HDAC9 and autoimmune thrombocytopenic purpura: In disorders with immune deregulation involved in the pathogenesis, low-dose HDAC inhibitors were reported to enhance the number and function of Foxp31 regulatory T (Treg) cells and to enhance immunosuppression and tucidinostat showed potential as a novel treatment for idiopathic thrombocytopenic purpura (ITP) in the clinic (Zhao et al., 2019).