Hemophilia Essay Research Paper 1

Hemophilia Essay, Research Paper

(1)

In 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

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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 the reduced

amount of the factor IX. Unlike haemophilia A, the percentage of

it’s occupance due to an abnormally functioning molecule is larger.

The factor IX deficiency is 1/7 as common as factor VIII deficiency

and it is managed with factor VIII concentrates. Unlike factor VIII

concentrates which have a half-life of 12 hours, the half-life of

factor IX concentrates is 18 hours. In addition, factor IX