We have also demonstrated the occurrence of transgenerational epigenetic effects by thyroid hormones using a mouse model of genetic deficiency in the type 3 deiodinase (DIO3), the enzyme that clears both thyroid hormones (26), thyroxine (T4), and 3,5,3’-triiodothyronine (T3), which is considered the active hormone and responsible for canonical signaling due to its highest affinity for the nuclear thyroid hormone receptor (27, 28). This evidence concerns the gene TG and hyperinsulinemic hypoglycemia, familial, 4.