Tetrahydrobiopterin(BH4) deficiency is a rare type of hyperphenylalaninemia and usually leads to a progressive neurologic deterioration despite early dietary control of blood phenylalanine concentration. We experienced two cases of BH4 deficiency in brother and sister, confirmed by biochemical study of blood and urine. They had suffered from a progressive neurologic illness such as mental retardation, severe hypotonia, seizure, and athetotic movements started at 3 months of their age. Blood amino-acid analysis showed mild hyperphenylalaninemia with elevated urinary neopterin, and reduced urinary biopterin. Their neurologic deteriorations were dramatically improved after replacement of BH4 and dopamine agonist.
Biopterin ; Dopamine Agonists ; Humans ; Intellectual Disability ; Muscle Hypotonia ; Neopterin ; Phenylalanine ; Phenylketonurias* ; Seizures ; Siblings

OBJECTIVESTo assess the incidence of tetrahydrobiopterin (BH4) deficiency among patients with hyperphenylalaninemia (HPA) in southern Chinese and evaluate clinical outcome and gene mutations in tetrahydrobiopterin deficient patients.

METHODSUrinary neopterin (N) and biopterin (B) was analyzed in 87 patients with hyperphenylalaninemia by high-performance liquid chromatography. Further combined loading tests with phenylalanine (Phe) (100 mg/kg) and tetrahydrobiopterin (BH4) (7.5 mg/kg) were performed in suspected patients with abnormal urinary pterin profiles. Gene mutation analysis was performed for patients with BH4 deficiency and their parents. BH4 deficient patients were treated with BH4 and neurotransmitter precursors after diagnosis. Blood phenylalanine levels, clinical symptoms and mental development were followed up.

RESULTSEleven patients were diagnosed as having BH4 deficiency caused by 6-pyruvoyl tetrahydropterin synthase (PTPS) deficiency. The incidence of tetrahydrobiopterin (BH4) deficiency among patients with hyperphenylalaninemia (HPA) in southern Chinese was 10%. Combined loading tests with phenylalanine and oral BH4 were done in 4 of 11 patients and their phenylalanine levels were decreased to normal 4 - 6h after BH4 administration. Four different mutations (P87S, N52S, D96N and G144R) in the PTPS gene were detected in 5 families. Five PTPS-deficient patients were treated with synthetic BH4, neurotransmitter precursors (L-dopa plus carbidopa, and 5-hydroxytryptophan). They had satisfactory physical and mental development after treatment. One patient with partial PTPS deficiency had normal growth and mental development without treatment.

CONCLUSIONSOur results emphasize that screening for BH4 deficiency should be carried out in all patients with hyperphenylalaninemia in order to minimize the misdiagnosis. Patients with BH4 deficiency should be treated early with BH4 and a combination of neurotransmitter precursors.

Biopterin ; administration & dosage ; analogs & derivatives ; deficiency ; urine ; China ; DNA Mutational Analysis ; DNA, Complementary ; chemistry ; genetics ; Follow-Up Studies ; Genetic Testing ; Humans ; Mutation, Missense ; Neopterin ; urine ; Phenylketonurias ; blood ; enzymology ; genetics ; Phosphorus-Oxygen Lyases ; genetics ; metabolism

PURPOSE: To investigate the effects of dexamethasone (DEX) on the production of nitric oxide (NO) and its enzymatic synthetic pathway in cultured human trabecular meshwork (HTM) cells. METHODS: Primarily cultured HTM cells were exposed to 0, 10, 100, 1000 nM of DEX for 3 days. In addition, 100 micrometer sepiapterin, 100 micrometer ascorbic acid, and 10 micrometer methotrexate were co-exposed to DEX. The cellular survival and nitrite production rates were assessed by MTT assay and Griess assay, respectively. RESULTS: DEX did not significantly affect the survival of cultured HTM cells. DEX decreased the NO production in a dose-dependent manner. With co-exposure of DEX, ascorbic acid nullified the DEX-induced decrease of NO production. Sepiapterin and methotrexate did not affect DEX-induced decrease of NO production. CONCLUSIONS: DEX decreased NO production in HTM cells and the de novo pathway of tetrahydrobiopterin may be involved. This decrease may raise intraocular pressure by decreasing trabecular outflow.
Ascorbic Acid ; Biopterin ; Dexamethasone ; Humans ; Intraocular Pressure ; Methotrexate ; Nitric Oxide ; Pterins ; Trabecular Meshwork

PURPOSE: To investigate the effects of dexamethasone (DEX) on the production of nitric oxide (NO) and its enzymatic synthetic pathway in cultured human trabecular meshwork (HTM) cells. METHODS: Primarily cultured HTM cells were exposed to 0, 10, 100, 1000 nM of DEX for 3 days. In addition, 100 micrometer sepiapterin, 100 micrometer ascorbic acid, and 10 micrometer methotrexate were co-exposed to DEX. The cellular survival and nitrite production rates were assessed by MTT assay and Griess assay, respectively. RESULTS: DEX did not significantly affect the survival of cultured HTM cells. DEX decreased the NO production in a dose-dependent manner. With co-exposure of DEX, ascorbic acid nullified the DEX-induced decrease of NO production. Sepiapterin and methotrexate did not affect DEX-induced decrease of NO production. CONCLUSIONS: DEX decreased NO production in HTM cells and the de novo pathway of tetrahydrobiopterin may be involved. This decrease may raise intraocular pressure by decreasing trabecular outflow.
Ascorbic Acid ; Biopterin ; Dexamethasone ; Humans ; Intraocular Pressure ; Methotrexate ; Nitric Oxide ; Pterins ; Trabecular Meshwork

Animals ; Biopterin ; analogs & derivatives ; therapeutic use ; Genetic Therapy ; Humans ; Phenylalanine Ammonia-Lyase ; administration & dosage ; Phenylketonurias ; therapy

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

OBJECTIVETo investigate the development of differential diagnosis of tetrahydrobiopterin (BH4) deficiency among patients with hyperphenylalaninemia (HPA) in provinces or cities of China and to investigate the incidence of BH4 deficiency.

METHODSOf the thirteen hundreds and ninety-two patients with HPA received, the differential diagnosis for BH4 deficiency during 1993 - 2007 were enrolled in this study. Of which, 591 patients came from outpatient and 801 patients' samples from other provinces or cities were sent to author's laboratory to investigate the case number of differential diagnosis for BH4 deficiency in provinces or cities of China according to the data from both outpatient case histories and laboratory as to investigating the development of differential diagnosis in the whole country. To discuss the diagnostic criteria for BH4 deficiency was according to the results of urinary pterin analysis, determination of dihydropteridine reductase (DHPR) activity and the tetrahydrobiopterin loading test as well as to get the incidence of BH4 deficiency and find some provinces or cities with higher incidence of BH4 deficiency in China.

RESULTS(1) The number of HPA patients, who were performed by urinary pterin analysis and the determination of DHPR activity, were remarkably increased in last three years (2005 - 2007). The patient numbers of both urinary pterin analysis and DHPR activity determination were 217 and 198 respectively in 2005. And in 2007 they increased to 511 and 458, which was about 2.3 times than that in 2005. The patients came from 29 provinces or cities in 2007. (2) The urinary biopterin and biopterin percent were key marks for diagnosis of 6-pyruvoyl tetrahydropterin synthase (PTPS) deficiency. The less than 5% [(1.41 +/- 1.10)%] biopterin percent and very low biopterin level [(0.14 +/- 0.17) mmol/mol Cr] were found in 96.83% (61/63) patients with PTPS deficiency in this study. The blood phenylalanine level was remarkably decreased to normal range at 2 - 6 hours after BH4 loading test. The very low DHPR activity was a final diagnostic mark for DHPR deficiency. The very low DHPR activities of 0.27 nmol/(min x 5 mm disc) (6.11% - 7.00% of normal controls) were found in two patients with DHPR deficiency in this study. (3) The incidences of PTPS deficiency and DHPR deficiency among 1392 patients with hyperphenylalaninemia were 8.41% (117/1392) and 0.18% (2/1108) respectively. About 67.23% (80/119) patients with BH4 deficiency came from the south of Yangtze liver. The 80% (8/10) provinces or cities with higher incidence of BH4 deficiency are located in eastern and southern China. The incidence of PTPS deficiency among patients with HPA and normal newborns was 10.81% (8/74) and 0.007 per thousand (8/1,121,429) respectively in Shanghai, China according to data from neonatal screening.

CONCLUSIONThe awareness of differential diagnosis for BH4 deficiency from clinic pediatricians has been increased in most provinces or cities of China in last three years, but it should be more strengthened.

Biopterin ; analogs & derivatives ; deficiency ; China ; epidemiology ; Diagnosis, Differential ; Humans ; Incidence ; Infant, Newborn ; Neonatal Screening ; Phenylketonurias ; complications ; diagnosis ; epidemiology

BACKGROUNDA novel therapeutic strategy for phenylketonuria (PKU) has been initiated in Japan. Hyperphenylalaninemia (HPA) results from a phenylalanine hydroxylase (PAH) enzyme deficiency or a deficiency of its cofactor, tetrahydrobiopterin (BH4). BH4 can normalize blood phenylalanine levels in BH4 deficiency, but typically not in PKU. However, since 1999 it has been reported that many HPA patients (serum phenylalanine <20 mg/dL) showed a gradual decrease of serum phenylalanine levels after 24 hours from BH4 loading. The BH4 responsiveness seems to be regulated in mild PKU by PAH mutations, and affected by the BH4 dose and administration period.

METHODS AND RESULTSIn 2002 we formulated a provisional diagnostic criteria for patients with BH4-responsive PAH deficiency, and newly diagnosed 19 patients in 100 HPA cases between 2002 and 2006. The incidence in the recent 5 years for BH4-responsive mild PKU among patients with PAH deficiency was 25 %.

CONCLUSIONA total of 31 patients was detected in the past 10 years, and the incidence detected using the provisional diagnostic criteria had increased to 25% among PAH deficient patients. BH4 treatment for BH4-responsive mild PKU is a new and effective pharmacotherapy, which replaces or liberalises the phenylalanine-restricted diets for a considerable number of mild PKU patients.

Biopterin ; analogs & derivatives ; therapeutic use ; Humans ; Infant, Newborn ; Japan ; Phenylketonurias ; diagnosis ; drug therapy ; Severity of Illness Index ; Time Factors

BACKGROUND AND PURPOSE: PET scanning with fluorodeoxyglucose (FDG-PET) is a non-invasive method that measures regional glucose metabolic rate. Phenylalanine (Phe) and its metabolites appear to impair several aspects of brain energy metabolism. 1) To evaluate brain glucose metabolism with FDG-PET imaging in phenylketonuria (PKU) patients before and 4 months after sapropterin therapy; 2) to evaluate neurodevelopmental changes, blood Phe levels and dietary Phe tolerance before and after sapropterin therapy; 3) to generate pilot data to assess the feasibility of evaluating brain glucose metabolism with FDG-PET imaging and to explore potential trends resulting from the administration of sapropterin therapy. METHODS: We enrolled 5 subjects, ranged in age from 22 years to 51 years, with PKU. Subjects underwent FDG-PET brain imaging, blood tests for Phe and tyrosine levels, and neurocognitive evaluations before and 4 months after sapropterin therapy (20 mg/kg/day). All subjects' Phe and tyrosine levels were monitored once a week during the study. Subjects kept 3 day diet records that allow calculation of Phe intake. RESULTS: None of the subjects responded to sapropterin therapy based on 30% decrease in blood Phe level. The data show that glucose metabolism appeared depressed in the cerebellum and left parietal cortex while it was increased in the frontal and anterior cingulate cortices in all five subjects. In response to sapropterin therapy, relative glucose metabolism showed significant increases in left Broca's and right superior lateral temporal cortices. Interestingly, there was corresponding enhanced performance in a phonemic fluency test performed during pre- and postneurocognitive evaluation. CONCLUSIONS: Further studies with a larger sample size are needed to confirm the above changes in both sapropterin non-responsive and responsive PKU patients.
Biopterin ; Brain ; Cerebellum ; Diet Records ; Electrons ; Energy Metabolism ; Glucose ; Hematologic Tests ; Humans ; Neuroimaging ; Phenylalanine ; Phenylketonurias ; Pilot Projects ; Positron-Emission Tomography ; Sample Size ; Tyrosine

Oxidative damage is thought to be a major cause of the progression of dopamine (DA)rgic neurodegeneration as in Parkinson's disease. We have previously reported that tetrahydrobiopterin (BH4), an endogenous molecule required for DA synthesis, exerts oxidative stress to DA-producing cells and facilitates the production of DA quinone. It is known that aconitase, present in both mitochondrial and cytosolic forms, act as an reactive oxygen species (ROS) sensor, and that their inactivation leads to further generation of ROS. In the present study we investigated whether the BH4-associated vulnerability of DA cells might involve aconitase. In DArgic cell line CATH.a, BH4 treatment caused reduction of activity of both mitochondrial and cytosolic aconitases, and this appeared to be due to direct inactivation of the pre-existing enzyme molecules. Although most of the activity reduced by BH4 was increased upon reactivation reaction under a reducing condition, the restoration was not complete, suggesting that irreversible and covalent modification has occurred. The aconitase inactivation was exacerbated in the presence of DA and attenuated in the presence of tyrosine hydroxylase inhibitor a-methyl-p-tyrosine, suggesting the involvement of DA. The degree of inactivation increased when the cells were treated with the quinone reductase inhibitor dicoumarol and decreased in the presence of quinone reductase inducer sulforaphane. Taken together, BH4 appeared to lead to both reversible and irreversible inactivation of aconitase and that this is facilitated by the presence of DA and accumulation of DA quinone.
Aconitate Hydratase ; Benzoquinones ; Biopterin ; Cell Line ; Cytosol ; Dicumarol ; Dopamine ; NAD(P)H Dehydrogenase (Quinone) ; Oxidative Stress ; Parkinson Disease ; Reactive Oxygen Species ; Thiocyanates ; Tyrosine 3-Monooxygenase