Glanzmann’s Thrombasthenia

At a glance

Genetic platelet disorder resulting in blood clotting disorder and hemorrhage. The disease is usually diagnosed in young ages after epistaxis or mucocutaneous bleeding. Complaints such as easy bruising, muscle hematomas, hemarthrosis gastrointestinal bleeding, menorrhagia, and hematuria appear in further stages of life. This medical condition is associated with life-threatening conditions when the patient is exposed to stress (eg, surgery, anesthesia). It is an extremely rare coagulopathy disorder in which the platelets contain defective or low levels of glycoprotein IIb/IIIa (GpIIb/IIIa), which is a receptor for fibrinogen. As a result, no fibrinogen bridging of platelets to other platelets can occur, and the bleeding time is significantly prolonged.

Synonyms

Athrombocytopenic Purpura; Congenital Hemorrhagic Thrombocytic Dystrophy; Glanzmann Syndrome; Glanzmann-Naegeli Syndrome; Glycoprotein IIb (GPIIb/III) Complex Deficiency; Hemorrhagic Thrombasthenia; Hereditary Thrombasthenia; Hereditary Thrombocytopenic Purpura; Naegeli Syndrome II; Platelet Fibrinogen Receptor Deficiency; Platelet Glycoprotein IIb/III Deficiency; Révol Syndrome; Thrombasthenia; Thrombocytasthenia; Thrombocytopathic Purpura.

History

This medical condition was first described in 1918 by Eduard Glanzmann (1887-1959), a Swiss pediatrician, and Otto Nägeli (1871-1938), a Swiss hematologist.

Incidence

Glanzmann thrombasthenia (GT) is a rare disorder with an incidence established approximately 1:1,000,000. There are 200 cases reported in the literature. It is also suggested that it is more common in people of Romani ethnicity, particularly within the French Manouche community.

Genetic inheritance

Autosomal recessive disorder in one of two genes of chromosome 17, either GPIIb (or integrin αIIbß3) or GPI-IIIa (or integrin αIIbβ3), where GP indicates glycoprotein that act as a fibrinogen receptor on the surface of thrombocytes to facilitate adherence and aggregation. Genetic mutations split equally between GPIIb and GPIIIa. Some cases may be transmitted as an autosomal dominant trait.

Pathophysiology

In platelets, GPIIb and GPIIIa are joined together as a dimer (referred to as GPIIb/IIIa). Once activated, GPIIb/IIIa binds to one end of fibrinogen (and/or von Willebrand factor), while another platelet, with its own GPIIb/IIIa, can bind to the other extremity of the fibrinogen, thus leading to a large aggregation of bound platelets (so-called white blood clot). In patients with Glanzmann thrombasthenia, GPIIb/IIIa is defective and platelets cannot aggregate; no blood clot is formed and bleeding does not stop.

Diagnosis

Normal to increased platelet count, giant platelets, absent platelet surface thrombosthenin, prolonged bleeding time, poor clot retraction, and absent platelet aggregation. Adenosine diphosphate-induced platelet aggregation does not occur.

Clinical aspects

Bleeding diathesis, petechiae, and anemia. Two forms described:

• Type I: Severely affected patients, especially girls at time of menarche.

• Type II: It is the mild form.

Precautions before anesthesia

Check complete blood count (CBC). Ensure ...