PAX8 and thanatophoric dysplasia: At least 12 genes have been described that are involved in the pathogenesis of CH, part of which were shown to be involved in thyroid dysgenesis (TD) [4] (TSHR [5], PAX8 [6], NKX2-5 [7], FOXE1 [8], NKX2-1 [9,10]), while the others were linked to the defects in biosynthesis of thyroid hormones, i.e. dyshormonogenesis (DH) (TPO [11], IYD [12], SLC26A4 [13], TG [14], SLC5A5 [15], DUOX2 [16], DOUXA2 [17]) [18].