Therefore, they were all diagnosed as BH4 deficiency caused by PTPS deficiency, and a combined stress test was performed: 3 h after Phe loading, the blood Phe was (720–1200) μmol/L, and the blood Phe concentration decreased to (120–240) μmol/L 4–6 h after oral administration of BH4 tablets of 7.5 mg/kg. This evidence concerns the gene PTS and hyperinsulinemic hypoglycemia, familial, 4.