Her father (B:I‐1) was also thrombocytopenic and recovered from AML, her daughter had a normal platelet count, whereas her son (B:III‐1) had a moderate thrombocytopenia varying between 100 and 130 G/L associated with delta granules impaired secretion and high levels of thrombopoietin. This evidence concerns the gene THPO and Thrombocytopenia.