Abstract
The development of registries through international collaboration has facilitated better understanding of the rare bleeding disorders. Such work has shown that rare bleeding disorders are heterogeneous and need to be studied singularly, and that heterozygous patients may bleed. There is a need to understand the minimum plasma coagulant activity level to prevent spontaneous bleeding. Moreover, due to the low prevalence of rare bleeding disorders, the management of this patient population remains a challenge. Data collection on clinical history, efficacy and side effects of treatment needs to be harmonised.