On Apr. 17, 1989, World Hemophilia Day was started and the World Federation of Hemophilia (WFH) chose April 17 in honor of founder Frank Schnabel, who was born on that day.  The WFH is a non-profit organization dedicated to improving and sustaining care for people with inherited bleeding disorders around the world.

Hemophilia is a rare disorder in which the blood doesn’t clot in the typical way because it doesn’t have enough blood-clotting proteins (clotting factors). If you have hemophilia, you might bleed for a longer time after an injury than you would if your blood clotted properly.

If you have a severe form of the condition, the main concern is bleeding inside your body, especially in your knees, ankles and elbows. Internal bleeding can damage your organs and tissues and be life-threatening.