PRDM9 and major depressive disorder: The target mRNAs were found to play important roles in the pathogenesis of diabetes mellitus and depression, including histone methylation, cellular metabolic processes, and DNA damage responses, as well as macromolecular functions involved in chromatin regulation, including SUMO ligase activity, histone methyltransferases, mitogen-activated protein kinase (MAPK) activity, and transcription factor binding.