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Table 1 Justification and benefits of the neonatal BH4 loading test

From: Diagnostic and therapeutic recommendations for the treatment of hyperphenylalaninemia in patients 0–4 years of age

  Criteria/benefit of the neonatal BH4 loading test
1 BH4 treatment is now available from birth in Europe (as well as USA)
2 The Phe concentration in the newborn with a genetic defect in phenylalanine metabolism is spontaneously evaluated
3 The neonatal test allows the early diagnosis of GTPCH or PTPS deficiency
4 The normalization of blood Phe concentration will be reached sooner in the responsive neonates
5 The 24-h test only delays the management of the condition by 24 h and allows treatment to begin within the first 10 days of life
6 A complete phenotype of the patient is generated (Phe level and BH4 responsiveness)
7 The parents are rapidly informed of the types of treatment that are available for their child
8 Some patients will be able to avoid the dietetic treatment from birth
9 The good safety profile of this molecule is well established
10 The neonatal test avoids performing a Phe load in young patients after the newborn period
  1. BH4 Tetrahydrobiopterin, GTPCH Guanosine triphosphate cyclohydrolase I, Phe Phenylalanine, PTPS 6-pyruvoyl-tetrahydropterin synthase