Introduction: Rare Bleeding Disorders: General Aspects of Clinical Features, Diagnosis, and Management

Rare bleeding disorders (RBDs) are autosomal recessive diseases including the inherited deficiencies of coagulation factors such as fibrinogen, factor (F) II, FV, FV + FVIII, FVII, FX, FXI, FXIII, and multiple deficiency of vitamin K-dependent factors, with clinical manifestations ranging from mild to severe. They represent 3 to 5% of all the inherited coagulation deficiencies with a prevalence in the general population varying between 1 in 500,000 and 1 in 2 million, being higher in areas where consanguineous marriages are diffuse. Despite the progress made in past years, as a consequence of the rarity of these deficiencies, the type and severity of bleeding symptoms, the underlying molecular defects, the actual management of bleeding episodes and particularly the prophylactic treatment in patients affected with RBDs are not well established. In this introductory article, the main features, diagnosis, available treatment options, and treatment complications of RBDs will be discussed.