Therefore, genetic testing of the candidate genes THRB and SLC16A2 should be performed for diagnosis of RTH and AHDS in patients with the suggestive clinical phenotype.
In particular, the application of 3,3',5-triiodothyroacetic acid (Triac) in RTH due to defective TRβ and the role of 3,5-diiodothyropropionic acid (DITPA), 3,3',5,5'-tetraiodothyroacetic acid (Tetrac) and Triac in MCT8 deficiency will be highlighted.
1) When thyroid hormone production was reduced by PTU, high doses of LT(4) (3.7 microg/kg.d) were needed to normalize serum TSH, confirming that mutation of MCT8 is a cause of resistance to thyroid hormone.
Mutational analysis of the MCT8 gene revealed mutations or deletions in the MCT8 gene in unrelated male patients with severe psychomotor retardation and biochemical findings consistent with thyroid hormone resistance.