In 1924, a family from the remote Åland Islands between Sweden and Finland brought their 5-year old daughter to a Helsinki physician, Professor Erik von Willebrand, for investigation of a severe bleeding disorder. This girl suffered from recurrent mucosal bleeding and was later to die at age 13 from uncontrollable menstrual haemorrhage. Her parents were third cousins and both had bleeding symptoms, as did 10 of her 11 siblings, von Willebrand began an extensive study of this family and concluded that they suffered from a previously undescribed bleeding disorder (von Willebrand, 1926). Later studies found that these patients were deficient in a plasma factor, now termed von Willebrand Factor (vWF).