Consensus ; Humans ; Nutritional Requirements ; Phenylalanine ; blood ; Phenylalanine Hydroxylase ; deficiency ; Phenylketonurias ; diagnosis ; diet therapy ; genetics ; Practice Guidelines as Topic

OBJECTIVETetrahydrobiopterin (BH(4)) responsive phenylalanine hydroxylase (PAH) deficiency is one of the forms of phenylketonuria (PKU). The aim of this study was to screen and diagnose BH(4) responsive PAH deficiency, to further understand its clinical characteristics, and to provide evidence for applying BH(4) drug therapy.

METHODSBH(4) 20 mg/kg loading test was performed in 73 patients with hyperphenylalaninemia (HPA) (47 males and 26 females), the mean age was 1.93 months. Combined phenylalanine (100 mg/kg) and BH(4) loading test was performed if patients had a basic blood phenylalanine concentration less than 600 micromol/L. The urine pterin profile analysis and the dihydropteridine reductase (DHPR) activity in dry blood filter spot were analyzed simultaneously. The patients with BH(4) responsive PAH deficiency were treated with BH(4) tablets (10 - 20 mg/kg x d) under normal diet for 6 to 7 days. Their blood phenylalanine concentration was checked.

RESULTS(1) The characteristic curve of phenylalanine level was observed in 73 patients after BH(4) loading test. Twenty-two patients were diagnosed as classic phenylketonuria (PKU), 39 were moderate PKU and 12 were BH(4) deficiency. (2) Twenty-two (56.4%) of 39 moderate PKU patients were found to be responsive to BH(4) and the blood phenylalanine was decreased by at least 30%. (3) Six patients with BH(4) responsive PAH deficiency were treated with BH(4) for 6 to 7 days, 4 patients had a normal phenylalanine concentration after 10 mg/kg BH(4) supplement, while other 2 patients needed a treatment of BH(4) at 20 mg/kg.

CONCLUSIONSome patients with moderate PKU caused by phenylalanine hydroxylase deficiency were responsive to BH(4). Their blood phenylalanine significantly decreased after oral BH(4) loading. The BH(4) loading test is an effective diagnostic method to detect BH(4) sensitivity in PKU patients. BH(4) responsive PAH deficiency patient could be treated with BH(4) to replace low-phenylalanine diet treatment totally or partially, which may provide an optional treatment for the disease and improve the quality of life of the patients.

Biopterin ; analogs & derivatives ; deficiency ; therapeutic use ; Child, Preschool ; Female ; Humans ; Infant ; Male ; Phenylalanine Hydroxylase ; deficiency ; Phenylketonurias ; diagnosis ; drug therapy

Phenylketonuria (PKU), an autosomal recessive disorder, occurs in one of 53,000 births in Korea. The disorder is associated with deficient activity of phenylalanine hydroxylase. In PKU, phenylalanine cannot be used in a normal fashion because of the deficient enzyme. Untreated, affected individuals develop marked mental disabilities, behavioral difficulties, seizures, rashes, pigment dilution, and unusual body odor. PKU treatment consists of a phenylalanine-restricted diet supplemented with a phenylalanine-free mixture of amino acids. During the restricted diet, PKU patients have an increased risk of developing vitamin B12 deficiency because of a limited intake of animal products. We report a successful anesthetic management in a patient with phenylketonuria for dental procedures.
Amino Acids ; Anesthesia, General* ; Animals ; Diet ; Exanthema ; Humans ; Korea ; Nitrous Oxide ; Odors ; Outpatients* ; Parturition ; Phenylalanine ; Phenylalanine Hydroxylase ; Phenylketonurias* ; Seizures ; Vitamin B 12 ; Vitamin B 12 Deficiency

Biopterin ; analogs & derivatives ; deficiency ; genetics ; Child ; Consensus ; Diagnosis, Differential ; Humans ; Infant ; Infant, Newborn ; Neonatal Screening ; methods ; Phenylalanine ; blood ; Phenylalanine Hydroxylase ; deficiency ; genetics ; Phenylketonurias ; classification ; diagnosis ; therapy ; Practice Guidelines as Topic ; Severity of Illness Index ; Tyrosine ; blood

Biopterin ; analogs & derivatives ; deficiency ; genetics ; Child ; Consensus ; Diagnosis, Differential ; Humans ; Infant ; Infant, Newborn ; Neonatal Screening ; Phenylalanine ; blood ; Phenylalanine Hydroxylase ; deficiency ; genetics ; Phenylketonurias ; diagnosis ; etiology ; therapy ; Practice Guidelines as Topic ; Societies, Medical

OBJECTIVETo perform tetrahydrobiopterin (BH(4)) loading test and to further understand its usefulness in differential diagnosis among hyperphenylalaninemia(HPA) patients.

METHODSBH(4) loading test was carried out in 73 HPA patients, including the positive cases unveiled by neonatal screening and the clinically suspected cases. These patients, 47 males and 26 females, were at a mean age of 1.93 months. BH(4) (20 mg/kg) loading test was performed in all patients, and a combined phenylalanine (Phe)(100 mg/kg) and BH(4) loading test was performed among the patient who had a basic blood Phe concentration less than 600 micro mol/L. The urine pterine profile analysis and the dihydropteridine reductase activity in dry blood filter spot were tested simultaneously.

RESULTSDuring BH(4) loading test or combined Phe and BH(4) loading test, the patients with classic phenylketonuria showed no response to BH(4), the patients with moderate HPA caused by Phe hydroxylase deficiency decreased 32.8% of blood Phe level and the patients with BH(4) deficiency showed a prompt reduction in blood Phe level and it decreased to normal level at 4 h and lasted until 24 h. Twenty-two cases were diagnosed as classic phenylketonuria, 39 were moderate phenylketonuria and 12 were BH(4) deficiency.

CONCLUSIONHyperphenylalaninemia may be caused by deficiency of Phe hydroxylase or by deficiency of co-factor BH(4). Early diagnosis is important. BH(4) loading test is a safe and fast test in vivo. It is sensitive, easy-to-do, and is highly useful in differential diagnosis for suspected cases of HPA.

Biopterin ; analogs & derivatives ; blood ; Diagnosis, Differential ; Dihydropteridine Reductase ; blood ; Female ; Humans ; Infant ; Infant, Newborn ; Male ; Mass Screening ; methods ; Phenylalanine ; blood ; Phenylalanine Hydroxylase ; deficiency ; genetics ; Phenylketonurias ; blood ; diagnosis ; genetics ; Sensitivity and Specificity

Phenylketonuria is an autosomal recessive disorder caused by a deficiency of phenylalanine hydroxylase. Transthyretin has been implicated as an indicator of nutritional status in phenylketonuria patients. In this study, we report that phenylalanine and its metabolite, phenylpyruvic acid, affect MAPK, changing transthyretin expression in a cell- and tissue-specific manner. Treatment of HepG2 cells with phenylalanine or phenylpyruvic acid decreased transcription of the TTR gene and decreased the transcriptional activity of the TTR promoter site, which was partly mediated through HNF4alpha. Decreased levels of p38 MAPK were detected in the liver of phenylketonuria-affected mice compared with wild-type mice. In contrast, treatment with phenylalanine increased transthyretin expression and induced ERK1/2 activation in PC-12 cells; ERK1/2 activation was also elevated in the brainstem of phenylketonuria-affected mice. These findings may explain between-tissue differences in gene expression, including Ttr gene expression, in the phenylketonuria mouse model.
Animals ; Brain Stem/metabolism/pathology ; Disease Models, Animal ; Gene Expression Regulation ; Hep G2 Cells ; Hepatocyte Nuclear Factor 4/metabolism ; Humans ; Liver/*metabolism/pathology ; Mice ; Mice, Mutant Strains ; Mitogen-Activated Protein Kinase 3/genetics/*metabolism ; Organ Specificity ; Phenylalanine/metabolism ; Phenylalanine Hydroxylase/deficiency ; Phenylketonurias/*genetics/metabolism/pathology/physiopathology ; Phenylpyruvic Acids/metabolism ; Prealbumin/*biosynthesis/genetics ; p38 Mitogen-Activated Protein Kinases/genetics/*metabolism