We observed a significant increase in serum levels of basic FGF, G-CSF, and GM-CSF in adolescents with MDD (basic FGF: F = 17.25; G-CSF: F = 20.24; and GM-CSF: F = 28.50; in all cases df = 80, 3 and P < 0.0001). This evidence concerns the gene CSF3 and major depressive disorder.