Table 1.

Inheritable Forms of Impaired Sensitivity to Thyroid Hormone

Abbreviations: FT₃, free T₃; FT₄, free T₄; BMI, body mass index.

^aProposed future terminology: RTH beta.

^bRTH without mutations in the THRB gene.

^cA single case with a mutation involving both TRα1 and TRα2 presented a more complex phenotype, including severe bone malformations, hypercalcemia with hyperparathyroidism, and diarrhea rather than constipation. It is unclear whether all observed abnormalities are due to the THRA gene mutation alone.