Reductions in brain-derived neurotrophic factor (BDNF), a protein of the neurotrophic family of growth factors,[10] has been reported in different neuropsychiatric diseases.[11–14] The BDNF blood levels are decreased in MDD subjects and increase after antidepressant treatment.[15,16] Epigenetic mechanisms are also being investigated in individuals with MDD, especially the regulation of microRNAs level. The gene discussed is BDNF; the disease is major depressive disorder.