A multitude of studies have investigated the plasma concentration of VEGF in MDD patients, but the data and interpretation remain conflicting possibly due to the differences in study designs (see review by Clark-Raymond and Halaris 2013) In addition, as mentioned above, there is currently no evidence that blood levels of neurotrophins reflect those of the brain, making causal inferences of the role of VEGF in MDD based on blood concentrations rather speculative. The gene discussed is BDNF; the disease is major depressive disorder.