Hemophilia A
Hemophilia A is the most common type of
hemophilia. It is also known as factor
VIII deficiency or classic hemophilia. It
is largely an inherited disorder in which
one of the proteins needed to form blood
clots is missing or reduced. In about 30% of
cases, there is no family history of the
disorder and the condition is the result of
a spontaneous gene mutation.
Approximately one in 5,000 males born in the
United States has hemophilia. All races and
economic groups are affected equally.
When a person with hemophilia is injured, he
does not bleed harder or faster than a
person without hemophilia, he bleeds longer.
Small cuts or surface bruises are usually
not a problem, but more traumatic injuries
may result in serious problems and potential
disability (called "bleeding episodes").
There are different levels of hemophilia:
mild, moderate, and severe:
• People with mild hemophilia (6% to 49%
factor level) usually have problems with
bleeding only after serious injury, trauma,
or surgery. In many cases, mild hemophilia
is not discovered until an injury or surgery
or tooth extraction results in unusual
bleeding. The first episode may not occur
until adulthood.
• People with moderate hemophilia,
about 15% of the hemophilia population, tend
to have bleeding episodes after injuries.
They may also experience occasional bleeding
episodes without obvious cause. These are
called "spontaneous bleeding episodes."
• People with severe hemophilia,
about 60% of the hemophilia population, have
bleeding following an injury and may have
frequent spontaneous bleeding episodes,
often into the joints and muscles.
Everyone inherits two sex chromosomes, X and
Y, from his or her parents. A female
inherits one X chromosome from her mother
and one X chromosome from her father (XX). A
male inherits one X chromosome from his
mother and one Y chromosome from his father
(XY). The gene that causes hemophilia is
located on the X chromosome.
A woman who gives birth to a child with
hemophilia often has other male relatives
who also have hemophilia. Sometimes, a baby
will be born with hemophilia when there is
no known family history. This means either
that the gene has been "hidden" (that is,
passed down through several generations of
female carriers without affecting any male
members of the family) or the change in the
X chromosome is new (a "spontaneous
mutation").
There are four possible outcomes for the
baby of a woman who is a carrier. These four
possibilities are repeated for each and
every pregnancy:
1. A girl who is not a carrier
2. A girl who is a carrier
3. A boy without hemophilia
4. A boy with hemophilia
With each pregnancy, a woman who is a
carrier has a 25% chance of having a son
with hemophilia. Since the father's X
chromosome determines the baby will be a
girl, all the daughters of a man with
hemophilia will be carriers. None of his
sons, which is determined by the father
through his Y chromosome, will have
hemophilia.
Genetic counseling is available at most HTCs.
These professionals have information to help
you make family planning decisions.
In general, small cuts and scrapes are
treated with regular first-aid: clean the
cut, then apply pressure and a band-aid.
Individuals with mild hemophilia can use a
non-blood product called desmopressin
acetate (DDAVP) to treat small bleeds. Deep
cuts or internal bleeding, such as bleeding
into the joints or muscles, require more
complex treatment. The clotting factor
missing (VIII or IX) must be replaced so the
child can form a clot to stop the bleeding.
Some factor products are made from human
blood products such as donated plasma.
Others, called "recombinant factor," are
made in a laboratory and do not use human
blood products. The Medical and Scientific
Advisory Council of the National Hemophilia
Foundation encourages the use of recombinant
clotting factor products because they are
safer. Your doctor or your HTC will help you
decide which is right for you. All factor
treatments are injected or infused directly
into the veins.
In cases of severe hemophilia, doctors
sometimes recommend giving a regimen of
regular factor replacement treatments (a
therapy called prophylaxis) to prevent
bleeding episodes before they happen. The
Medical and Scientific Advisory Council of
the National Hemophilia Foundation
recommends prophylaxis as optimal therapy
for children with severe hemophilia A and B.
Notify your doctor or HTC if your child does
not respond to the usual dose of factor. In
rare instances, people can develop an
inhibitor, to standard factor treatment. In
the event this occurs, your doctor or HTC
will work with you to develop a special plan
of care.
