Queen Victoria and Prince Albert had 9 children, 4 boys and 5 girls. Prince Leopold was the only one to have hemophilia. Leopold married and had 2 children. His daughter Princess Alice was a carrier of the mutated gene. He died at the age of 30 after a fall which injured his knee and head.

Two of Victoria's daughters, Princesses Alice and Beatrice, were confirmed carriers of the gene. They and several granddaughters passed hemophilia to many of the royal families of Europe including the houses of Bourbon of Spain and Romanov of Russia. The disease has since died out in all of the remaining royal families of Europe.

Examination of the Romanov remains shows that the royals likely had type B Hemophilia. Hemophilia B, also called factor IX (FIX) deficiency or Christmas disease, is a genetic disorder caused by missing or defective factor IX, a clotting protein, causing excessive bleeding. Although it is passed down from parents to children about 1/3 of cases are caused by a spontaneous mutation, a change in a gene.

According to the US Centers for Disease Control and Prevention, Hemophilia occurs in approximately 1 in 5,000 live births. All races and ethnic groups are affected. Hemophilia B is four times less common than Hemophilia A.

More Info: en.wikipedia.org