Based on the results of biochemical tests, including measuring the Phe and tyrosine levels in the blood, urinary pterins (neopterin and biopterin), and DHPR enzyme activity on DBS, it was found that four patients have DHPR deficiency and six other patients have PTPS deficiency (Table 2). Here, QDPR is linked to hyperinsulinemic hypoglycemia, familial, 4.