LEP and obesity due to melanocortin 4 receptor deficiency: On the other hand the expression levels of miR-34a remains constant in our leptin-deficient ob/ob mice as well as PPARγ-dominant negative HFD animals in comparison to the respective control group even though the degree of obesity in these animals is at least comparable to or in the case of ob/ob mice much higher than in the group of PPARγ-wt HFD mice.