SIRT1 and obesity due to melanocortin 4 receptor deficiency: In contrast, we found no association between CpG methylation status of the SIRT1 and SIRT7 regulatory regions and their expression on the mRNA level in adipose tissues, so it is possible that methylation does not play a crucial role in obesity-associated changes in SIRTs expression in humans (Kurylowicz A, unpublished).