BDNF and Iron deficiency anemia: In the context of histone mark changes or histone methylation changes, iron-deficiency in the fetal-neonatal period induced a change in the methylation of the brain-derived neurotrophic factor (Bdnf) promoter in the rat hippocampus and caused an elevation in the repressive histone marks such as H3K9me3 but a decrease in the activation histone mark H3K4me3 along Bdnf [82].