Tirzepatide is a once‐weekly, dual glucose‐dependent insulinotropic polypeptide (GIP) and GLP‐1 receptor agonist that has demonstrated dose‐dependent efficacy in people with obesity, T2D or both, in terms of glycaemic control and bodyweight reduction in clinical trials. The gene discussed is GIP; the disease is obesity due to melanocortin 4 receptor deficiency.