HDAC9 and myelodysplastic syndrome: Recently, 5AZA, a hypomethylating agent [126], together with HDAC inhibitors, such as trichostatin A (TSA), sodium butyrate (NaBu) [127], SAHA [128] and LBH589 [129], have been approved by the Food and Drug Administration (FDA) of the USA for cancer therapy in myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML) [130].