HDAC9 and B-cell chronic lymphocytic leukemia: The high expression of HDAC has been confirmed in the study conducted by Wang et al. in chronic lymphocytic leukemia (CLL) patients with a significant increase in HDAC of class I including HDAC1 and HDAC3, class II including HADC6, HDAC7, HDAC9, and HDAC10, and class III including SIRT1 and SIRT6 [62].