LAUSR

Fibrinogen is a 340 kDa hexameric glycoprotein synthetized by hepatocytes. It is composed by three polypeptide chains Aα, Bβ, and γ.1 Three genes are implicated in fibrinogen synthesis: FGA, FGB, and FGG for Aα, Bβ and γ chain respectively.2 Fibrinogen circulates in plasma and a pool of fibrinogen is stored in platelets α-granules. Both megakaryocytes and platelets are able to internalize plasma fibrinogen via the fibrinogen receptor: the glycoprotein IIb/IIIa (GpIIb-IIIa; αIIbβ3).1 Fibrin polymerization is initiated by the thrombin mediated-cleavage of fibrinopeptides A and B. Congenital fibrinogen disorders are distinguished in two categories.1 Type I is a quantitative fibrinogen deficiency which can be subdivided in hypofibrinogenemia and afibrinogenemia, corresponding to reduction of fibrinogen or lack of fibrinogen. Type II is a qualitative fibrinogen characterized by normal (dysfibrinogenemia) or decreased levels (hypodysfibrinogenemia) of dysfunctional fibrinogen. The main consequence of fibrinogen deficiency is an increased bleeding risk as a result of lack of fibrin formation. However, thrombotic risk is also enhanced in these patients. Here we present a clinical case of a newborn with cephalhematoma leading to the diagnosis of congenital afibrinogenemia.