Thus, presuming that the reduced peripheral BDNF levels observed in BD patients accurately reflect levels in the brain, and considering that BDNF may induce EGR3 expression via PKC/MAPK dependent pathway (Roberts et al., 2006), the decreased levels of BDNF may account, at least in part, for the prefrontal cortex EGR3 repression that we identified in BD (Pfaffenseller et al., 2016). This evidence concerns the gene BDNF and Behcet disease.