After G9a overexpression in vitro and in vivo, the enrichment levels of H3K9me2 in the promoter region of BDNF were augmented, whereas the levels of BDNF were decreased, along with damaged neurons and impaired learning and memory abilities of rats with hypoxic-ischemic encephalopathy [29]. This evidence concerns the gene BDNF and perinatal asphyxia.