Biological features of hereditary fibrinogen disorders and International Society Thrombosis and Hemostasis (ISTH) classification
| Fibrinogen activity | Fibrinogen antigen | Genotype | ISTH classification | |
|---|---|---|---|---|
| Afibrinogenemia | No detectable | No detectable | Homozygous or compound heterozygous for a null* mutation | IA. Bleeding phenotype or asymptomatic individuals IB. Thrombotic phenotype |
| Hypofibrinogenemia | Decreased | Decreased | Heterozygous for a null or missense mutation | 2A. Fibrinogen activity <0.5 g/L (severe) 2B. Fibrinogen activity 0.5 - 0.9 g/L (moderate) 2C. Fibrinogen activity 1- and lower limit of normal value (mild) 2D. Histologically proven accumulation of fibrin in hepatocytes (Fibrinogen storage disease**) |
| Dysfibrinogenemia | Decreased*** | Normal*** | Heterozygous for a missense mutation | 3A. Bleeding phenotype or with thrombotic phenotype not fulfilling criteria for dysfibrinogenemia 3B or asymptomatic individuals 3B. Carriers of a thrombotic fibrinogen mutation**** or suffering from thrombotic events with a first-degree familial thrombotic history (relatives with the same genotype) without any other thrombophilia |
| Hypodysfibrlnogenemla | Decreased | Decreased | Homozygous or compound heterozygosity for a null and/or a missense mutation | 4A. Fibrinogen antigen <0.5 g/L (severe) 4B. Fibrinogen antigen 0.5 - 0.9 g/L (moderate) 4C. Fibrinogen activity 1- and lower limit of normal value (mild) |