Impaired function of thrombocytes, especially in regard to aggregation and clot retraction; any condition characterized by this, specifically (more fully "hereditary haemorrhagic thrombasthenia" or "Glanzmann('s) thrombasthenia") an inherited (autosomal recessive) disorder manifesting itself mainly as episodes of bleeding from the mucosal surfaces of the nose, uterus, and gastrointestinal tract.