Thrombasthenia

Thrombasthenia is a platelet function disorder characterized by defective platelet aggregation due to deficiency or dysfunction of the platelet integrin alphaIIb beta3 (GPIIb/IIIa). The best known form is Glanzmann thrombasthenia, a rare inherited condition.

It is usually autosomal recessive; mutations in ITGA2B or ITGB3 genes impair expression or function of GPIIb/IIIa on platelets. Platelets appear normal in number and morphology, but cannot properly aggregate to form a hemostatic plug.

Clinically, patients have mucocutaneous bleeding from infancy or childhood, including frequent epistaxis, gingival bleeding, easy bruising, and menorrhagia, with abnormal bleeding after dental procedures or surgery. Bleeding can be persistent and sometimes life-threatening, particularly in the setting of trauma or procedures.

Laboratory features include a normal platelet count, prolonged bleeding time, and abnormal platelet aggregation testing with ADP, collagen, epinephrine, and thrombin; ristocetin-induced aggregation is typically normal. Flow cytometry shows reduced or absent surface GPIIb/IIIa on platelets. Genetic testing can confirm ITGA2B or ITGB3 mutations. The profile helps distinguish thrombasthenia from Bernard-Soulier syndrome (GPIb deficiency with large platelets) and von Willebrand disease.

Treatment focuses on bleeding control and prevention. Measures include local hemostasis, antifibrinolytics such as tranexamic acid, and platelet transfusions for significant bleeding or before surgeries (with risk of alloimmunization and transfusion refractoriness). In refractory cases, recombinant activated factor VIIa may be used. Management is multidisciplinary, including dental care and genetic counseling. Prognosis varies with severity and access to care; with proper management, many bleeding episodes can be controlled.