Rare congenital bleeding disorders.

The rare congenital bleeding disorders are a heterogeneous group of diseases which include deficiencies of fibrinogen, prothrombin and factors V, V + VIII, VII, X, XI and XIII. They are usually transmitted as autosomal recessive disorders, and the prevalence of the severe forms ranges from one case in 500,000 for factor VII up to one in 2,000,000 for factor XIII in the general population. Patients with rare congenital bleeding disorders may have a broad spectrum of clinical symptoms, ranging from mucocutaneous bleeding to life-threatening haemorrhages, such as those occurring in the central nervous system. The treatment of these disorders is based principally on the replacement of the deficient factor using, when available, specific plasma-derived or recombinant products. The aim of this narrative review is to summarise current knowledge about these rare bleeding conditions.