Resistance to thyroid hormone is a rare genetic condition caused by germline mutations of the thyroid hormone receptor gene. The precise incidence is unknown
sporadic or de novo mutations are found. The mutant receptor results in an impaired thyroid hormone function. Thyroid hormone receptor beta gene (THRB) mutations and alpha gene (THRA) mutations are the main sites of mutation. Clinical features vary
they can show features of hyperthyroidism, hypothyroidism, or a combination of both. Even different tissues in the same individual may have different effects. Diagnosis is confirmed by genetic testing. The treatment is based on symptoms. Here we describe a case of thyroid hormone resistance, whose case was confirmed with genetic analysis, with a mutation in the THR gene, not found on online databases.