In Vivo Studies of Phenylalanine Hydroxylase by Phenylalanine Breath Test: Diagnosis of Tetrahydrobiopterin-Responsive Phenylalanine Hydroxylase Deficiency
نویسندگان
چکیده
منابع مشابه
Molecular genetics of tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency.
Mutations in the phenylalanine hydroxylase (PAH) gene result in phenylketonuria (PKU). Tetrahydrobiopterin (BH(4))-responsive hyperphenylalaninemia has been recently described as a variant of PAH deficiency caused by specific mutations in the PAH gene. It has been suggested that BH(4)-responsiveness may be predicted from the corresponding genotypes. Data from BH(4) loading tests indicated an in...
متن کاملWild-type phenylalanine hydroxylase activity is enhanced by tetrahydrobiopterin supplementation in vivo: an implication for therapeutic basis of tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency.
We previously proposed a novel disease entity, tetrahydrobiopterin (BH4)-responsive phenylalanine hydroxylase (PAH) deficiency, in which administration of BH4 reduced elevated levels of serum phenylalanine [J. Pediatr. 135 (1999) 375-378]. Subsequent reports indicate that the prevalence of BH4-responsive PAH deficiency is much higher than initially anticipated. Although growing attention surrou...
متن کاملTetrahydrobiopterin responsiveness of patients with phenylalanine hydroxylase deficiency.
OBJECTIVE To identify patients responsive to tetrahydrobiopterin (BH4) in a sample of Brazilians with hyperphenylalaninemia due to phenylalanine hydroxylase deficiency (HPA-PAH). METHODS Interventional study, convenience sampling. The inclusion criteria were: diagnosis of HPA-PAH; age ≥ 7 years; phenylalanine-restricted diet and phenylalanine (Phe) levels ≥ 6 mg/dL in all blood tests 1 year b...
متن کاملTetrahydrobiopterin protects phenylalanine hydroxylase activity in vivo: implications for tetrahydrobiopterin-responsive hyperphenylalaninemia.
The natural cofactor of phenylalanine hydroxylase (PAH), tetrahydrobiopterin (BH4), regulates the enzyme activity as well as being essential in catalysis. BH4-responsive PAH deficiency is a variant of hyperphenylalaninemia or phenylketonuria (PKU) caused by mutations in the human PAH gene that respond to oral BH4 loading by stimulating enzyme activity and therefore lowering serum phenylalanine....
متن کاملMechanism of phenylalanine regulation of phenylalanine hydroxylase.
The mechanism of phenylalanine regulation of rat liver phenylalanine hydroxylase was studied. We show that phenylalanine "activates" phenylalanine hydroxylase, converting it from an inactive to active form, by binding at a true allosteric regulatory site. One phenylalanine molecule binds per enzyme subunit; it remains at this site during catalytic turnover and, while there, cannot be hydroxylat...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Pediatric Research
سال: 2004
ISSN: 0031-3998,1530-0447
DOI: 10.1203/01.pdr.0000141520.06524.51