Collectively, these data obtained in ≥100 Mexican patients suggest that germline small-nucleotide defects in the main TD-related genes, PAX8 [18], NKX2-1 [19], FOXE1, NKX2-5, and TSHR (this work), could explain ~2.5% of the isolated CH-TD cases in Mexico, without any identified etiologic role for CNVs in PAX8, NKX2-1, FOXE1, or TSHR (NKX2-5 was not included in the employed MLPA kit). This evidence concerns the gene PAX8 and thanatophoric dysplasia.