PPARGC1A and obesity due to melanocortin 4 receptor deficiency: Contrary to its name, PGC-1α is not only a PPARγ coactivator, but also other transcription factors that are involved in the control of the expression of numerous key genes, not only in terms of mitochondrial biogenesis or angiogenesis, but also in terms of adipose tissue metabolism and the potential risk of developing obesity.