Only one previous study by Muniandy et al. used adipose tissue (subcutaneous) to study clinical changes associated with obesity; The study found that the heavier twin in BMI-discordant monozygotic twin pairs displayed an upregulation of inflammation and other immunological pathways/genes (e.g. IFI30 and CCL18) [32]. Here, CCL18 is linked to obesity due to melanocortin 4 receptor deficiency.