However, investigations on epigenetic changes in BDNF have been described in individuals with psychiatric disorders and neurodegenerative diseases, including depression, Huntington's disease, and schizophrenia (Ikegame et al., 2013; Zheleznyakova et al., 2016; Di Carlo et al., 2019; Gutierrez et al., 2020). The gene discussed is BDNF; the disease is major depressive disorder.