<unk> , also known as fibrinogen deficiency, is a rare inherited bleeding disorder related to fibrinogen function in the blood coagulation cascade.  It is typically subclassified into three distinct disorders: afibrinogenemia, hypofibrinogenemia, or dysfibrinogenemia.
Afibrinogenemia is defined as a lack of fibrinogen in the blood, clinically <20 mg/deciliter of plasma.  The frequency of this disorder is estimated at between 0.5 and 2 per million.
Hypofibrinogenemia is defined as a partial deficiency of fibrinogen, clinically 20–80 mg/deciliter of plasma.  Estimated frequency varies from <0.5 to 3 per million.
Dysfibrinogenemia is defined as malfunctioning or non-functioning fibrinogen in the blood, albeit at normal concentrations: 200–400 mg/deciliter of plasma.  Hypodysfibrinogenemia is a partial deficiency of fibrinogen that is also malfunctioning.  Estimated frequency varies from 1 to 3 per million.
Within the United States, afibrinogenemia accounts for 24% of all inherited abnormalities of fibrinogen, while hypofibrinogenemia and dysfibrinogenemia account for 38% each.
Factor I Deficiency
Factor XIII deficiency
Protein S deficiency
Protein C deficiency
Antithrombin III deficiency
Factor V Leiden
Hemophilia
Platelet storage pool deficiency