Tetrahydrobiopterin as an alternative treatment for mild phenylketonuria
- PMID: 12501224
- DOI: 10.1056/NEJMoa021654
Tetrahydrobiopterin as an alternative treatment for mild phenylketonuria
Abstract
Background: Hyperphenylalaninemia is a common inherited metabolic disease that is due to phenylalanine hydroxylase deficiency, and at least half the affected patients have mild clinical phenotypes. Treatment with a low-phenylalanine diet represents a substantial psychosocial burden, but alternative treatments have not been effective.
Methods: To explore the therapeutic efficacy of tetrahydrobiopterin, we performed a combined phenylalanine-tetrahydrobiopterin loading test and analyzed the in vivo rates of [13C]phenylalanine oxidation in 38 children with phenylalanine hydroxylase deficiency (age range, 1 day to 17 years). We assessed whether responsiveness to tetrahydrobiopterin was associated with specific genotypes, and we mapped mutations using a structural model of the phenylalanine hydroxylase monomer.
Results: In 27 (87 percent) of 31 patients with mild hyperphenylalaninemia (10 patients) or mild phenylketonuria (21 patients), tetrahydrobiopterin significantly lowered blood phenylalanine levels. Phenylalanine oxidation was significantly enhanced in 23 of these 31 patients (74 percent). Conversely, none of the seven patients with classic phenylketonuria had a response to tetrahydrobiopterin as defined in this study. Long-term treatment with tetrahydrobiopterin in five children increased daily phenylalanine tolerance, allowing them to discontinue their restricted diets. Seven mutations (P314S, Y417H, V177M, V245A, A300S, E390G, and IVS4-5C-->G) were classified as probably associated with responsiveness to tetrahydrobiopterin, and six mutations (A403V, F39L, D415N, S310Y, R158Q, and I65T) were classified as potentially associated. Four mutations (Y414C, L48S, R261Q, and I65V) were inconsistently associated with this phenotype. Mutations connected to tetrahydrobiopterin responsiveness were predominantly in the catalytic domain of the protein and were not directly involved in cofactor binding.
Conclusions: Tetrahydrobiopterin responsiveness is common in patients with mild hyperphenylalaninemia phenotypes. Responsiveness cannot consistently be predicted on the basis of genotype, particularly in compound heterozygotes.
Copyright 2002 Massachusetts Medical Society
Comment in
-
Tetrahydrobiopterin and dietary restriction in mild phenylketonuria.N Engl J Med. 2002 Dec 26;347(26):2094-5. doi: 10.1056/NEJMp020147. N Engl J Med. 2002. PMID: 12501220 No abstract available.
-
Tetrahydrobiopterin and mild phenylketonuria.N Engl J Med. 2003 Apr 24;348(17):1722-4; author reply 1722-4. doi: 10.1056/NEJM200304243481719. N Engl J Med. 2003. PMID: 12711753 No abstract available.
-
Tetrahydrobiopterin and mild phenylketonuria.N Engl J Med. 2003 Apr 24;348(17):1722-4; author reply 1722-4. N Engl J Med. 2003. PMID: 12715773 No abstract available.
-
Tetrahydrobiopterin and mild phenylketonuria.N Engl J Med. 2003 Apr 24;348(17):1722-4; author reply 1722-4. N Engl J Med. 2003. PMID: 12715774 No abstract available.
Similar articles
-
Molecular genetics of tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency.Hum Mutat. 2008 Jan;29(1):167-75. doi: 10.1002/humu.20637. Hum Mutat. 2008. PMID: 17935162
-
Incidence of BH4-responsiveness in phenylalanine-hydroxylase-deficient Italian patients.Mol Genet Metab. 2005 Dec;86 Suppl 1:S67-74. doi: 10.1016/j.ymgme.2005.06.017. Epub 2005 Sep 28. Mol Genet Metab. 2005. PMID: 16198137
-
Potential role of tetrahydrobiopterin in the treatment of maternal phenylketonuria.Pediatrics. 2003 Dec;112(6 Pt 2):1566-9. Pediatrics. 2003. PMID: 14654666
-
Tetrahydrobiopterin, its mode of action on phenylalanine hydroxylase, and importance of genotypes for pharmacological therapy of phenylketonuria.Hum Mutat. 2013 Jul;34(7):927-36. doi: 10.1002/humu.22320. Epub 2013 May 1. Hum Mutat. 2013. PMID: 23559577 Review.
-
The metabolic and molecular bases of tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency.Mol Genet Metab. 2004 Jun;82(2):101-11. doi: 10.1016/j.ymgme.2004.03.006. Mol Genet Metab. 2004. PMID: 15171997 Review.
Cited by
-
Biopterin metabolism and nitric oxide recoupling in cancer.Front Oncol. 2024 Feb 26;13:1321326. doi: 10.3389/fonc.2023.1321326. eCollection 2023. Front Oncol. 2024. PMID: 38469569 Free PMC article. Review.
-
Maximal dietary responsiveness after tetrahydrobiopterin (BH4) in 19 phenylalanine hydroxylase deficiency patients: What super-responders can expect.Mol Genet Metab Rep. 2024 Jan 12;38:101050. doi: 10.1016/j.ymgmr.2024.101050. eCollection 2024 Mar. Mol Genet Metab Rep. 2024. PMID: 38469087 Free PMC article.
-
Neurotransmitters Disorders with Mild Hyperphenylalaninemia: The Ones That Should Not Be Missed.Arch Razi Inst. 2023 Apr 30;78(2):667-673. doi: 10.22092/ARI.2022.359480.2431. eCollection 2023 Apr. Arch Razi Inst. 2023. PMID: 37396747 Free PMC article.
-
Expert opinion of an Italian working group on the assessment of cognitive, psychological, and neurological outcomes in pediatric, adolescent, and adult patients with phenylketonuria.Orphanet J Rare Dis. 2022 Dec 21;17(1):443. doi: 10.1186/s13023-022-02488-2. Orphanet J Rare Dis. 2022. PMID: 36544165 Free PMC article.
-
Serum glial fibrillary acidic protein and neurofilament light chain in patients with early treated phenylketonuria.Front Neurol. 2022 Sep 29;13:1011470. doi: 10.3389/fneur.2022.1011470. eCollection 2022. Front Neurol. 2022. PMID: 36247773 Free PMC article.
Publication types
MeSH terms
Substances
LinkOut - more resources
Full Text Sources
Other Literature Sources
Medical
Molecular Biology Databases