Hemophilia
HemophiliaIn the human body, each cell contains 23 pairs of chromosomes, one of each pair inherited through the egg from the mother, and the other inherited through the sperm of the father. Of these chromosomes, those that determine sex are X and Y. Females have XX and males have XY. In addition to the information on sex, 'the X chromosomes carry determinants for a number of other features of the body including the levels of factor VIII and factor IX.'1 If the genetic information determining the factor VIII and IX level is defective, haemophilia results. When this happens, the protein factors needed for normal blood clotting are effected. In males, the single X chromosome that is effected cannot compensate for the lack, and hence will show the defect. In females, however, only one of the two chromosomes will be abnormal. (unless she is unlucky enough to inherit haemophilia from both sides of the family, which is rare.)2 The other chromosome is likely to be normal and she can therefore compensate for this defect. There are two types of haemophilia, haemophilia A and B. Haemophilia A is a hereditary disorder in which bleeding is due to deficiency of the coagulation factor VIII (VIII:C)3. In most of the
cases, this coagulant protein is reduced but in a rare amount of
cases, this protein is present by immunoassay but defective.4
Haemophilia A is the most common severe bleeding disorder and
approximately 1 in 10,000 males is effected. The most common types
of bleeding are into the joints and muscles. Haemophilia is severe
if the factor VIII:C levels are less that 1 %, they are moderate if
the levels are 1-5% and they are mild if they levels become 5+%.5
(2)
Those with mild haemophilia bleed only in response to major trauma
or surgery. As for the patients with severe haemophilia, they can
bleed in response to relatively mild trauma and will bleed
spontaneously.
In haemophiliacs, the levels of the factor VIII:C are reduced.
If the plasma from a haemophiliac person mixes with that of a
normal person, the Partial thromboplastin time (PTT) should become
normal. Failure of the PTT to become normal is automatically
diagnostic of the presence of a factor VIII inhibitor. The standard
treatment of the haemophiliacs is primarily the infusion of factor
VIII concentrates, now heat-treated to reduce the chances of
transmission of AIDS.6 In the case of minor bleeding, the factor
VIII:C levels should only be raised to 25% with one infusion. For
moderate bleeding, 'it is adequate to raise the level initially to
50% and maintain the level at greater that 25% with repeated
infusion for 2-3 days. When major surgery is to be performed, one
raises the factor VIII:C level to 100% and then maintains the
factor level at greater than 50% continuously for 10-14 days.'7
Haemophilia B, the other type of haemophilia, is a result of
the deficiency of the coagulation factor IX - also known as
Christmas disease. This sex-linked disease is caused by...
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