The endocannabinoid system is physiologically involved in regulation of appetite, pain, mood, memory, inflammation, insulin sensitivity, as well as fat and energy metabolism, with a wide variety of potential therapeutic implications for treatment of pain, neuropsychiatric disorders, neurological diseases, and inflammatory bowel, which may benefit from CB1 activation, as well as for treatment of obesity, type 2 diabetes, and hepatic or kidney disorders, which may benefit from CB1 antagonism [28]. The gene discussed is CNR1; the disease is obesity due to melanocortin 4 receptor deficiency.