Inherited disorders of platelet function in pediatric clinical practice: a diagnostic challenge.

Hereditary disorders of platelet function are a heterogeneous group of diseases that are often complex and tend to go undetected until clinically relevant bleeding occurs. Hallmarks are epistaxis, easy bruising, mucous membrane bleeding, perioperative bleeding and menorrhagia. Bleeding may be intermittent and unpredictable. After decades of successful research on platelet biology and genetics, research findings have not been satisfactorily translated to clinical practice. The lack of robust and well- standardized test systems continues to make the diagnosis of platelet defects cumbersome for the practising clinician. Patient history and description of clinical bleeding symptoms are essential. Exclusion of von Willebrand disease, platelet count and investigation of blood smears may provide a tentative diagnosis. Light transmission aggregometry is still considered the gold standard for assessing platelet function. Due to the wide range of possible genetic defects molecular biological analyses can complement but do not substitute for other tests. The true incidence of inherited disorders of platelet function is unknown. A survey in Germany revealed that receptor-defects including Glanzmann's thrombasthenia and Bernard-Soulier syndrome and aspirin-like defects were the most frequently diagnosed platelet disorders. Of affected children 60% presented with mild and 40% with moderate to severe bleeding tendency. Epistaxis, cutaneous and mucous membrane bleeding were the most frequent symptoms. The paediatric competence network of the GTH e.V. comprises 44 collaborating centres that are caregivers to over 150 children with well-defined inherited platelet defects. A major goal of this network is to promote diagnosis of children with inherited disorders of platelet function.