor
trauma or surgery |
|
50
– 150% |
Normal
|
No
abnormal bleeding |
Treatment
There is no cure for hemophilia at this
time. The current treatment is to replace
the missing clotting factor in the blood
by injecting intravenously (into a vein)
products containing concentrated amounts
of the missing clotting factor. Clotting
factor is now given "prophylactically"
to prevent bleeding.
Can hemophilia ever
be cured?
Several centers throughout the country
currently are working on research to modify
genes in humans to allow them to make
clotting factors. This work is very promising.
The CVCCD is part of a national network
of treatment centers so our patients often
have access to new clinical trials.
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