Obesity trials conducted with different MC4R agonists have, for example, reported cardiovascular disorders, gastrointestinal disorders (i.e., nausea and vomiting), erectile function disorders (penile erection) or skin hyperpigmentation with different administrations (i.e., oral and subcutaneous) [58]. The gene discussed is MC4R; the disease is obesity due to melanocortin 4 receptor deficiency.