INS and obesity due to melanocortin 4 receptor deficiency: In vitro experiments carried out on myocytes from normal subjects and patients with obesity or T2D have demonstrated the ability of insulin to enhance BRS-3 expression (5), which may also be a possible mediator in the regulation of BRS-3 gene expression, as BRS-3 expression has been detected in cells expressing high levels of insulin receptor, such as fibroblasts, where certain regulatory processes are produced by the hormone (24,25).