In thalassemia major, the prevalence of low serum IGF-1 was much higher than that of the GH deficiency.38,39 The IGF-I response and the linear growth after exogenous administration of GH were less than that seen in GH deficient children treated with GH.39,40 These data suggest that thalassemic patients had some degree of GH insensitivity. The gene discussed is IGF1; the disease is thalassemia.