POLG and obesity due to melanocortin 4 receptor deficiency: Our data are consistent with recent observation in C. elegans, where ATF5 homologs, ATFS‐1, can promote defective mtDNA expansion, leading to the accumulation of defective mitochondria.[14, 17] These data support the critical role of ATF5‐POLG axis potentially in promoting mutated mtDNA accumulation due to obesity.