What is Hemophilia? What is Haemophilia?

Hemophilia is a group of inherited blood disorders in which the blood does not clot properly.
Hemophilia is the standard international spelling, also known as haemophilia in the UK, other translations include: hémophilie, hemofilie, hemofili, hemofilia, hämophilie, emofilia. We will use the standard international spelling for the purpose of this section.
Bleeding disorders are due to defects in the blood vessels, the coagulation mechanism, or the blood platelets. An affected individual may bleed spontaneously or for longer than a healthy person after injury or surgery.
The blood coagulation mechanism is a process which transforms the blood from a liquid into a solid, and involves several different clotting factors. The mechanism generates fibrin when it is activated, which together with the platelet plug, stops the bleeding.
When coagulation factors are missing or deficient the blood does not clot properly and bleeding continues.
Patients with Hemophilia A or B have a genetic defect which results in a deficiency in one of the blood clotting factors.
Queen Victoria was a carrier and passed the mutation to her son Leopold, and through several of her daughters to members of the royal families of Spain, Russia, and Germany.
Tsarevich Alexei Nikolaevich, son of Nicholas II (Russia) suffered from hemophilia and was a descendant of Queen Victoria - Rasputin was successful in treating his hemophilia, it was claimed.