Haemophilia is an inherited condition that affects the blood’s ability to clot.
Haemophilia A (clotting factor VIII deficiency) is the most common form of the disorder, present in about 1 in 5,000–10,000 births.
Haemophilia B (factor IX deficiency) occurs in around 1 in about 20,000–34,000 births. Haemophilia is more likely to occur in males than females. This is due to the fact that females have two X chromosomes while males have only one, so the defective gene is guaranteed to manifest in any male who carries it. As females have two X chromosomes, the chance of a female having two defective copies of the gene is very rare, so females are almost asymptomatic carriers of the disorder.
Haemophilia lowers clotting factor levels of the coagulation required for a normal clotting process. Thus when a blood vessel is injured, a temporary scab does form, but the missing coagulation factors prevent fibrin formation, which is necessary to maintain the blood clot. Hemophiliac does not bleed more intensely than a person without it, but can bleed for a much longer time. In severe hemophiliacs even a minor injury can cause lot of blood loss which can last for days or weeks, or even never healing completely. In areas such as the brain or inside joints, this can be fatal or permanently debilitating.
The severity of the condition is determined by the level of clotting factors in the blood:
Mild hemophilia – someone has 5 to 50% of the normal amount of clotting factors
Moderate hemophilia – someone has 1 to 5% of the normal amount of clotting factors
Severe hemophilia – someone has less than 1% of the normal amount of clotting factors.
Mild hemophilia: Patient suffering may not have the symptoms but sometimes the condition becomes apparent after a significant wound or surgery. These events could cause unusually prolonged bleeding.
Moderate hemophilia: Patient with moderate hemophilia bruise easily. They may also have symptoms of internal bleeding around their joints, especially if they have a knock or a fall that affects their joints. This is known as a joint bleed. The symptoms usually begin with a feeling of irritation and mild pain in the affected joint. Most common involved areas are ankle joints, knee joints and elbow joints. Less commonly, the shoulder and hip joints can also be affected. If a joint bleed remains untreated, it can lead to:
More severe joint pain
The site of the bleed becoming hot, swollen and tender
Severe hemophilia: People with severe hemophilia can develop:
Joint deformity, which may require replacement surgery
Soft tissue bleeding, which could lead to further complications
Serious internal bleeding
Genetics: The genes are responsible for clotting factors VIII and IX are on the (X) chromosome. Females have two X chromosomes (XX) and males have one X chromosome and one Y chromosome (XY). If a female inherits an X chromosome with ‘hemophilia’ clotting factor genes, the other X chromosome will usually be normal, so they are still able to produce safe levels of clotting factors. Although some female ‘carriers’ of the ‘hemophilia’ X chromosome do have occasional clotting problems, they are rarely as serious as the problems in males. If a male inherits a ‘hemophilia’ X chromosome and they will not be able to produce normal levels of the clotting factors they need. Most males who inherit the ‘hemophilia’ X chromosome will have clotting problems some will be extremely severe.
Several options are available to diagnose hemophilia before, during and after birth if there is a family history of the condition.
Tests before pregnancy: Genetic testing and counseling.
Tests during pregnancy: Chorionic villus sampling (CVS) It is a procedure in which a small sample of placenta is removed from the womb and tested for the hemophilia gene, usually during weeks 10 to 13 of pregnancy
Amniocentesis: In this amniotic fluid is taken for testing, usually during weeks 15 to 20 or pregnancy
Tests after birth: If a child is suspected with hemophilia, a blood test can usually confirm the diagnosis. The blood test will also be able to identify whether child has hemophilia A or B.
As such there is no cure for hemophilia, it can be managed with regular infusions of the deficient clotting factor, i.e. factor VIII in hemophilia A or factor IX in hemophilia B. Factor replacement can either be isolated from human blood serum or a combination of the two. Some hemophiliacs develop antibodies (inhibitors) against the replacement factors given to them, so the amount of the factor has to be increased or non-human replacement products must be given, such as porcine factor VIII.
Gene therapy: On 10 December 2011, a team of British and American investigators reported the successful treatment of hemophilia B using gene therapy. They inserted the F9 gene into an adeno-associated virus-8 vector, which has a propensity for the liver, where factor 9 is produced, and remains outside the chromosomes so as not to disrupt other genes. The transduced virus was infused intravenously. To prevent rejection, the patients were primed with steroids to suppress their immune response.
Immune tolerance therapy (ITT): People with moderate to severe inhibitors are usually advised to try a treatment called immune tolerance therapy (ITT). ITT involves receiving daily injections of either octocog alfa (for hemophilia A) or nonacog alfa (for hemophilia B). ITT is carried out on a long-term basis, with most people needing a course of treatment that lasts 6–24 months.
Joint damage: Joint damage can sometimes develop if hemophilia is poorly controlled. Successive joint bleeds can damage cartilage (the soft spongy tissue in joints that acts as a shock absorber) as well as the synovium (a thin layer of tissue that lines the inside of the joint). The more damaged a joint is, the more vulnerable it is to internal bleeding. This in turn means the joint will become even more damaged and vulnerable to bleeding. Joint damage is more common in older adults with severe hemophilia. Surgery can be used to treat joint damage. If the synovium is damaged, it can be removed so new synovium can grow in its place. If a joint is seriously damaged, it may be necessary to replace the whole joint with an artificial one, such as a hip replacement or knee replacement.
Centre of Disease Control and Prevention