Characteristics of gene variants among patients with hyperphenylalaninemia from Quanzhou region of Fujian province / 中华医学遗传学杂志

OBJECTIVE@#To explore the spectrum of genetic variants among patients with hyperphenylalaninemia (HPA) from Quanzhou area of Fujian province.@*METHODS@#For 63 children affected with HPA, next generation sequencing was used to identify potential variants in PAH, PTS, PCBD1, QDPR, SPR and GCH1 genes.@*RESULTS@#Fifty two variants underlying phenylalanine hydroxylase deficiency (PAHD) and 13 variants underlying 6-pyruvoyl tetrahydropterin synthase deficiency (PTPSD) were identified. Two patients carried variants of both PAH and PTS genes. The most common variants of the PAH gene were R53H (21.69%), R241C(18.07%), R243Q(12.05%) and EX6-96A to G (7.23%), which were mainly located in exons 7 (32.53%), 2 (21.69%), 6 (9.64%) and 12 (9.64%). The L227M variant of the PAH gene was unreported previously. N52S (35.00%), P87S (25.00%), IVS1-291A to G (10.00%) and T67M (10.00%) variants were the most common variants for the PTS gene and were mainly located in exons 2 (35.00%) and 5 (35.00%).@*CONCLUSION@#The variant spectrum underlying HPA in Quanzhou area showed a geographical specificity. A novel variant of the PAH gene (L227M) has been detected.

BH4 deficiency identified in a neonatal screening program for hyperphenylalaninemia / Deficiências de BH4identificadas em um programa de triagem neonatal para hiperfenilalaninemias

Abstract Objectives To show the general prevalence and to characterize tetrahydrobiopterin (BH4) deficiencies with hyperphenylalaninemia, identified by the Neonatal Screening Program of the State of Minas Gerais. Methods Descriptive study of patients with BH4 deficiency identified by the Neonatal Screening Program of the State of Minas Gerais. Results The prevalence found was 2.1 for 1,000,000 live births, with a frequency of 1.71% among hyperphenylalaninemias. There were four cases (40%) with 6-pyruvoyl-tetrahydropterin synthase deficiency, three with GTP cyclohydrolase I - autosomal recessive form deficiency, and three with dihydropteridine reductase deficiency (30% each). Six patients were diagnosed due to clinical suspicion and four cases due to systematic screening in neonatal screening. After the start of the treatment, patients identified by neonatal screening had rapid improvement and improved neuropsychomotor development compared to those diagnosed by the medical history. Conclusions The prevalence of BH4 deficiencies in Minas Gerais was slightly higher than that found in the literature, but the frequency among hyperphenylalaninemias was similar. Although rare, they are severe diseases and, if left untreated, lead to developmental delays, abnormal movements, seizures, and premature death. Early treatment onset (starting before 5 months of age) showed good results in preventing intellectual disability, justifying the screening of these deficiencies in newborns with hyperphenylalaninemia identified at the neonatal screening programs for phenylketonuria.

Resumo Objetivos Apresentar a prevalência geral e caracterizar as deficiências de tetrahidrobiopterina - BH4 - com hiperfenilalaninemia, identificadas pelo Programa de Triagem Neonatal do Estadode Minas Gerais. Métodos Estudo descritivo de pacientes com deficiência de BH4 do Programa de Triagem Neonatal do Estado de Minas Gerais. Resultados A prevalência encontrada foi de 2,1 para 1.000.000 recém-nascidos vivos e a frequência de 1,71%, dentre as hiperfenilalaninemias. Quatro casos (40%) com deficiência de 6-piruvoil-tetrahidropterina sintase, três com deficiência de GTP ciclohidrolase I e três com deficiência de dihidropteridina redutase (30% cada um). Seis pacientes foram diagnosticadospor suspeita clínica e quatro pela pesquisa sistemática na triagem neonatal. Após o início do tratamento, os pacientes identificados pela triagem neonatal tiveram melhora rápida e melhor desenvolvimento neuropsicomotor em comparação com aqueles diagnosticados pela história clínica. Conclusões A prevalência das deficiências de BH4 em Minas Gerais foi um pouco maior que a encontrada na literatura, mas a frequência, entre as hiperfenilalaninemias, foi semelhante. Embora raras, são graves e, se não tratadas, levam a atraso de desenvolvimento, movimentos anormais, convulsões e morte precoce. O tratamento precoce (início antes dos 5 meses) mostrou bons resultados na prevenção de deficiência intelectual, justificando a pesquisa dessas deficiências nos recém-nascidos com hiperfenilalaninemia pelos programas de triagem neonatalpara fenilcetonúria.

Bioinformation analysis of chorismate synthase in Baphicacantus cusia and other 78 species of plants / 中国中药杂志

Chorismate synthase(CS, EC:4.2.3.5) catalyses 5-enolpyruvy-shikimate-3-phosphate to form chorismate, which is the essential enzyme for chorismate biosynthesis in organisms. The amino acid sequences of CS from 79 species of higher plants were reported in GenBank at present. 125 amino acid sequences of CS from Baphicacanthus cusia and other 78 species of plants were predicted and analyzed by using various bioinformatics software, including the composition of amino acid sequences, signal peptide, leader peptide, hydrophobic/hydrophilic, transmembrane structure, coiled-coil domain, protein secondary structure, tertiary structure and functional domains. The phylogenetic tree of CS protein family was constructed and divided into eight groups by phylogenetic analysis. The homology comparison indicated that B. cusia shared a high homology with several plants such as Sesamum indicum, Nicotiana tabacum, Solanum tuberosum and so on. The open reading frame(ORF) of all samples is about 1 300 bp, the molecular weight is about 50 kDa, the isoelectric point(pI) is 5.0-8.0 which illustrated that CS protein is slightly basic. The ORF of CS we cloned in B. cusia is 1 326 bp, the amino acid residues are 442, the molecular weight is 47 kDa and pI is 8.11. The CS in B.cusia showed obvious hydrophobicity area and hydrophilicity area, no signal peptide, and may exists transmembrane structure areas. The main secondary structures of CS protein are random coil and Alpha helix, also contain three main structural domains which are an active structural domain, a PLN02754 conserved domain and a FMN binding site. The acquired information in this study would provide certain scientific basis for further study on structure-activity relationship and structure modification of CS in plants in the future.

Structural analysis and molecular docking of potential ligands with chorismate synthase of Listeria monocytogenes: A novel antibacterial drug target.

Listeriosis, in particular that caused by Listeria monocytogenes, is a major foodborne pathogen, and its control is becoming difficult because of widespread emergence of drug resistance strains. Chorismate synthase (CS), an essential enzyme of shikimate pathway present only in bacteria, fungi, plant and some apicomplexan parasites, is a validated potential antimicrobial drug target. Antimicrobial development through the elucidation of essential structural features of the CS of L. monocytogenes (LmCS), identification and prioritization of potential lead compounds targeted against LmCS were done. Structure-based virtual screening and docking studies were performed using Autodock tools to retrieve potential candidates with high affinity binding against LmCS model from several ligand repositories. The potency of binding was also checked with other structurally similar CS from Streptococcus pneumoniae (SpCS) and Mycobacterium tuberculosis (MtCS). The sequence and structural studies revealed LmCS was similar to be other CS structures (1Q1L, 1QXO, 1R52, 1R53, 1SQ1, 1UM0, 1UMF, 1ZTB, 2011, 2012, 4ECD and 2G85) with each monomer presenting β-α-β sandwich topology with a central helical core. Molecular docking studies and ADME/Tox results revealed that ZINC03803450 and ZINC20149031 were most potent molecules binding into the active site of LmCS. Other two ligands ZINC13387711 and ZINC16052528 showed a strong binding affinity score against all three structures (LmCS, SpCS and MtCS) and bind to LmCS with the predicted inhibition constant (Ki) values of 22.94 nM and 35.84 nM, respectively. A reported benzofuran-3[2H]-one analog CHEMBL135212 with good ADME/Tox properties and experimental IC50 (nM) value of 7000 nM with SpCS could also be considered as a potential inhibitor of LmCS, as compared to previously reported 41 benzofuran-3[2H]-one analogs against SpCS. This information will assist in discovering those compounds that may act as potent CS inhibitors. Further experimental studies and evaluation of structure-activity relationship could help in the development of potential inhibitors against listeriosis, as well as antibacterial chemotherapy.

Activity of cyclic diguanylate (c-di-GMP) in bacteria and the study of its derivatives / 药学学报

Cyclic diguanylate (c-di-GMP) is a ubiquitous second messenger present in a wide variety of bacteria, which is responsible for cell differentiation, biofilm formation, pathogenic factor generation, and so on. The level of c-di-GMP in bacteria is regulated by two opposing active domains, diguanylate cyclase (DGC) and phosphodiesterase (PDE), which are present in the same bifunctional protein, and in charge of the synthesis and the degradation of c-di-GMP, respectively. The target of c-di-GMP in the bacterial cell consists of PilZ domain and GEMM riboswitch, the only riboswitch that involved in signal transduction. This article gives an overview of c-di-GMP, focusing on its metabolic pathway, regulatory mechanism, biological function of c-di-GMP, and the synthesis of c-di-GMP analogues and their biological activity.

Cloning and bioinformatics analysis of 2-c-methyl-D-erythritol 2,4-cyclodiphosphate synthase gene in Salvia miltiorrhiza / 中国中药杂志

<p><b>OBJECTIVE</b>To clone and analysis a 2-C-methyl-D-erythritol 2,4-cyclodiphosphate synthase (SmMCS) full-length eDNA from Salvia miltiorrhiza hairy roots.</p><p><b>METHOD</b>A full-length eDNA of SmMCS has been cloned by designing specific primers according to the transcriptome database and using the RACE strategy. ORF Finder was used to find the open reading frame of SmMCS cDNA and ClustalW has been performed to analysis the multiple amino acid sequence alignment. Phylogenetic tree has been constructed using MEGA 5. 1. Real-time quantitative PCR have been applied to detect the transcription level of SmMCS from hairy roots after elicitor Ag+ supplied.</p><p><b>RESULT</b>The SmMCS cDNA sequence was obtained. The full length of SmMCS (DNA was 988 bp encoding 234 amino acids. The deduced protein had isoelectric point (pI) of 8.53 and a calculated molecular weight about 24. 6 kDa. Results of real time PCR indicated that elicitor of Ag+ stimulated the increase of mRNA expression of SmMCS in hairy roots, and were increased dramatically at 12 h.</p><p><b>CONCLUSION</b>The full-length cDNA of SmMCS was cloned from S. miltiorrhiza hairy root,which can provide a gene target for further studies of tanshinones biosynthesis and terpenoid secondary metabolites.</p>

Research advances of diterpene synthase / 药学学报

Diterpenes, an important class of natural compounds, are widely distributed in nature. As the valuable diterpenoids continue to be found, diterpene synthase in the course of diterpene synthesis get as much attention as possible. The multiformity of end-product-diterpenoids were also due to the diversity of diterpene synthase. This paper focuses on the advances in recent biosynthesis pathway of diterpene and types, cloning, catalytic mechanism, synthetic biology application.

Diagnosis, treatment and gene mutation analysis of the first case with dihydropteridine reductase deficiency in the mainland of China / 中华儿科杂志

<p><b>OBJECTIVE</b>The 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency is the most common type of tetrahydrobiopterin (BH4) deficiency. The reported patients with BH4 deficiency are all PTPS deficient found in the mainland of China previously. The activity of dihydropteridine reductase in BH4 metabolism has been determined for 902 patients with hyperphenylalaninemia in the authors' laboratory since 2003. The purposes of this study were to characterize the first case with DHPR deficiency who was diagnosed in June, 2007, to investigate the clinical manifestation, the differential diagnostic criteria, the effect of treatment as well as gene mutation of DHPR deficiency.</p><p><b>METHODS</b>(1) A male patient presented with poor hand control, seizure, hypotonia and mental retardation since five-month after birth. His phenylalanine (Phe) level was 600 micromol/L and he was diagnosed as hyperphenylalaninemia at the age of one year and six-month. (2) This patient was subjected to combined Phe (100 mg/kg) and BH4 (20 mg/kg) loading test, to evaluate the degree of Phe level response to BH4. Urinary neopterin and biopterin analysis as well as the determination of DHPR activity in dried blood spot were also performed. (3) The blood DNA samples of the patient and his parents were collected to amplify the seven exons of QDPR gene using related primers, and the amplified products were directly sequenced for mutation analysis. (4) The patient was treated with BH4 or with a combined small amount of Phe-free special milk, neurotransmitter precursors and folic acid after the diagnosis and was followed up for clinical effects of treatment.</p><p><b>RESULTS</b>(1) The basic Phe level was 476 micromol/L, then it increased to 1355 micromol/L at 3 h after taking Phe and slowly decreased to 610 micromol/L at 24h after taking BH4. (2) The basic urinary neopterin and biopterin were 2.92 mmol/mol Cr (normally < 2.61 mmol/mol Cr) and 7.44 mmol/molCr (normally < 2.67 mmol/mol Cr) respectively, and biopterin percentage was 71.79% (normally 42.7% - 75.9%). The patient had higher biopterin level. (3) The DHPR activity of this patient was (0.27 - 0.51) nmol/(min.5 mm disc) which were 6.11% - 10.6% of normal control, so he was diagnosed as DHPR deficiency. (4) The analysis of QDPR gene mutation showed that the patient carries missense mutation c.515C > T (P172L) from his father and nonsense mutation c.661C > T (R221X) from his mother. The c.515C > T is not reported before, we also did not find this mutation in 50 normal children. (5) The patient started to be treated with large dosage of BH4 (10 - 20) mg/(kg.d) or BH4 combined with small amounts of Phe-free milk, neurotransmitter precursors L-dopa (3 - 5) mg/(kg.d) plus carbidopa, 5-hydroxytryptophan (3 - 5) mg/(kg.d), and folic acid 15 mg/d as well at the age of one year and six-month after the diagnosis. The seizure has disappeared, the symptoms such as hypotonia have been obviously improved and the Phe level was 60 micromol/L at the six months after the treatment in this patient.</p><p><b>CONCLUSION</b>(1) The patient with DHPR deficiency has common symptoms of BH4 deficiency (such as fair hair, hypotonia, mental retardation), and there is metabolic disturbance of folic acid in DHPR deficiency. (2) The higher Phe levels slowly decreased after BH4 loading test, the urinary biopterin level was very high and the DHPR activity was very low in the patient with DHPR deficiency. (3) The c.515C > T may be a new mutation of QDPR gene. (4) The DHPR deficient patient must be treated with higher dose of BH4 (8 - 20) mg/(kg.d), neurotransmitter precursors and folic acid as well.</p>

Mutation analysis and one novel mutation detection of 6-pyruvoyl tetrahydropterin synthase gene in children with tetrahydrobiopterin deficiency / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the distribution character of the mutations of 6-pyruvoyl tetrahydropterin synthase (PTPS) gene and to provide effective basis for gene diagnosis of tetrahydrobiopterin deficiency (BH4D) in children with hyperphenylalaninemia.</p><p><b>METHODS</b>Direct sequencing was performed for screening the PTPS gene mutations in 5 patients with clinically suspected BH4D and their parents. The nature of the novel mutations were deduced by the sequences alignment and the structural analysis of mutant protein. Artificial construct restriction site was used to detect the novel mutation in the control samples. The dates of urinary pterin analysis and BH4 loading test were retrospectively analyzed after gene analysis.</p><p><b>RESULTS</b>Four PTPS gene mutations (N52S, P87S, D96N, and L127F) were detected in our study. The genotypes of four PTPS deficiency patients were identified as N52S/L127F, P87S/D96N, N52S/D96N, and D96N/ -. As a novel mutation that has not been reported previously, the mutation L127F was not detected in 50 normal controls. This novel mutation L127F was inherited from the patient's mother, and this mutant site was highly conserved by sequences alignment and the protein structural analysis. Four of the five cases with hyperphenylalaninemia and suspicious BH4D, whose urinary biopterin percentage was lower than 2% , were diagnosed as PTPS deficiency during 5-20 months old. The remaining one case was excluded from BH4D.</p><p><b>CONCLUSIONS</b>The mutant characterization of PTPS gene was coincident with other early studies in Chinese. The novel mutation L127F was considered as a pathogenetic mutation and associated with severe clinical phenotype.</p>

Screening for tetrahydrobiopterin metabolic disorders and related gene analysis among the patients with motor disturbance and mental retardation / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the incidence of various enzyme deficiency in tetrahydrobiopterin (BH4) metabolism and the related gene mutation among the patients with motor disturbance and mental retardation.</p><p><b>METHODS</b>One hundred patients with unknown motor disturbance and mental retardation were referred to this study. All patients were performed by phenylalanine (Phe) and BH4 loading test, urinary pterin analysis and dihydropteridine reductase (DHPR) activity. Some patients received the dopa treatment for diagnosis of dopa-responsive dystonia (DRD). The analysis of GTP cyclohydrolase 1 gene (GCH1) mutation for DRD patients and the analysis of 6-pyruvoyl tetrahydropterin synthase (PTS) gene mutations for PTS deficient patients were done under the consent from their parents.</p><p><b>RESULTS</b>Seventy of 100 patients had normal basic blood Phe levels, six (6%) patients were diagnosed as DRD. Thirty patients had hyperphenylalaninemia (HPA), eight (8%) were diagnosed as PTS deficiency and 22(22%) were diagnosed as phenylalanine hydroxylase (PAH) deficiency. All patients had normal DHPR activity. The mutation IVS5+3insT of GCH1 was found in 2 patients with DRD. Seven kinds of PTS mutations were found in 8 patients with PTS deficiency, and 75% of the mutations were 259C-->T,286G-->A and 155A-->G.</p><p><b>CONCLUSION</b>Some patients with unknown motor disturbance and mental retardation may suffer from BH4 metabolism related diseases. Theses patients are necessary to be screened for such kind of diseases in order to confirm the diagnosis.</p>

6-pyruvoyltetrahydropterin synthase deficiency two-case report.

6-Pyruvoyltetrahydropterin Synthase (PTPS) deficiency is the most common cause of hyperphenylalaninemia due to tetrahydrobiopterin deficiency. The presenting symptoms of PTPS deficiency are mental retardation, convulsions, disturbance of tone and posture, drowsiness, irritability, abnormal movements, hypersalivation, and swallowing difficulties(1-3). The authors reported the first two cases of PTPS deficiency in Thailand. Both cases were male infants who showed phenylalanine levels of 25.23 mg/dl and 23.4 mg/dl respectively. The urinary pterins analysis showed low biopterin and high neopterin. The percentage of urinary biopterin was also found to be very low. The mutation analysis of the first case revealed a point mutation of exon 4, a homozygous C to T transition at nucleotide 200 in codon 67 (T67M), and the second case showed a compound heterozygous of exon 4, C to A transition at nucleotide 200, and exon 5, C to T transition at nucleotide 259 of the PTS gene confirming that they had PTPS deficiency. Treatment was started with neurotransmitters and a low phenylalanine diet. Family carriers were detected by means of urinary pterins determination and mutation analysis.

Detection of the prevalent mutations of 6-pyruvoyl-tetrahydropterin synthase gene by PCR-RFLP analysis in Chinese patients / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To establish a single and rapid method for detecting the prevalent mutations of 6-pyruvoyl-tetrahydropterin synthase (PTPS) gene in Chinese patients with 6-pyruvoyl-tetrahydropterin synthase deficiency (PTPSD).</p><p><b>METHODS</b>PCR-restriction fragment length polymorphism (PCR-RFLP) was used to detect three prevalent PTPS gene mutations in 4 cases of tetrahydrobiopterin deficiency (BH4D) and their parents, which was performed by the artificial construct restriction site (ACRS). PCR-RFLP included Hpa I digestion for the detection of mutation N52S (155A to G), Hae III for P87S (259C to T) and Eco R I for D96N(286G to A). The mutations of PTPS gene were confirmed by direct sequencing.</p><p><b>RESULTS</b>The genotypes of 4 PTPS deficient patients were identified: N52S/-, P87S/D96N, N52S/D96N and D96N/-. The result of direct sequencing was coincident with that of PCR-RFLP analysis.</p><p><b>CONCLUSION</b>(1) The PCR-RFLP analysis formed by ACRS would be a good way for detecting the three prevalent PTPS gene mutations in Chinese patients with PTPSD. (2)The PTPS gene analysis is very important for all patients with hyperphenylalaninemia, which would be useful for early clinical diagnosis and correct treatment of BH4D patients.</p>

Study on tetrahydrobiopterin deficiency in Northern Chinese population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To emphasize early differential diagnosis from patients with hyperphenylalaninemia (HPA) and to evaluate the treatment and long-term outcome of patients with tetrahydrobiopterin synthase (BH4) deficiency in Northern Chinese population.</p><p><b>METHODS</b>From 1992 to 2005, a total of 618 patients with HPA were diagnosed and/or cared for in our outpatient clinic. Urinary pterin analysis, detection of dihydropteridine reductase (DHPR) activity in blood, and then BH4 loading tests were carried out to differentiate BH4 deficiency in these patients from classical phenylketonuria. BH4 deficient patients were treated with BH4, levodopa and 5-hydroxytryptophane (5-HTP) immediately while the diagnosis was done to disease. Patientso blood phenylalanine levels, psychomotor and intelligence development were followed up.</p><p><b>RESULTS</b>A total of 38 cases were diagnosed as BH4 deficiency, all of them were revealed as 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency from the extremely decreased urine biopterin, normal DHPR activities and drop down of blood phenylalanine level to normal range within 4 to 8 hours after BH4 loading. The most common manifestations were progressively psychomotor and mental retardation to patients even after taking early dietary treatment. The patients were diagnosed and treated with drugs at the ages of 2.1 months to 13 years. With 4 patients died of pneumonia, 7 patients refused to treatment, only 27 patients were under treatment and followed up. The average full scale development or intelligence quotient (DQ/IQ) of patients who were treated within and after 6 months were 86+/- 10 or 66+/- 7 respectively. Development was not even in different aspects. A significant negative correlation was observed between the level of the DQ and the age of treatment commenced (r was -0.714, P< 0.01). Eleven patients experienced the extrapyramidal movement disorders, 3 of them combined with epilepsy. The extrapyramidal disorders were controlled by administration of levodopa.</p><p><b>CONCLUSION</b>The differential diagnosis for BH4 deficiency should be carried out in all patients with HPA. PTPS deficiency is the most common form of BH4 deficiency in Northern Chinese population. The long-term outcome of these patients benefits from diagnosis and treatment with BH4, levodopa and 5-HTP as early as possible.</p>

6-pyruvoyl tetrahydropterin synthase deficiency: a case report.

A 5 day old girl screened positive for hyperphenylalaninemia on routine newborn screening. Initial diagnostic work-up showed elevated blood phenylalanine of 1100 mmol/L and low tyrosine. Limited protein diet and phenylalanine-free formula were prescribed. Further investigation revealed a defect in biopterin metabolism. Urine had no detectable biopterin (BH4) and an elevated level of neopterin at 24.31 mmol/mole Cr. Enzymatic assay showed zero level of 6-pyruvoyl tetrahydropterin synthase. The activity in the mother was 3.5 or 19.9% of controls consistent with heterozygosity. The concentrations of 5-hydroxyindoleacetic acid and homovanillic acid in the cerebrospinal fluid were below the reference ranges. A treatment regimen of BH4 tablets, 5 hydroxytryptophan and DOPA was initiated. The diagnostic evaluation, management and follow-up of patients with this disorder will be outlined. This is the first reported case of a Filipino with a defect in biopterin metabolism.

An eighteen-year study on phenylketonuria / 中国医学科学院学报

A study on phenylketonuria (PKU) has been carried out in China-Japan Friendship Hospital since 1984. The results revealed that: (1) Totally 603 patients with PKU were diagnosed and treated in the hospital from October 1984 to September 2002. Among which 136 cases were identified by neonatal screening and treated within 3 months. One hundred and ninety-five cases were treated when the children were 3-12 months of age. Another 272 PKU children were diagnosed when they were more than 1 year old. All of these late-treated cases had some signs and symptoms of PKU. Mental retardation was found in 467 cases and various patterns of seizures in 119 cases. After treatment with low-phenylalanine diet, the follow-up for early-treated patients revealed that their physical and mental developments were normal. In late-treated patients, abnormal behaviour was significantly improved and their developmental quotient were elevated. Prenatal gene diagnosis of PKU risk foetus in 22 PKU families was successfully performed. (2) Urinary pterins obtained from 369 HPA patients were measured by HPLC. Twenty two patients with BH4 deficiency have been recognized. Six single base mutations were detected in 18 unrelated northern Chinese BH4 deficiency families, and the mutations at nucleotides 259C-->T and 286G-->A were common mutations. Eighteen BH4 deficient patients were treated with BH4, L-dopa and 5-hydroxytryptophan, and the results were satisfactory. (3) The abnormal rate of EEG was high in untreated patients with PKU, mainly showing epileptiform discharges and partly showing background activity abnormality. The most frequent finding was patchy areas of increased signal intensity in white matter on MRI in the brain of PKU patients, while delayed myelination and brain agenesis were often detected. After dietary treatment, follow-ups with EEG and MRI revealed that the abnormalities were decreased significantly. (4) The relationship between genotype and intellectual phenotype was examined in 29 late-treated patients with classical PKU. It was found that the genotype of 22 patients were compatible with intellectual phenotype and not well matched in 7 cases. The result indicate that the genotype was well matched with intellectual phenotype in classical PKU patients.

Screening for tetrahydrobiopterin deficiency among hyperphenylalaninemia patients in Southern China / 中华医学杂志(英文版)

<p><b>OBJECTIVES</b>To 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.</p><p><b>METHODS</b>Urinary 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.</p><p><b>RESULTS</b>Eleven 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.</p><p><b>CONCLUSIONS</b>Our 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.</p>