Abstract
BACKGROUND: The cases of obesity worldwide have increased significantly, with this condition being considered a global pandemic. This pathology poses a major health problem due to its high morbidity burden. Its cause in the majority of cases is multifactorial; however, there are various cases of monogenic obesity reported in the literature. Mutation in the leptin gene causes a marked decrease in leptin levels, leading to intense hyperphagia and associated morbid obesity. Substituting leptin with metreleptin is a treatment option for these patients. CASE PRESENTATION: We present the case of a patient with morbid obesity due to a single mutation in the LEP gene and approximately four years of treatment with metreleptin as a substitute therapy. Weight decreased from 154 to 64 kg and BMI decreased from 68.4 to 28.4 kg/m(2). CONCLUSIONS: The patient achieved a reduction of 40 kg/m2 in BMI, corresponding to a body weight loss of 90 kg, with a significant improvement in associated metabolic comorbidities, acne, and hirsutism.