The word hemophilia literally means "blood loving". Hemophilia is an inherited blood clotting disorder. That means you cannot CATCH it. Instead, females carry the gene which causes it and pass it to their offspring. Hemophilia occurs mainly in males. In someone with hemophilia, bleeding lasts longer than it would in someone without hemophilia. A person with hemophilia has prolonged bleeding because one of the clotting factors is defective or inactive. As a result, a strong clot does not form and bleeding continues. A person with hemophilia does not bleed faster than someone
without hemophilia. However, the person with hemophilia will bleed longer.

Hemophilia is classified as mild, moderate, or severe depending on the person's clotting factor activity level. Estimates indicate that approximately one in 10,000 males born in the US has hemophilia. All races and socio-economic groups are affected equally.

I talked to my sister about this question; she is studying to be a genetic counselor and will advise people on how to deal with this and many other genetic conditions.She's actually read quite a bit on this topic recently for a presentation to her classmates.

Hemophilia is caused by a genetic defect in which a protein necessary in the blood clotting process in not made by the body in sufficient quantities. It is a hereditary condition that is passed on by the mother through an X chromosome. Females have two X chromosomes and pass one of those on to their children; males have an X and a Y chromosome and give the X chromosome to any female child and the Y chromosome to any male child. If a woman should pass on to her male child an X chromosome with the hemophilia gene then her son will have hemophilia. It is much harder for women to get hemophilia because both X chromosomes would have to have the hemophilia gene (there are other ways for a women to get hemophilia but it is complicated and I'm not the right person to ask). I'd suggest finding out what chromosomes are if you aren't yet familiar with the term.

Hemophilia (hemo=blood, philia=liking or loving) is not a disease you "catch". It is a disease you are born with. Your blood is made of several things. One of those kinds of things is platelets. Platelets help your body to stop bleeding. Usually, when you are cut the platelets stick together to form a plug. They also put out a bunch of different chemicals to speed up healing. A person with hemophilia does not have the right genes (the recipes the body uses) to make the chemicals that help the blood clot.

We get our genes from our parents. Each parent gives us a set of recipes or instructions that we call genes. Each of our cells has a full set of these recipes. Sometimes a mutation makes a recipe "bad", so the body can't make what it's supposed to. If we still get a good recipe from the other parent, we do okay.

The genes (recipes) for blood clotting are on the X chromosome. Males are much more likely to have hemophilia (1 in 10,000 males) than females are. Why? (hint: what determines whether we'll be male or female?)

Thanks for asking.