* Contraindications: glucose-6-phosphate dehydrogenase (G6PD) deficiency, pregnancy, breastfeeding (if infant has G6PD deficiency or if G6PD status is unknown), known hypersensitivity to 8-aminoquinolines, history of psychiatric disorder. The gene discussed is G6PD; the disease is hyperinsulinemic hypoglycemia, familial, 4.