Starting 90 years ago with a clinical description by Glanzmann of a
bleeding disorder associated with a defect in platelet function, technologic advances helped investigators identify the defect as a mutation(s) in the
integrin family receptor, alphaIIbbeta3, which has the capacity to bind
fibrinogen (and other
ligands) and support platelet-platelet interactions (aggregation). The receptor's activation state was found to be under exquisite control, with activators, inhibitors, and elaborate inside-out signaling mechanisms controlling its conformation. Structural biology has produced high-resolution images defining the
ligand binding site at the atomic level. Research on alphaIIbbeta3 has been bidirectional, with basic insights resulting in improved
Glanzmann thrombasthenia carrier detection and prenatal diagnosis, assays to identify single nucleotide polymorphisms responsible for alloimmune
neonatal thrombocytopenia, and the development of alphaIIbbeta3 antagonists, the first rationally designed
antiplatelet agents, to prevent and treat thrombotic
cardiovascular disease. The future looks equally bright, with the potential for improved drugs and the application of gene therapy and stem cell biology to address the genetic abnormalities. The alphaIIbbeta3 saga serves as a paradigm of rigorous science growing out of careful clinical observations of a rare disorder yielding both important new scientific information and improved diagnosis,
therapy, and prevention of other disorders.