It has been recommended by recent guidelines and consensus statements from the European Thyroid Association (ETA) and the Japan Thyroid Association (JTA), respectively, that levothyroxine treatment in patients with coexistent RTHβ and AIH should either be titrated to achieve FT4 comparable to other family members with RTHβ alone, titrated to maintain high-normal TSH and high free TH concentrations, or to achieve symptomatic improvement [16, 17]. The gene discussed is TH; the disease is autoimmune hepatitis.