Indeed, in HAAF, recent antecedent iatrogenic hypoglycemia causes defective glucose counterregulation (reduced epinephrine response to falling glucose levels in the setting of an absent glucagon response) and hypoglycemia unawareness (decreased autonomic and related neurogenic symptom responses), thus creating and perpetuating a vicious cycle of recurrent hypoglycemia (2, 18, 19). The gene discussed is GCG; the disease is Hypoglycemia.