Hemophilia is a sex-linked disease, which is characterized by a condition of clotting factor deficiency of the intrinsic or plasma pathway of the coagulation cascade. The most commonly occurring hemophilias are hemophilia A and hemophilia B, resulting from a deficiency in the coagulation factor VIII and factor IX, respectively. Both of these hemophilias are associated with the sex chromosome X; hence males usually get affected while the females are the carriers of hemophilia trait. With each pregnancy, a female who is acting as a carrier of hemophilia has a 25% chance of having a son with this disease. Since all daughters inherit X chromosome from their fathers, all the daughters of a man with hemophilia will be carriers. Hemophilia affects the secondary homeostatis. The factors VIII and IX are vital for the activation of factor X, followed by thrombin generation. Thrombin, in turn, leads to the coagulation of blood by forming fibrin. When injury occurs in an individual with hemophilia, since the platelet function is normal, a platelet plug will be formed. But due to the lack of fibrin formation, the plug will not be able to stabilize; hence it leads to continuous bleed via the injury. The diagnosis is basically done by inspecting the family history of the affected individual. Since hemophilia is a sex-linked disease, there are no cures for it. The only treatment is to supply deficient factor at increasing concentrations to those who are affected.
Hemophilia A
This is the most common type of hemophilia that can occur in one in 10,000 male live births, in the general population. This disease occurs due to the deficiency of coagulation factor VIII. Most symptomatic patients have this factor level less than 5%. The severity of hemophilia A is categorized as mild, moderate, and severe. Normally patients with factor level less than 1% are considered as having severe hemophilia. Patients with factor level greater than 5% are considered as having mild hemophilia, and those with factor level range of 1% to 5% are considered to have moderate hemophilia.
Hemophilia B
Among the other hemophilias, hemophilia B is the second most common hemophilia that occurs due the deficiency of factor IX. Hemophilia B is also called ‘Christmas disease’. This disease was first diagnosed in 1952. Normal plasma has the factor IX level range from 50% to 150%. Depending on the level of the factor, the severity of hemophilia can be categorized as mild, moderate, and severe. The levels of factors that are used to determine the severity are similar to that of hemophilia A.
What is the difference between Hemophilia A and B?
• Hemophilia B is less common than Hemophilia A.
• When consider the general population, Hemophilia B affects approximately one in 50,000 people while, Hemophilia A affects fewer than one in 10,000 people.
• Hemophilia A occurs due to the deficiency of factor VIII, whereas Hemophilia B occurs due to the deficiency of factor IX.