ABCG1 and obesity due to melanocortin 4 receptor deficiency: Taken together, these observations support the claim that lower methylation of the CPT1A and TXNIP loci and increased methylation of the ABCG1 locus associate with a well-defined diabetes-specific metabolic phenotype, which is mirrored by the association of the loci with the respective clinical phenotypes, obesity, and diabetes.