2001). However, several models of TH deficiency, including the Dio3−/− model, exhibit growth retardation in the embryonic and early post-natal period (Gothe et al. 1999, Hernandez et al. 2006) when growth and IGF1 secretion are known to be GH independent (Lupu et al. 2001). The gene discussed is DIO3; the disease is hyperinsulinemic hypoglycemia, familial, 4.