Hemophilia is a genetic disorder passed from one generation to the next through the X (female) chromosome. It is a disease in which the blood does not clot normally, due to abnormalities in some blood proteins that cause clotting. People with hemophilia (hemophiliacs) have blood that clots very slowly. They are in constant danger of bleeding to death, even if they have a minor injury. Surgery or even dental work can also be very risky. Although women transmit the disease, only men can exhibit it. Women who carry hemophilia (carriers) have the gene on one of their X chromosomes. Since the gene is recessive, they do not have the disorder. But if a male has the bad gene, then he will be a hemophiliac because there is no matching gene on his Y chromosome to be dominant to it. Females must have the gene on both X chromosomes to have hemophilia. In the past, most hemophiliacs died young, but today, they can be treated with blood transfusions. The following is a chart of the hemophilia trait in one family over two generations.
| Hemophilia is often called the disease of kings
because it was carried by many members of Europe’s royal family. Queen Victoria of
England was a carrier of hemophilia and passed the disease to many of her descendants
(including the Russian emperor’s family and the Spanish royal family). Many people
say that this played a small role in the downfall of the Russian royal family during the
Russian Revolution.
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HEMOPHILIA | CYSTIC FIBROSIS | HUNTINGTON'S DISEASE | SICKLE-CELL ANEMIA | CANCER | QUIZ
England's
Royal Family