To test our hypothesis, we used a novel mouse model of isolated endocrine IGF‐1 deficiency induced by adeno‐associated viral knockdown of IGF‐1 specifically in the mouse liver using Cre‐lox technology (Igf1f/f + TBG‐Cre‐AAV8; Toth et al., 2014, 2015a; Tarantini et al., 2016a,b). The gene discussed is IGF1; the disease is hyperinsulinemic hypoglycemia, familial, 4.