Lysine-specific histone demethylase 1A (LSD1) also known as lysine (K)-specific demethylase 1A (KDM1A) is a protein that in humans is encoded by the KDM1A gene.[5] LSD1 is a flavin-dependent monoamine oxidase, which can demethylate mono- and di-methylated lysines, specifically histone 3, lysine 4 (H3K4). Other reported methylated lysine substrates such as histone H3K9 and TP53 have not been biochemically validated.[6] This enzyme plays a critical role in oocyte growth, embryogenesis, hematopoiesis and tissue-specific differentiation.[7] LSD1 was the first histone demethylase to be discovered though more than 30 have since been described.[8]