Sexualy Transmited Diseases: Hemophilia

Hemophilia is an inherited hemorrhagic disease that retards the blood clotting process in human blood. There are two kinds of diseases: hemophilia A and hemophilia B. Both cause very similar symptoms, but they are caused by different mutations of genes on the X chromosome. The way inheritance of this disease is called "X-linked recessive model". Since men have only one X chromosome, only one gene mutation can obtain hemophilia. On the other hand, women have two X chromosomes. In other words, two mutations (one for each X chromosome) are required to inherit haemophilia.

According to the National Hemophilia Foundation, the two main types of hemophilia are A and B. A is Factor VIII deficiency, Hemophilia B is Factor IX deficiency, and Hemophilia C is Factor XI deficiency. A woman inherits two XX chromosomes. One from mother and the other from her father (XX). Male inherits XY chromosome from father (XY). This means that if the son inherits the X chromosome from the mother of hemophilia, he will become haemophilia. However, since women accept two X chromosomes, only the parent with the defective gene will develop the disease.

Hemorrhagic Disease Haemophilia A is one of several monogenic diseases that exhibit a recessive inheritance pattern associated with the X chromosome. Men with mutated copies of Factor VIII gene (F8) are always haemophilic. In contrast, women have mutated genes in most cases, but it is rarely affected by this disease. Duchenne muscular dystrophy is another example of a single gene disorder showing X-linked recessive inheritance pattern. This condition is related to the mutation of the dystrophin gene (DMD)

Hemophilia A and hemophilia B are X-linked recessive genetic diseases caused by mutations in the genes encoded by linked factor VIII and factor IX. Both genes are on the X chromosome. Because men have only one X chromosome, hemophilia usually occurs in men. When the boy inherits a defective gene, it indicates a disease. In rare cases, there is a possibility of suffering from haemophilia by women (in cases where the father is a haemophilia patient and the mother is a carrier), or due to spontaneous mutation