IGF1 and obesity due to melanocortin 4 receptor deficiency: Recent studies have revealed several pleiotropic genes that might be shared between mood disorders and obesity, such as FTO (encoding fatmass and obesity-associated protein), BDNF (encoding brain-derived neurotrophic factor), POMC (encoding proopiomelanocortin), and IGF1 (encoding insulin-like growth factor 1), as well as shared genetic pathways involving serotonin and dopamine receptor signaling, leptin signaling, circadian rhythm signaling, axonal guidance signaling, and corticotropin-releasing hormone signaling [34].