Since macrophages have been proposed as one of the major source of IGF-1 [36] and the functional interference with IGF-1 is known to influence the characteristics of the inflammatory response in skeletal muscle [37,38], we raise the possibility that the observed altered response to muscular injury and the IGF-1 deficiency might be causally related. This evidence concerns the gene IGF1 and hyperinsulinemic hypoglycemia, familial, 4.