Christina Di Bernardo & Jennifer Lundberg

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Where on Chromosome is Problem?


Haemophilia (also hemophilia) is an X-linked recessive trait, and is thus located on the X chromosome. The X chromosome has the gene responsible for the production of factors VIII and IX (clotting factors), which is why haemophilia is an X-linked trait, since this disorder causes a deficiency in these clotting factors. There are two different types of haemophilia: haemophilia A is a deficiency of factor VIII, and is five times more common than haemophilia B; haemophilia B is a deficiency of factor IX, and often there is no family history for this type. Because haemophilia is an X-linked recessive trait, males are more likely to have this disorder, since they have only one X chromosome. Females would need to have the disorder on BOTH X chromosomes, and because this is usually not seen, most females are just carriers of the disorder (if they have the disorder at all).

Click here to see some genetic trait charts.

What Is the Problem?


Haemophilia is a bleeding disorder that slows the blood clotting process. People with this condition have prolonged bleeding and cannot easily stem the flow. In cases of haemophilia, excessive bleeding will occur after an injury (or also surgery, having a tooth pulled, etc.) has been sustained. In severe cases, bleeding can be caused by minor trauma or can even occur spontaneously. Bleeding can also occur in the joints, muscles, brain, or other internal organs. Basically, you just won’t stop bleeding without medical help.

What is the Prognosis?


Someone with haemophilia can expect to have anything from easy bruising to prolonged bleeding. Mobility problems may also arise. How badly a person bleeds depends on the severity of their deficiency. Minor cuts don’t usually cause severe problems, but internal bleeding can be life threatening and bleeding into the joints can cause arthritis or long-term joint damage. Haemorrhages into the brain are difficult to handle and can be fatal. There is currently no cure for haemophilia, but people with this disorder can expect to lead normal lives. Life expectancy depends on whether the person receives proper medical care or not. Without proper treatment, most people with haemophilia die before adulthood. With proper treatment however, the life expectancy of a person with haemophilia is about 10 years less than that of males without the disorder.

Cite Your Sources


BBC - Health: Haemophilia

Hemophilia and Genetics

Genetics Home Reference

World Federation of Hemophilia: Frequently Asked Questions