MFN2 and obesity due to melanocortin 4 receptor deficiency: As part of the mitochondrial fusion machinery, mitofusin 1 and 2 (MFN1 and MFN2, respectively) were significantly increased by DPR, irrespective of obesity (Figure 4A,B), whereas optic atrophy 1 (OPA1) expression was unchanged (Figure 4A,B).