POMC and obesity due to melanocortin 4 receptor deficiency: Reprogramming of DNA methylation in PPARGC1A (the gene encoding PGC1, a master regulator of biogenesis and mitochondrial function) has also been shown in subjects with obesity of all ages, as well as hypermethylation of the proopiomelanocortin (POMC) promoter of intron 2/exon 3 in the melanocortin system.