Background: Tirzepatide (Mounjaro) is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist increasingly prescribed for type 2 diabetes and obesity due to its efficacy in weight loss and glycaemic control. This evidence concerns the gene GLP1R and obesity due to melanocortin 4 receptor deficiency.