Fibrinogen deficiency, also known as factor I deficiency, is a rare inherited bleeding disorder related to

fibrinogen Fibrinogen (coagulation factor I) is a glycoprotein protein complex, complex, produced in the liver, that circulates in the blood of all vertebrates. During tissue and vascular injury, it is converted Enzyme, enzymatically by thrombin to fibrin ...

function in the

coagulation cascade Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The process of coagulat ...

. It is typically subclassified into four distinct fibrinogen disorders: afibrinogenemia, hypofibrinogenemia, dysfibrinogenemia, and hypodysfibrinogenemia. *

Congenital afibrinogenemia Congenital afibrinogenemia is a rare, genetically inherited blood fibrinogen disorder in which the blood does not clot normally due to the lack of fibrinogen, a blood protein necessary for coagulation. This disorder is autosomal recessive, meaning ...

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. Within the United States, afibrinogenemia accounts for 24% of all inherited abnormalities of fibrinogen, while hypofibrinogenemia and dysfibrinogenemia account for 38% each. * Congenital hypofibrinogenemia is defined as a partial deficiency of fibrinogen, clinically 20–80/deciliter of plasma. Estimated frequency varies from <0.5 to 3 per million. * Dysfibrinogenemia may be congenital or acquired, and is defined as malfunctioning or non-functioning fibrinogen in the blood, albeit at normal concentrations: 200–400 mg/deciliter of plasma. The congenital disorder is estimated to a frequency varying between 1 and 3 per million. * Congenital hypodysfibrinogenemia is an extremely rare, partial deficiency of fibrinogen that is also malfunctioning. Clinically, these disorders are generally associated with an increased diathesis, i.e. propensity, to develop spontaneous bleeding episodes and excessive bleeding after even minor tissue injuries and surgeries; however, individuals with any of these disorders may also exhibit a propensity to pathological

thrombosis Thrombosis () is the formation of a Thrombus, blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel (a vein or an artery) is injured, the body uses platelets (thrombocytes) and fib ...

episodes. Treatment of these disorders generally involves specialized centers and the establishment of preventive measures designed based on each individuals personal and family histories of the frequency and severity of previous bleeding and thrombosis episodes, and, in a select few cases, the predicted propensity of the genetic mutations which underlie their disorders to cause bleeding and thrombosis.

Signs and symptoms

Afibrinogenemia is typically the most severe of the three disorders. Common symptoms include bleeding of the umbilical cord at birth, traumatic and surgical bleeding, GI tract, oral and mucosal bleeding, spontaneous splenic rupture, and rarely intracranial hemorrhage and articular bleeding. Symptoms of hypofibrinogenemia varies from mild to severe, but can include bleeding of the GI tract, oral and mucosal bleeding, and very rarely intracranial bleeding. More commonly it presents during traumatic bleeding or surgical procedures. Most cases (60%) of dysfibrinogenemia are asymptomatic, but 28% exhibit hemorrhaging similar to that described above while 20% exhibit thrombosis (i.e. excessive clotting).

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 Cirrhosis, also known as liver cirrhosis or hepatic cirrhosis, chronic liver failure or chronic hepatic failure and end-stage liver disease, is a chronic condition of the liver in which the normal functioning tissue, or parenchyma, is replaced ...

). 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.

Diagnosis

Treatment

The most common type of treatment is

cryoprecipitate Cryoprecipitate, also called cryo for short, or Cryoprecipitate Antihemophilic factor (AHF), is a frozen blood product prepared from blood plasma. To create cryoprecipitate, plasma is slowly thawed to 1–6 °C. A cold-insoluble precipita ...

a fibrinogen concentrate used in a

drip Drip, The Drip, or DRIP may refer to: * Drop (liquid) Biology and medicine * Intravenous therapy * Vitamin D receptor interacting protein (DRIP) * Mesomycetozoea, a class of eukaryotes (also known as ''DRIP clade'') * Murphy drip, in proctocl ...

to increase fibrinogen levels to normal during surgical procedures or after trauma. RiaSTAP, a factor I concentrate, was approved by the U.S. FDA in 2009 for use when the fibrinogen level was below 50 mg/deciliter of plasma. Recently,

antifibrinolytic Antifibrinolytics are a class of medication that are inhibitors of fibrinolysis. Examples include aminocaproic acid (ε-aminocaproic acid) and tranexamic acid. These lysine Lysine (symbol Lys or K) is an α-amino acid that is a precursor ...

s have also been used to inhibit

fibrinolysis Fibrinolysis is a process that prevents blood clots from growing and becoming problematic. Primary fibrinolysis is a normal body process, while secondary fibrinolysis is the breakdown of clots due to a medicine, a medical disorder, or some other c ...

(breaking down of the fibrin clot). In the case of dysfibrinogenemia that manifests by

, anticoagulants can be used. Due to the inhibited clotting ability associated with a- and hypofibrinogenemia, anticoagulants including

aspirin Aspirin () is the genericized trademark for acetylsalicylic acid (ASA), a nonsteroidal anti-inflammatory drug (NSAID) used to reduce pain, fever, and inflammation, and as an antithrombotic. Specific inflammatory conditions that aspirin is ...

are advised against.

References

External links

{{Medical resources , ICD10 = {{ICD10, D68.2 , ICD9 = , ICDO = , OMIM = 610984 , DiseasesDB = , MedlinePlus = , eMedicineSubj = , eMedicineTopic = , MeSH = , GeneReviewsNBK = , GeneReviewsName = , Orphanet = 200418 Coagulopathies Congenital disorders