PRDM9 and schizophrenia: Methylation of H3K4 is known to specifically ‘tag' genes for epigenetic transcriptional activation.26, 27PRDM9 is expressed in germ cells during meiotic prophase and its disruption inhibits prophase progression leading to sterility.28 Meiotic recombination events cluster into narrow segments of the genome, defined as hotspots and PRDM9 plays a role in determination of these recombination hotspots.29, 30, 31 In the past PRDM9 was not on the radar as a schizophrenia candidate gene as genomic alterations that occur during meiosis are not detected using standard genetic mapping techniques.