Why is hemophilia called the Christmas disease?

Hemophilia is not called Christmas disease; rather, hemophilia B is sometimes referred to as Christmas disease.

How Hemophilia B Got its Name

Stephen Christmas was a 5-year-old boy from Canada who bled to death after a tonsillectomy in 1952. His case helped researchers uncover the distinction between hemophilia A and hemophilia B, and as a result, hemophilia B was sometimes referred to as Christmas disease in early medical literature.