A concise write-up on the causes of hemophilia which will shed some light on its pathogenesis, and its genetic transmission from one individual to another. Continue reading….
There are many such diseases in the world that are not caused by an external factor – like bacteria or viruses. Instead, these conditions are caused by genetic factors that are present in the body right from birth. These diseases are referred to as hereditary genetic diseases. One such disease that comes under the spectrum of hereditary genetic diseases is hemophilia – a condition wherein the body’s clotting or coagulation mechanism is impaired as a result of which bleeding does not stop after the stipulated period when there is an injury and a blood vessel is broken.
Causes of Hemophilia
When we wish to discuss the causes of this recessive genetic disorder, it will entail both – exactly what causes the symptoms of this condition and how this condition is passed on from one individual to another as hemophilia causes and symptoms are interrelated.
Pathogenesis of Hemophilia
There exist three different types of hemophilia, classified on the basis of the kind of clotting factor that is missing. They are:
- Hemophilia A or classic hemophilia: At 80 percent, this is the most common hemophilia type which is caused as a result of clotting factor VIII deficiency.
- Hemophilia B: If Hemophilia A constitutes 80 percent of the cases, Hemophilia B – caused by factor IX deficiency, constitutes nearly 20 percent of the cases.
- Hemophilia C: This is the rarest of all three and is caused due to deficiency of clotting factor XI. This is usually the mildest of all three.
In short, hemophilia is caused due to a missing clotting factor which is required for the normal coagulation process to be completed. When a blood vessel is broken, in case of a hemophilic, a small scab does form, but the fibrin formation – which leads to the hardening and closure of the wound, doesn’t occur. Due to this lack of formation of a basic blood clot, the bleeding will not be more intense – but instead may last much longer with blood occasionally oozing out for days or even weeks at times. That being said, such an injury could be fatal if it takes place inside the body – like in the brain or in the internal organs.
Transmission of Hemophilia
Since hemophilia is not caused due to any external microorganism, we should try and understand how this condition then manages to affect an individual. As mentioned earlier, it is a sex linked recessive disorder. We know that every human being has two chromosomes – XX chromosome pattern in females whereas XY pattern in males. The defective gene for hemophilia is present only on the X chromosome. Thus, if males manage to get that X chromosome which contains the defective gene, they will suffer from hemophilia this regressive genetic disorder.
This scenario is however different for females. When it comes to females, if a woman has one X chromosome which has the defective gene, then the healthy X chromosome will camouflage this gene, that is, the female with just one affected X chromosome will not show any symptoms despite having one chromosome for it. Thus, she will be what is known as a carrier of the hemophilic gene. In some very rare cases though, if both the X chromosomes of a female have the affected gene, then she will suffer from hemophilia.
The inheritance pattern of hemophilia is what is known as crisscross or cross linked. If a mother is a carrier, then there is 50 percent chance that the daughter will be a carrier and not a sufferer of hemophilia. However, if the mother is a carrier, then there is 50% chance that the son will also suffer from this disorder. Unless the father and mother both have the gene for hemophilia, this condition is passed on from the mother to the son and cannot be passed on from father to son, as the father will contribute the Y chromosome and not the defective X chromosome to his son. There are times when even males that do not have hemophilic carrier mothers may be born with hemophilia. This is seen when there is a random mutation in the gene, and this mutated gene is passed on from the mother to the son.
Hemophilia is such a condition that follows the same pattern as that seen in other cross linked hereditary conditions such as color blindness. Although the incidence of hemophilia is just 1 in every 5000 – 10,000 males, this condition needs to be taken seriously. As soon as this condition is diagnosed, one must make all attempts to understand the symptoms that surface and how to deal with them. Despite there being no cure for this disorder, one can easily monitor its symptoms and keep them in check by taking certain simple precautionary measures like regular checkups and regular infusions of the deficient clotting factors.
