http://www.sina.com.cn 2008年01月22日 14:05
Hemophilia is a condition in which the blood either clots slowly or fails to clot at all. Most people who get a little cut on a finger can put a bandage on the cut, and the cut on the finger will heal because the blood will clot. A blood clot forms from the polymerization of protein fibers that circulate in the blood. A number of protein factors take part in the process, and it is necessary for all of the protein factors to function correctly for blood to clot. Hemophilia exists when any of the factors is either missing or not functioning.
The most common kinds of hemophilia are hemophilia A (or classic hemophilia) and hemophilia B (or Christmas hemophilia), which was named after the first person known to have contracted it. Hemophilia A occurs when clotting factor 8 is not functioning properly; 85% of those who suffer from hemophilia have hemophilia type A. Hemophilia B occurs when factor 9 is not functioning properly; almost all of the rest of those who suffer from hemophilia have hemophilia B.
Hemophilia is generally passed from mother to son, though sometimes it seems to develop spontaneously in some women. Women carry recessive gene but do not generally develop the disease. A mother who carries the defective gene may or may not pass it on to her children. If a mother passes the defective gene to a daughter, the daughter will carry the gene but will most likely not develop the disease. If a mother passes the defective gene to a son, then the son will most likely develop the disease.
Probably the most famous case of hemophilia is often called Royal hemophilia. In this case, Queen Victoria of England, who lived from 1819-1901, was a carrier of the mutating factor 8 that leads to hemophilia type A. Queen Victoria may have inherited the mutated gene from one of her parents, though there is no sign of the mutated gene in the families of Victoria’s parents up to that time that she was born. The mutated factor 8 may also have mutated spontaneously in Victoria, as seems to happen sometimes.
However Victoria came to be a carrier of the gene with the mutated factor, she unfortunately passed it on to some of her children. She had nine children, and three of them, her daughters Alice and Beatrice and her son Leopold, received the mutated gene from their mother. Victoria’s daughters then intermarried with other royal houses of Europe and carried the disease with them. Through Queen Victoria’s daughter Beatrice, the disease was carried into the royal family of Spain. Through Queen Victoria’s daughter Alice, the disease was introduced into the royal families of Austria and Russia, though the disease no longer exists in the Russian family because Victoria’s granddaughter Alexandra and her children were all killed during the Russian revolution.