Glanzmann's thrombasthenia

Etiology

• low platelet glycoprotein IIb-IIIa complex
• fibrinogen will not interlink

Epidemiology

most common inherited disease of platelets

Pathology

• congenital platelet defects
• inability of this integrin alpha-2b to recognize macromolecular or synthetic peptide ligands
• type 1: platelets show absence of the glycoprotein IIb/beta-3 complexes at their surface & lack fibrinogen & clot retraction capability
• type 2: platelets express the glycoprotein IIb/beta-3 complex at diminishedlevels (5-20% controls), have detectable amounts of fibrinogen, & have low or moderate clot retraction capability
• normal or near normal (60-100%) expression of dysfunctional receptors

Genetics

• autosomal recessive
• associated with defects in ITGA2B (CD41)

Clinical manifestations

• early hemorrhagic complications in the neonatal period
• hemorrhagic events perists throughout life
  • epistaxis
  • purpura
  • petechiae
  • ecchymoses

Laboratory

• complete blood count (CBC) - platelet count is normal
• peripheral blood smear
  • normal platelet morphology
  • no clumping of platelets
• platelet aggregation
  • defect in the 1st phase of platelet aggregation with: ADP, epinephrine, thrombin or collagen
  • normal platelet aggregation with ristocetin cofactor

Management

• nasal packing & other local hemorrhage control measures
• when local hemorrhage control measures fail
  • epsilon-aminocaproic acid
  • recombinant factor VIIa or platelet transfusion
  • cryoprecipitate with or without platelets

More general terms

• platelet disorder; thromboasthenia

Additional terms

• glycoprotein IIB/IIIA