Hemophilia is a congenital hereditary disease, a group of hereditary bleeding disorders that cause severe clotting disorders in patients due to the lack of certain clotting factors in the blood. It can occur in both men and women, but the vast majority of patients are male, including hemophilia A, hemophilia B and hemophilia C. The former two are sex-linked recessive, while the latter is autosomal incomplete recessive. Hemophilia is known as a royal disease, originating from the European royal system of the 1820s. Queen Victoria was a carrier of the hemophilia gene. Queen Victoria is known for bringing hemophilia into the European royal family, and since there was no genetic history of hemophilia in her paternal or maternal lines or ancestors, scientists hypothesize that a genetic mutation occurred in Victoria and she became a carrier of the hemophilia gene. Queen Victoria’s sons and daughters were married to European royals, spreading hemophilia to many of the royal families of Europe, and thus hemophilia became known as a royal disease.