The European Society of Endocrinology Clinical Guideline on the Endocrine Work-up in Obesity, published in 2020, for example, suggests serum TSH assessment in all patients with obesity, not recommending routine assessment of fT3 because its levels in subjects with obesity depend on several factors which influence the peripheral conversion of thyroid hormones [92]. The gene discussed is TG; the disease is obesity due to melanocortin 4 receptor deficiency.