Although hereditary thrombocytopenia is overall a very rare disorder, many different forms have been well described. Inherited thrombocytopenia is frequently mistaken for an acquired platelet disorder. A careful medical and family history can generally allow differentiating congenital from acquired thrombocytopenia based on the duration of symptoms and the onset early in childhood. A detailed pedigree will often help to identify the inheritance pattern. The recognition of hereditary thrombocytopenia is important for avoiding potentially expensive and harmful treatments, as frequently administered in acquired chronic platelet disorders, and which will furthermore mostly be ineffective.

Some patients with hereditary thrombocytopenia have no clinical symptoms due to the moderate or mild thrombocytopenia and are most often detected by chance, due to the routine automated platelet counting and frequently associated automated mean platelet volume determination, when studying the peripheral blood. For this reason, probably more patients are being detected during recent years. It is only in the last few years that the underlying molecular abnormalities have become obvious. Due to the efforts of many research groups, the responsible gene, the defective gene product and the pathogenesis of many of these disorders have been unravelled. For many of these disorders, the clinical picture was well known and only recently the responsible gene and gene product were discovered. For others, the molecular mechanism was first unravelled in mice, and the human pathology was only discovered and defined by analogy with the animal model. Interestingly, discovering the molecular mechanisms of hereditary thrombocytopenia has led to a better understanding of the normal physiology of hematopoiesis.