In newborns and infants hyperinsulinism can have many different causes: congenital hyperinsulinism (transient and persistent), maternal diabetes, insulin resistance syndromes, hyperinsulinism syndrome-related (such as Becwith-Wiedemann, Costello, Noonan and Leopard syndrome) and iatrogenic hyperinsulinism (excessive infusion of insulin) [1]. The gene discussed is INS; the disease is hyperinsulinism.