“…Earlier literature reported that mutations in several genes such as the sodium iodide symporter [1,2], thyroglobulin [3,4], pendrin [5,6], dual oxidase 2 [7,8], dual oxidase maturation factor 1 [9], dual oxidase maturation factor 2 [7,9], TPO [10,11] are involved in the disruption of thyroid hormone biosynthesis. Among these genes, mutations of the TPO gene, which causes a total iodide organification defect (TIOD), was reported to be the most severe and common condition [12].…”