For instance, a loss of Grf1 or Dlk1 resulted in reduced GH content and secretion [67,68], while disruption of the imprinting domain encompassing Dlk1, Rtl1, and Dio3 resulted in transient perturbation in the GH/IGF-1 growth pathway with hypothyroidism [69]. Here, DLK1 is linked to hypothyroidism.