Progressive goiter, normal TSH, and raised circulating FT3 or an elevated T3/T4 ratio has been reported in the context of mild, dyshormonogenic CH due to partial, loss of function mutations in thyroid peroxidase (50) or thyroglobulin gene defects, with hypersecretion of T3 being attributed to increased thyroidal activity of pituitary type 2 deiodinase (51, 52). This evidence concerns the gene TG and goiter.