What is a Violation of Coagulation Hemostasis?
This group includes genetically determined hypocoagulations, characterized by a deficiency, as well as molecular abnormalities of blood coagulation factors.
Thus, 83-90% of all hereditary bleeding disorders are 2 types of factor VTII deficiency hemophilia A (70-78%) and von Willebrand disease (9-18%); another 6–13% are associated with factor IX deficiency (hemophilia B). Thus, the deficit of only two coagulation factors – VIII and IX – accounts for about 96–98% of all hereditary coagulopathies. The deficit of factors VII and V is recorded in 0.5-1.5%, factor X – in 0.3-0.5% of cases.
Not all violations in the blood coagulation system are accompanied by bleeding: it may be absent or be mild.
Hemophilia A. This disease is the most common coagulopathy, which is based on a deficiency of factor VIII (antihemophilic globulin), and is the only among them with a recessive X-chromosomal inheritance.
The variety of forms of the pathology of factor VIII reflects the complexity of its structure. In the blood, factor VIII circulates in the form of a protein complex consisting of a number of similar subunits.
Inheritance. The hemophilia gene, located in the X chromosome, is inherited from a sick man by all his daughters, who later inevitably carry the disease, while the patient’s sons remain healthy (due to the fact that they get the X chromosome from a healthy mother).
It should also be noted that a female carrier of hemophilia has the opportunity in 50% of cases to give birth to a healthy son, and half of the daughters become carriers of the hemophilia gene.
Women carriers, as a rule, do not suffer from bleeding, since the second normal X chromosome provides for the synthesis of factor VIII, which in most cases is sufficient to ensure hemostasis.
However, the rate of factor VIII varies in very large limits (60-250%). In this regard, in some transmitters, the level of factor VIII in plasma can be 11–20%, which creates a risk of bleeding from injuries, operations and childbirth. The doctor should remember about this danger during surgical interventions in mothers, sisters and especially daughters of patients with hemophilia. Before surgery and before childbirth, they should check the level of factor VIII in the plasma and, at rates below 25%, prophylactically administer cryoprecipitate at 7-10 U / kg per day.
Detection of the hemophilia gene carrier is facilitated by a detailed study of the familial hemorrhagic history in all the maternal blood relatives of the patient.
Hereditary genesis is established in hemophilia A in 70–75% of cases, and in hemophilia B, in 90–91%. The hemophilia A gene undoubtedly often mutates, since the number of patients has not diminished over many centuries, although until recently a significant portion of them died before reaching the childbearing age, which led to the natural decline of abnormal X chromosomes.