However, it should be noted that impairment of expression of mitochondria-related genes does not necessarily lead to obesity as documented by manipulations with mitochondrial transcription factor A (TFAM), one of the major controllers of mitochondrial mass: in mice deficient in TFAM in adipocytes, activity of proteins in respiratory complexes I, III, and IV was severely compromised, which resulted in adipocyte death and inflammation in WAT and whitening of BAT [88]. This evidence concerns the gene TFAM and obesity due to melanocortin 4 receptor deficiency.