MFN2 and obesity due to melanocortin 4 receptor deficiency: Furthermore, we noted that obesity-induced alteration in mitochondrial dynamics pathways with increased mitochondrial fission as indicated by significant over-expression of the fission protein Drp1 accompanied by a decreased mitochondrial fusion as indicated by the substantial reduction in expression of fusion protein Mfn2 with the subsequent imbalance between mitochondrial fusion and fission.