Qualitative disorders of platelets and megakaryocytes

J Thromb Haemost. 2005 Aug;3(8):1773-82. doi: 10.1111/j.1538-7836.2005.01428.x.


Qualitative disorders of platelet function and production form a large group of rare diseases which cover a multitude of genetic defects that by and large have as a common symptom, excessive mucocutaneous bleeding. Glanzmann thrombasthenia, is enabling us to learn much about the pathophysiology of integrins and of how alphaIIb beta3 functions. Bernard-Soulier syndrome, an example of macrothrombocytopenia, combines the production of large platelets with a deficit or non-functioning of the major adhesion receptor of platelets, the GPIb-IX-V complex. Amino acid substitutions in GPIb alpha, may lead to up-regulation and spontaneous binding of von Willebrand factor as in Platelet-type von Willebrand disease. In disorders with defects in the MYH9 gene, macrothrombocytopenias are linked to modifications in kidney, eye or ear, whereas other inherited thrombocytopenias variously link a low platelet count with a propensity to leukemia, skeletal defects, learning impairment, and abnormal red cells. Defects of secretion from platelets include an abnormal alpha-granule formation as in the gray platelet syndrome (with marrow myelofibrosis), and of organelle biogenesis in the Hermansky-Pudlak and Chediak-Higashi syndromes where platelet dense body defects are linked to abnormalities of other lysosomal-like organelles including melanosomes. Finally, defects involving surface receptors (P2Y(12), TPalpha) for activating stimuli, of proteins essential for signaling pathways (including Wiskott-Aldrich syndrome), and of platelet-derived procoagulant activity (Scott syndrome) show how studies on platelet disorders are helping unravel the pathways of primary hemostasis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Bernard-Soulier Syndrome / blood
  • Blood Platelet Disorders / blood*
  • Blood Platelet Disorders / diagnosis*
  • Blood Platelets / metabolism
  • Coagulants
  • Genetic Therapy / methods
  • Humans
  • Integrins / metabolism
  • Megakaryocytes / cytology
  • Megakaryocytes / metabolism
  • Megakaryocytes / physiology*
  • Models, Biological
  • Platelet Aggregation
  • Protein Binding
  • Signal Transduction
  • Thrombasthenia / blood
  • Thrombocytopenia / blood
  • Up-Regulation
  • von Willebrand Factor / metabolism


  • Coagulants
  • Integrins
  • von Willebrand Factor