Obesity is thought to induce catecholamine resistance in adipose tissue by downregulating β-AR expression and interfering with downstream β-adrenergic signaling pathways, such as PKA activity (Reynisdottir et al., 1994; Arner, 1999; Jocken et al., 2008). The gene discussed is ADRB2; the disease is obesity due to melanocortin 4 receptor deficiency.