Diagnosis, clinical features and molecular assessment of the dysfibrinogenaemias.

Hereditary dysfibrinogenaemia is characterized by the presence of functionally abnormal plasma fibrinogen. Dysfibrinogenaemia is a heterogeneous disorder associated with different mutations throughout the three genes that code for the fibrinogen sub-units, affecting many different aspects of fibrinogen/fibrin activity. Dysfibrinogenaemia may be discovered during the investigation of individuals who present with bleeding or thombosis, or may be found in individuals during routine coagulation screening. More specialized coagulation tests may confirm the diagnosis of dysfibrinogenaemia but do not reliably distinguish between the different fibrinogen variants and are not usually useful in predicting bleeding or thrombotic risk. Advances in molecular diagnostics have facilitated the investigation of the molecular causes of fibrinogen disorders. Several 'hot spot' areas have been identified where mutations causing a high proportion of cases of dysfibrinogenaemia are found (AalphaArg16 and gammaArg275). Molecular diagnostics have also shown that many fibrinogen variants share the same causative mutation. There is a discrepancy between the quality of the molecular and functional data available for each mutation and the clinical information on individuals and their family members. However, there are accumulating data that the 'hot spot' mutations accounting for 60-80% of cases of dysfibringenaemia are not associated with a significant bleeding or thrombosis in the absence of other risk factors. Rapid screening for these mutations may provide reassurance for patients in the presurgical setting.