B Dear Editor: b The clinical implications of inactivating mutations of the I THRB i gene are well known with the development of the syndrome of resistance to thyroid hormone beta (RTH ). Future studies should aim at correlating RTH pregnancy outcomes with maternal serum fT3 levels to clarify the clinical relevance of the observed elevated fT3 levels in AfMo carrying a NlFe. Notably, during the first 8-16 weeks of AfMo pregnancies, fT3 values increased to 174% ULN and 191% ULN when carrying a NlFe and AfFe, respectively. No significant differences were observed in the TSH values of RTH pregnancies carrying a NlFe compared to AfFe (Fig. [Extracted from the article]