Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare autosomal recessive neurodevelopmental disorder that typically presents in infancy, and is characterized biochemically by deficiency of the catecholamines (dopamine, epinephrine, and norepinephrine) and serotonin1. The gene discussed is DDC; the disease is hyperinsulinemic hypoglycemia, familial, 4.