In both clinical and preclinical studies, the researchers reported that the genes that are important for differentiation, maturation of oligodendrocytes, and myelin structure (miR-92a-3p, NRG1, FGF2, MAG, MAL, PMP22, PLLP, PLP1) were significantly downregulated in MDD and suicide. This evidence concerns the gene PLP1 and major depressive disorder.