Hemophilia is a rare genetic blood disorder characterized by the inability or deterioration of the blood to clot or coagulate when a blood vessel is ruptured. This hereditary disease is caused by an insufficiency of blood proteins, known as factors, that participate in blood clotting, often through a sudden genetic mutation. Hemophilia can be characterized into three distinct types, including hemophilia A, hemophilia B, and hemophilia C. Biologically, hemophilia is a unique genetic disorder that, as a sex-linked recessive disorder, has major more likely to occur in males than in females. This is explained by the fact that females have two X chromosomes, while males only have one, so the faulty gene is guaranteed to show up in any male who carries it. Because females have two X chromosomes in their genetic makeup and hemophilia is rare, the possibility of a female having two defective copies of the gene is very remote. Females are almost exclusively asymptomatic carriers of the disease, meaning they do not show symptoms of hemophilia, but have the ability to transmit the disease to their offspring. An asymptomatic carrier mother of hemophilia has a 50% chance of passing the defective X chromosome to her daughter, and an affected father will always pass the defective gene to his daughters (a son cannot inherit the defective gene from his father). . The transmission pattern of hemophilia can be described as a crossover type, which is also seen in color blindness (another genetic disease). With all genetic diseases, including hemophilia, it is possible for a human to acquire it spontaneously as a result of genetic mutation, defined as a change in the nucleotide sequence in an organism's genome. Mutations that cause hemophilia... half of the document... Historic scientific discoveries about hemophilia contribute largely to the modern understanding and treatment of the disease. Hemophilia was also historically coined the "royal disease" due to its prominence in European royalty. Queen Victoria of England (r. 1837-1901) passed the hemophilia B mutation to her son Leopold, and through several of her daughters, the genetic mutation was passed on to various royals across the continent. The influence of hemophilia eventually spread to the royal families of Spain, Germany, and Russia. In Russia, Tsar Nicholas II (r. 1894-1917) had a hemophiliac son who claimed to be cared for by the controversial figure and friend of the royal family, Grigori Rasputin. The possession of hemophilia among European royalty suggests that this genetic disease can affect any human being, his ethnicity and social status being irrelevant..