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Factor I deficiency, 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.〔〔(【引用サイトリンク】title=Inherited Abnormalities of Fibrinogen )〕 ''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.〔 == Causes == The disorders associated with Factor I deficiency are generally inherited,〔〔 although certain liver diseases can also affect fibrinogen levels and function (e.g. cirrhosis). Afibrinogenemia is a recessive inherited disorder, where both parents must be carriers.〔 Hypofibrinogenemia and dysfibrinogenemia can be dominant (i.e. only one parent needs to be a carrier) or recessive.〔 The origin of the disorders is traced back to three possible genes: FGA, FGB, or FGG. Because all three are involved in forming the hexameric glycoprotein fibrinogen, mutations in any one of the three genes can cause the deficiency. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Factor I Deficiency」の詳細全文を読む スポンサード リンク
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