BDNF and obesity due to melanocortin 4 receptor deficiency: Because the rs10767664 polymorphism had been strongly associated with obesity and was shown to occur within an enhancer of BP4 activity we expected to see a significant decrease of BDNF mRNA in hypothalamic tissues, where expression of BDNF is known to affect appetite [30, 31] as well as an increase in food intake and greater weight gain in these animals.