Because of the inflammatory phenotype seen in TTP-deficient mice, initial studies primarily reported on Gr-1+ granulocytes, where the number of mature granulocytes increased in the bone marrow of adult mice deficient in TTP (14), and that CD11b+Gr-1+ cells (a bulk MDSC phenotype) accumulated in the bone marrow and spleen of young TTPKO mice (38). The gene discussed is ZFP36; the disease is thrombotic thrombocytopenic purpura.