Rare bleeding disorders (RBDs) are very rare diseases, relatively neglected until recently by health care providers, advocacy organizations and pharmaceutical companies. Haemophilia A and B are the most frequent inherited bleeding disorders. Together with von Willebrand disease, a defect of primary hemostasis associated with a secondary defect in coagulation factor VIII (FVIII), these X-linked disorders include 95% to 97% of all the inherited deficiencies of coagulation factors. 1
The other 3-5% are represented by the less common inherited disorders. This include deficiency of fibrinogen, prothrombin, factors V, combined V+VIII, VII, X, XI and XIII. These disorders are inherited in an autosomal recessive manner (Figure 1) and their prevalence is approximately 1:500.000 or less in the general population of western countries (Table 1) 1 However their frequency is increased 10-20 times where consanguineous marriages are practised such as Middle East countries and in Southern India. 2
The natural history and spectrum of clinical manifestations of RBDs are not well established, since few centres in the world have the opportunity to see a significant number of these rare patients.