Importantly, DNA methylation analysis, from PBMCs isolated from the prepubertal children with obesity, showed hypermethylation of different CpGs that are localized in the vicinity of important metabolic genes, including PEMT, MTRR, and MTHFR, suggesting that an epigenetic effect could be the cause for this downregulation. Here, MTRR is linked to obesity due to melanocortin 4 receptor deficiency.