Diagnosis of inherited bleeding disorders in the genomic era.

Inherited bleeding disorders affect between 1 in 1000 individuals for the most common disorder, von Willebrand Disease, to only 8 reported cases worldwide of alpha-2-antiplasmin deficiency. Those with an identifiable abnormality can be divided into disorders of coagulation factors (87%), platelet count and function (8%) and the fibrinolytic system (3%). Of the patients registered in the UK with a bleeding disorder, the remaining 2% are unclassifiable. In addition to bleeding symptoms, patients with an inherited bleeding disorder can manifest other abnormalities, making an accurate and complete diagnosis that reflects the underlying molecular pathology important. Although some inherited bleeding disorders can still be easily diagnosed through a combination of careful clinical assessment and laboratory assays of varying degrees of complexity, there are many where conventional approaches are inadequate. Improvements in phenotyping assays have enhanced our diagnostic armoury but genotyping now offers the most accurate and complete diagnosis for some of these conditions. The advent of next generation sequencing technology has meant that many genes can now be analysed routinely in clinical practice. Here, we discuss the different diagnostic tools currently available for inherited bleeding disorders and suggest that genotyping should be incorporated at an early stage in the diagnostic pathway.