Most of the microRNAs investigated in the studies are suggested to be involved in the mechanisms of neuroplasticity, such as in the expression of brain-derived neurotrophic factor (BDNF), which is an important neurotrophin that is possibly involved in MDD pathophysiology and treatment response to ADs such as miR-1202, miR-124, miR-16, and miR-135 [59,65]. The gene discussed is BDNF; the disease is major depressive disorder.