IYD and dermatitis herpetiformis, familial: Most cases of DH are due to mutations in TG, TPO, SLC5A5/NIS, SLC26A4/PDS, IYD/DEHAL1, DUOX2, DUOXA2, DUOX1, DUOXA1, and SLC26A7, which are involved in thyroid hormone production and usually inherited on an autosomal recessive basis (4–6).