Molecular mechanisms underlying the effectiveness of triiodothyroacetic acid (Triac) in patients with resistance to thyroid hormone β (RTHβ): a multicentre, international, retrospective cohort study

Summary: Background: Disease features in resistance to thyroid hormone beta (RTHβ), caused by THRB mutations, arise from insensitivity to thyroid hormone in tissues expressing thyroid hormone receptor (TR)β and from lifelong thyrotoxic effects in TRα1-expressing tissues, posing substantial cardiovascular morbidity/mortality. The T3-analogue triiodothyroacetic acid (Triac) holds potential as an effective treatment. Systematic data on Triac therapy in RTHβ are lacking, and the mechanisms through which Triac acts are unclear. This study aims to elucidate these knowledge gaps.