The increased expression of histone-modifying enzymes, such as KDM1A, histone deacetylase 2 (HDAC2), and NAD-dependent deacetylase sirtuin-1 (SIRT1), was observed in breast cancer samples, and their overexpression was shown to be associated with reduced survival and a shorter period of tumor relapse [133]. The gene discussed is KDM1A; the disease is breast cancer.