Where's it located? The gene that causes hemophilia is located on the X Chromosome (National Hemophilia Foundation, 2006).
What's the cause? The F8 gene provides instructions for clotting for the Factor VII protein. However, in hemophilia A, this protein is damaged due to an inherited genetic mutation of the F8 gene, which therefore provides the wrong instructions to the Factor VII protein, making it unable to clot blood normally (U.S. National Library of Medicine, 2014).
What are the symptoms? People with hemophilia experience prolonged bleeding, excessive bruising, nose bleeds, etc. Surgery is also high risk for them, as some may suffer from extreme internal bleeding (Konkle, 2011).
Why are most women only carriers? Women carry XX chromosomes, whereas men inherit XY chromosomes. Because the gene is located on the X Chromosome, a woman would have to inherit the mutation on both of her X chromosomes for it to take affect. However, a man only has one X chromosome, so it's much more likely that they inherit the disease. Women are carriers because they may carry the gene on one of their X chromosomes and pass it on to their sons (National Institute of Health, 2013).
So if a mother is a carrier, will her son definitely have the disease? Not necessarily. Nothing is guaranteed 100% genetically, so a carrier's son may not have the disease, just as the daughter may not be a carrier. In fact, the hemophilia gene may be quietly passed down for generations without appearing (Hemophilia Federation of America, 2014).
Can environmental factors cause the disease? No. The disease is purely hereditary- stress is not a factor, and the disease doesn't affect moods (National Institute of Health, 2013).
Any perks? Not really. Unlike sickle cell anemia, which allows those infected to be resistant to malaria, there isn't a disease that those with hemophilia are particularly resistant to.
Who's affected? Everyone can be affected by hemophilia. The disease does not pertain to a specific ethnic group or social class. Only about 1 in 20,000 Americans are affected by the disease (U.S National Library of Medicine, 2014).
But it's just humans, right? Nope. Hemophilia also pops up in other organisms, such as dogs. The disease appears in dogs as a result of a spontaneous mutation. (Cornell, 2014).
When does the disease begin showing signs? Babies are usually diagnosed with hemophilia within one year of life. In addition, there are prenatal tests that can be performed. One is chorionic villus, performed during the 10th or 12th week of pregnancy. Another is amniocentesis, performed at about 13 weeks, in which part of the placenta is removed and tested for hemophilia if the unborn child is male (Cincinnati Children's Hospital, 2013).
What about hemophilia B? Hemophilia B is more rare than Hemophilia A, and is the result of a deficiency in another protein; while Hemophilia A is caused by low amounts of factor VIII, Hemophilia B is caused by low amounts of factor IX. Both diseases have similar symptoms (Hemophilia Federation of America, 2014).
