To date, the vast majority of reports studying HDAC isoforms and heart tissue have been carried out in mouse models; however, there are obvious differences between the mouse and the human.124 Different methods of assessing the role of HDAC knockdown may also affect results.125 Thus, the findings of these studies may not represent the true role of HDACis on human heart disease and development. The gene discussed is HDAC9; the disease is heart disorder.