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Glanzmann thrombasthenia (GT) is a bleeding syndrome affecting the megakaryocyte lineage and characterized by lack of platelet aggregation. The syndrome is rare but the prevalence is unknown. GT is associated with clinical variability: some patients have only minimal bruising while others have frequent, severe and potentially fatal hemorrhages. The site of bleeding in GT is clearly defined: purpura, epistaxis, gingival hemorrhage, and menorrhagia are nearly constant features; gastrointestinal bleeding and hematuria are less common. In most cases, bleeding symptoms manifest rapidly after birth, even if GT is occasionally only diagnosed in later life. The syndrome is transmitted as an autosomal recessive trait. The molecular basis is linked to quantitative and/or qualitative abnormalities of the alphaIIb beta3 integrin. This receptor mediates the binding of adhesive proteins that attach aggregating platelets and ensure thrombus formation at sites of injury in blood vessels. Diagnosis is based on the association of mucocutaneous bleeding with absent platelet aggregation in response to all physiologic stimuli, and a normal platelet count and morphology. Platelet alphaIIb beta3 deficiency or nonfunction should always be confirmed, by flow cytometry for example. In order to avoid platelet allo immunization, therapeutic management must include, if possible, local hemostatic procedures and/or DDAVP (desmopressin) administration. If these measures are ineffective, or to prevent bleeding during surgery, management often requires the transfusion of HLA-compatible platelet concentrates. Administration of recombinant factor VIIa is an increasingly used therapeutic alternative. GT can be a severe hemorrhagic disease, however the prognosis is excellent with careful supportive care. |