title: Sapropterin is safe and effective in patients less than 4-years-old with BH4-responsive phenylalanine hydrolase deficiency.
abstract: OBJECTIVE
  To assess the safety and efficacy of tetrahydrobiopterin therapy with sapropterin to treat tetrahydrobiopterin (BH4)-responsive phenylalanine hydroxylase (PAH) deficiency in children aged <4 years compared with those aged ≥4 years.
  
  
  METHODS
  We analyzed a longitudinal follow-up study conducted in all patients with BH4-responsive PAH deficiency throughout Japan. At the end of 2011, 43 patients were receiving sapropterin, of whom 21 were aged <4 years at the initiation of treatment. The starting dose of sapropterin was ≥10 mg/kg/day in 11 of these 21 patients. The duration of follow-up was ≥4 years in 6 of those 11 patients; 3 of these 6 were followed for ≥10 years. Nine patients were receiving sapropterin monotherapy at the end of 2011.
  
  
  RESULTS
  Serum phenylalanine level was maintained within the recommended optimal control range in all 21 patients who started sapropterin treatment before age 4 years. Only 1 nonserious adverse drug reaction occurred, an elevated alanine aminotransferase level in 1 patient. No significant abnormal behavior related to nerve disorders was reported.
  
  
  CONCLUSIONS
  Sapropterin therapy initiated before age 4 years was effective in maintaining serum phenylalanine level within the favorable range and was safe in Japanese patients with BH4-responsive PAH deficiency.
authors.affiliation: Department of Pediatrics, Osaka City University School of Medicine, Osaka, Japan. Electronic address: shintakuh@med.osaka-cu.ac.jp.
authors.forename: Haruo
authors.initials: H
authors.lastname: Shintaku
authors.affiliation: Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ohura
mesh_terms: D000293:Adolescent; D001708:Biopterins / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D019001:Nitric Oxide Synthase / Q000009:adverse effects / Q000627:therapeutic use*; D010661:Phenylketonurias / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D001708:Biopterins; D019001:Nitric Oxide Synthase; C003402:sapropterin