Les thrombopénies constitutionnelles. De la clinique aux actualités génétiques

Investigating a chronic thrombocytopenia is a usual matter for a pediatrician. The most frequent diagnosis is autoimmune thrombocytopenia. However in case of unusual presentation or evolution, syndromic association, familial history of thrombocytopenia or myeloid malignancy, the hypothesis of a constitutional thrombocytopenia has to be considered. This is a large spectrum of diseases with different prognosis and evolution. It has benefited from the inputs of genetics and molecular biology over the past few years. Recent genetic knowledge enabled the description of several diseases. Being aware of these new entities is crucial for a better characterization of the diseases, in order to adapt the management strategy to each specific feature. Considering the growing number of new genes and new mutations described, we propose a classification of genetic thrombocytopenias relaying on two simple parameters: the isolated or syndromic pattern of the thrombocytopenia and on the mean platelet size and volume, based on a recent literature review. We aimed at demonstrating the diagnosis algorithm with simple clinical and biological data among a moving spectrum of diseases. However, nowadays half constitutional thrombocytopenias remain genetically undiagnosed. This proportion should be decreased in the next years, which will lead to a better management of the patients.