There was 63.3% mortality in RFXANK deficiency (median 16 months), 24.7% in RAG1 deficiency (median 22 months), 25.6% in IL2RG deficiency (median 12.5 months), 21.4% in ITGB2 deficiency (median 11 months), and 10.9% in CYBB deficiency (median 183 months). The gene discussed is CYBB; the disease is hyperinsulinemic hypoglycemia, familial, 4.