This session will cover topics from the lab through to the clinic, including differences between clotting factor VIII and IX deficiencies in female carriers and their underlying mechanisms, as well as the unmet clinical needs of women and girls with haemophilia. Furthermore, discrepancies among clotting factor activity assays, their impact on factor replacement therapy and practical solutions to address those will be discussed. Finally, the various reasons for and the impact of a delayed diagnosis of rare bleeding disorders, focusing on women, infants and mobile populations, will be examined.