Although the Mexican population has one of the highest worldwide CH birth prevalences, our results along with the previously published findings confirm that small nucleotide and clinically relevant germline variants in the main TD-related genes of PAX8 [18], NKX2-1 [19], FOXE1, NKX2-5, and TSHR account for a minority (2.5%) of primary and permanent CH Mexican patients due to non-syndromic TD. The gene discussed is PAX8; the disease is thanatophoric dysplasia.