MCT8 dysfunction, as a prerequisite of AHDS, is supported by limited pre-clinical data from mouse models and clinical trials in AHDS patients and when treated with the TH analog 3,5-diiodothyropropionic acid (DITPA) resulted in amelioration of peripheral hyperthyroidism and overall hypermetabolism (Verge et al., 2012; Ferrara et al., 2015). Here, TH is linked to Allan-Herndon-Dudley syndrome.