A patient with Allan-Herndon-Dudley Syndrome has a number of problems related to thyroid hormone. This is related to dysfunction of the MCT8 (SLC16A2) gene which affects transport of thyroid hormone into cells.


A patient with Allan-Herndon-Dudley Syndrome has:

(1 ) elevated serum T3 concentration

(2) low or normal serum T4 concentration

(3) normal or high TSH concentration


The elevated serum T3 may be associated with:

(1) tachycardia

(2) weight loss


The T3 analogue Triac (triiodothyroacetic acid) does not require the MCT8 transporter to enter cells. Therapy with Triac in clinical trials is associated with:

(1) decrease in serum T3 concentration

(2) decrease in heart rate

(3) weight gain

(4) other functional improvements


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