Moreover, 55% of BD patients included in the study had increased transcription of the phosphodiesterase 4B (PDE4B) gene, which codes for a pro-inflammatory, cAMP-degrading enzyme expressed in immune cells; this enzyme has been proven to play an essential role in the pathophysiology of many psychiatric and neurological diseases (Fatemi et al., 2008; Padmos et al., 2008). Here, PDE4B is linked to nervous system disorder.