What is Hemophilia?
People with hemophilia may bleed longer because blood does not clot as fast as it should. A person with this genetic disorder may have problems with profuse bleeding after an injury or may even bleed internally without knowing it
It’s the job of platelets and a group of proteins known as clotting factors to clot blood and seal a wound after an injury. However, people born with hemophilia have reduced levels of these clotting factors. They may even have no clotting factors at all.
According to the National Hemophilia Foundation there are two main types of hemophilia: hemophilia A, (low levels of clotting factor VIII) and hemophilia B (low levels of clotting factor IX). Hemophilia type A is the most prevalent cause of hemophilia (90%).
In the United States 18,000 people are affected by hemophilia. It has been estimated that every year 400 babies (usually males) are born with hemophilia.
Hemophilia: An X-linked Genetic Disorder
People who are born with hemophilia have an abnormality in one of the genes that codes for blood clotting factors VIII or IX. These genes, named KRO-muh-somz, are localized on the X chromosomes. Females have one pair of X chromosomes, while males have only one X (the other is a Y chromosome). Only the X chromosome has the genes that may cause hemophilia.
When a male has the abnormal gene on his X chromosome then he will be born with hemophilia. For a female to have hemophilia she would have to be born with both of her X chromosomes affected, which is very rare.
Females are usually “carriers” of the hemophilia disease. They may have the abnormal gene on one of their X chromosomes and could pass it on to the next generation.
Replacement therapy, that is replacing clotting factors (either factor 8 or 9) in a blood’s patient, is the main treatment for hemophilia patients. They’re either slowly dripped into the patient or injected. But it’s not without problems as some complications can occur. For example antibodies may develop against the clotting factors, there’s a possibility of viral infections and delayed treatment can lead to the damage to the joints and muscles.
Also, Desmopressin (DDAVP), a man-made hormone and antifibrinolytic medicines (tranexamic acid and aminocaproic acid) can be used in conjunction with replacement therapy.
Gene therapy for hemophilia?
Gene therapy for hemophilia is in its research phase. Because it’s a single gene disorder there’s the tantalising prospect that the bad gene can be easily replaced. However, though many trials have taken place, in dogs and in humans, there is still no effective therapy. Some places have reported modest success. In 2000 the Children’s Hospital of Philadelphia and Stanford University used gene therapy to help patients with hemophilia B. However, there were only 3 patients in the study. More trials are underway at present and the world watches closely to see what the outcome will be.
National Hemophilia Foundation www.hemophilia.org/