Whereas GH insensitivity, both in humans and in transgenic mice, have only mild retardation of growth at birth as previously stated[31-35], IGF-I deficiency in gestational state reveals serious postnatal growth retardation, as has been reported both in humans and in transgenic animal models of IGF-I deletion[36-40]. The gene discussed is IGF1; the disease is hyperinsulinemic hypoglycemia, familial, 4.