Landmark studies on cohorts of human Laron Syndrome (LS) patients with a non-functioning GHR, in Israel by Laron and colleagues[34,37,38] and in Ecuador by Jaime Guevara-Aguerra and colleagues[33,39,40], as well as on LS mouse models of GHR knock-out (GHRKO) produced in our laboratory[2,3,41,42] have established the beneficial effects of congenital resistance to GH action. Here, GHR is linked to Leigh syndrome.