GHR and Severe short stature: Ames and Snell dwarf mice [14],[15], GH releasing hormone (GHRH) defective little mice (Ghrhrlit/lit) [16], GH receptor/binding protein null mice (Ghr/bp−/−) [17] and IGF1 receptor heterozygous mice (Igf1r+/−) [18] all show suppressed GH/IGF1 signaling, dwarfism and a significantly increased lifespan compared to wild type (wt) control mice.