<prompt> Mutations in the developmental transcription factors or their downstream target genes are rare causes of thyroid agenesis or dyshormonogenesis. All are examples of thyroid transcription factors, EXCEPT:Thyroid transcription factor TTF-1TTF-2Paired homeobox-8 PAX-8Sodium iodide sympoer  <response>: Thyroid gland development is coordinated by the expression of several developmental transcription factors. Thyroid transcription factor TTF-1 TTF-2 Paired homeobox-8 PAX-8 are expressed selectively in the thyroid gland. They dictate thyroid cell development and the induction of thyroid-specific genes such as Thyroglobulin Tg Thyroid peroxidase TPO Sodium iodide sympoer NaI, NIS Thyroid-stimulating hormone receptor TSH-R. Sodium iodide sympoer NaI, NIS is a thyroid specific gene and not a transcription factor. Mutations in these developmental transcription factors or their downstream target genes are rare causes of thyroid agenesis or dyshormonogenesis. Ref: Harrison, E-18, P-2912 