OBJECTIVETo investigate the type and frequency of mutations in exon 7 of phenylalanine hydroxylase (PAH) gene among children with phenylketonuria (PKU) in Ningxia, China and to provide a basis for the genetic diagnosis and prenatal diagnosis of PKU in this region.

METHODSDirect sequencing of PCR product was performed to analyze the sequences of exon 7 and its flanking introns of 146 PAH alleles in 73 children with typical PKU (39 cases of Hui nationality and 34 cases of Han nationality) in Ningxia.

RESULTSSix mutations were detected, including R243Q (14.4%), R241C (6.8%), IVS7+2T→A (2.7%), L255S (0.7%), G247V (0.7%), and G247R (0.7%). The overall frequency of mutations (missense mutation and splice site mutation) in exon 7 was 26.0% (38/146). The detection rate of R241C mutation was significantly higher in children of Hui nationality than in children of Han nationality(10% vs 3%; P<0.05).

CONCLUSIONSIn Ningxia, R243Q mutation in exon 7 of PAH gene is most common in children with PKU, followed by R241C. The frequency of R241C mutation in exon 7 of PAH gene varies between children with PKU of Hui and Han nationality.

China ; ethnology ; Exons ; Humans ; Mutation ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; genetics

PURPOSE: Phenylketonuria(PKU) is an inborn error of metabolism and a genetic disorder resulting from a deficiency of phenylalanine hydroxylase(PAH) and decreased activity of tetrahydrobiopterin(BH4).In this study the correlation between the DNA mutation and clinical manifestations was investigated and PAH DNA mutations were compared bewteen Asian and Caucasian populations. METHODS: DNA was isolated from peripheral leukocytes. The PAH gene was amplified by Polymerase Chain Reaction(PCR) and the sequence was analyzed with Multiplex Ligation-dependent Probe Amplification(MLPA). RESULTS: We characterized the PAH gene of 102 independent Korean patients with PKU. PAH nucleotide sequence analysis revealed 44 different mutations, including 10 novel mutations comprising 9 missense mutations(N207D, K95del, A447P, G344D, P69S, S391I, A202T, G103S, and I306L) and 1 novel splice-site variant mutation(IVS10-3C>G). R243Q was the most prevalent mutation in this study. A259T has not previously been reported in Asian populations, but we found that this mutation had a frequency of 10.1% in our study. Furthermore, the genotypes of BH4 responsive patients were analyzed and were divided into two groups: BH4 medication-only group and BH4 medication with diet therapy group. In the BH4 medication-only group and BH4 medication with diet therapy group, R241C was the most common mutation. CONCLUSION: Novel mutations in the PAH gene of PKU patients are still being discovered. Additional information as to the frequency of mutations in the tetrahydrobiopterine responsive gene is also accumulating. We anticipate that knowledge of these PKU gene mutations will assist the diagnosis, genetic counseling, and therapeutic treatment of PKU patients in future.
Asian Continental Ancestry Group ; Base Sequence ; DNA ; Genetic Counseling ; Genotype ; Humans ; Leukocytes ; Phenylalanine ; Phenylalanine Hydroxylase ; Phenylketonurias

The biogenic monoamine 5-hydroxytryptamine (5-HT) is an ancient intracellular signaling molecule widely distributed in all animals with nervous systems, and has been implicated in principal behaviors. Tryptophan hydroxylase (TRH) induces a highly specific catalytic reaction that converts L-tryptophan (tryptophan) to 5-hydroxy-L-tryptophan (5-HTP) that is subsequently used as a substrate by aromatic L-amino acid decarboxylase (DDC) to form 5-HT. Five-HT is an ancient intracellular signaling molecule that is widely distributed in the animal kingdom and has been implicated in regulating the behaviors of animals with nervous systems. However, the role of TRH in Lepidoptera is not well understood. In this study, we cloned 1 667 bp cDNAs of Bombyx mori TRH (BmTRH), which contains a 1 632 bp open reading frame (ORF). Homology analysis revealed that BmTRH shared high amino acid identity with Homo sapiens TPH and Drosophila TRH (DmTRH). The high homology (70%) of BmTRH with DmTRH suggested that BmTRH could have a function similar to DmTRH. Gene expression analysis revealed that BmTRH was mainly expressed in head and central nervous (CNS). Moreover, immunohistochemistry and Western blotting analyses showed that BmTRH was detected only in larval nervous tissues. Taken together, our results indicate that BmTRH could likely function in the regulation of neural activities in B. mori. The transcripts of B. mori decarboxylase (BmDDC) and B. mori phenylalanine hydroxylase (BmPAH) whose proteins had TRH activity, were also expressed in the CNS tissues, indicating that unlike in Drosophila, two distinct mechanisms likely regulate 5-HT synthesis in silkworm.
Amino Acid Sequence ; Animals ; Bombyx ; Cloning, Molecular ; DNA, Complementary ; Insect Proteins ; Phenylalanine Hydroxylase ; Tryptophan Hydroxylase

INTRODUCTION: Phenylketonuria (PKU), an autosomal recessive metabolic disorder caused by phenylalanine hydroxylase (PAH) deficiency, leads to hyperphenylalaninemia and neurological damage if untreated. This is the first study in the Philippines to identify the disease-causing mutations in the PAH gene of clinically diagnosed Filipino PKU patients.

METHODS: The study included four unrelated PKU patients detected by the Philippine Newborn Screening Program from 1996 to 2008. Plasma amino acid analyses for all patients showed increased phenylalanine and low to normal tyrosine levels consistent with the diagnosis of PKU. Mutations in the PAH gene were identified by genomic DNA extraction from dried blood spots of the patients, PAH exon amplification by polymerase chain reaction and subsequent bi-directional DNA sequence analysis.

RESULTS: All patients presented with significantly elevated phenylalanine levels on bacterial inhibition assay and thin layer chromatography. Urinary pterins confirmed the diagnosis of Tetrahydrobiopterin deficiency in two patients while the other 2 patients had the Classical PKU phenotype. Four previously identified mutations in the PAH gene (p.I65T, p.R413P, p.EX6-96A>G, p.R243Q) were identified in those with Classical PKU.

CONCLUSION: The present results confirm the heterogeneity of mutations at the PAH locus in Filipinos. Neonatal screening and the use of molecular diagnosis significantly aid in the medical management and genetic counseling of patients and their families.

Phenylalanine Hydroxylase ; Phenylalanine ; Neonatal Screening ; Genetic Counseling ; Tyrosine ; Pterins ; Chromatography, Thin Layer ; Philippines ; Phenylketonurias ; Exons ; Sequence Analysis, Dna ; Phenotype ; Dna

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

Phenylalanine hydroxylase (PAH) is a member of aromatic amino acid hydroxylase (AAAHs) family, and catalyze phenylalanine (Phe) into tyrosine (Tyr). Using immunological and RT-PCR methods to prove the existence of phenylalanine hydroxylase (PAH) gene in the brain of Neanthes japonica in protein and nucleic acid level. Using Western blotting to detect the pah immunogenicity of Neanthes japonica. Making paraffin sections and using immunohistochemical technique to identify the presence and distribution of the phenylalanine hydroxylase gene in the brain of Neanthes japonica. Clone pah gene from the brain of Neanthes japonica by RT-PCR, constructing plasmid and transferring into E. coli to amplification, picking a single homogeneous colony, double digesting then making sequence and comparing homology. Western blotting results showed that the expression of the protein is present in Neanthes japonica brain, immunohistochemistry technique results showed that phenylalanine hydroxylase mainly expressed in abdominal of forebrain, dorsal and sides of midbrain. RT-PCR technique results showed that the phenylalanine hydroxylase exist in the brain of Neanthes japonica and has a high homology with others animals. PAH is present in the lower organisms Neanthes japonica, in protein and nucleic acid level. Which provide the foundation for further study the evolution of aromatic amino acid hydroxylase genes in invertebrate.
Animals ; Blotting, Western ; Brain ; enzymology ; Escherichia coli ; metabolism ; Phenylalanine Hydroxylase ; genetics ; metabolism ; Polychaeta ; enzymology ; genetics

OBJECTIVETo delineate the mutation spectrum of phenylalanine hydroxylase (PAH) gene among patients affected with phenylalanine hydroxylase deficiency (PAHD) in Henan Province of China, and to explore the correlation between the genotype and the phenotype.

METHODSA total of 155 affected children were recruited. Potential mutation of the PAH gene were analyzed by direct sequencing. The genotype-phenotype correlation was analyzed by matching the expected and observed phenotypes.

RESULTSOver 72 mutations and 108 genotypes have been identified. There were 7 homozygous mutations, including 1 case with EX6-96A>G/EX6-96A>G, 1 with R241C/R241C, 1 with R413P/R413P, and 4 with R243Q/R243Q. Among these, 6 patients have presented classic PKU phenotypes, except for a R241C/R241C genotype which has led to mild PKU. In 104 patients carrying compound PAH mutations, 52 were classic, 34 were mild and 39 had mild HPA. Patients who were heterozygous for EX6-96A>G/R241C, R243Q/A434D, EX6-96A>G/R413P and EX6-96A>G/ R241C were found with both the classic PKU and mild PKU phenotypes. Common mutations associated with mild HPA have included R53H, R243Q, V399V and H107R. The common mutations associated with mild PKU included R243Q, R241C, EX6-96A>G, and IVS4-1G>A. The prevalent mutations in classic PKU were R243Q, EX6-96A>G and V399V. The consistency between prediction of the biochemical genotype and observed phenotype was 77.78%, especially in classic PKU, the consistency was up to 82.14%. Significant correlations were disclosed between pretreatment levels of phenylalanine and AV sum (r=-0.6729, P < 0.01).

CONCLUSIONThe mutation spectrum of PAH gene in Henan seems to differ from that of other regions. Independent assortment of mutant alleles may result in a complex genotype-phenotype correlation, but the genotypes of PAHD patients have correlated with the phenotype.

Female ; Genotype ; Humans ; Male ; Mutation ; Phenotype ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; genetics

This study reports a boy with psychomotor retardation and epilepsy due to maternal phenylketonuria (PKU). The boy was admitted at the age of 20 months because of psychomotor retardation and epilepsy. He had seizures from the age of 1 year. His development quotient was 43. He presented with microcephaly, normal skin and hair color. Brain MRI scan showed mild cerebral white matter demyelination, broadening bilateral lateral ventricle and foramen magnum stricture. Chromosome karyotype, urine organic acids, blood amino acids and acylcarnitines were normal. His mother had mental retardation from her childhood. She presented with learning difficulties and yellow hair. Her premarriage health examinations were normal. She married a healthy man at age of 26 years. When she visited us at 28 years old, PKU was found by markedly elevated blood phenylalanine (916.54 μmol/L vs normal range 20-120 μmol/L). On her phenylalanine hydroxylase (PAH) gene, a homozygous mutations c.611A>G (p.Y204C) was identified, which confirmed the diagnosis of PAH-deficient PKU. Her child carries a heterozygous mutation c.611A>G with normal blood phenylalanine. Her husband had no any mutation on PAH. It is concluded that family investigation is very important for the etiological diagnosis of the children with mental retardation and epilepsy. Carefully clinical and metabolic survey should be performed for the parents with mental problems to identify parental diseases-associated child brain damage, such as maternal PKU.
Adult ; Epilepsy ; etiology ; Female ; Humans ; Infant ; Intellectual Disability ; etiology ; Male ; Phenylalanine Hydroxylase ; genetics ; Phenylketonuria, Maternal ; Pregnancy

OBJECTIVETo study the mutation characteristics of the phenylalanine hydroxylase (PAH) gene in children with phenylketonuria (PKU) from the Qinghai area of China, in order to provide basic information for genetic counseling and prenatal diagnosis.

METHODSMutations of the PAH gene were detected in the promoter and exons 1-13 and their flanking intronic sequences of PAH gene by PCR and DNA sequencing in 49 children with PKU and their parents from the Qinghai area of China.

RESULTSA total of 30 different mutations were detected in 80 out of 98 mutant alleles (82%), including 19 missense (63%), 5 nonsense (17%), 3 splice-site (10%) and 3 deletions (10%). Most mutations were detected in exons 3, 6, 7, 11 and intron 4 of PAH gene. The most frequent mutations were p.R243Q (19%), IVS4-1G>A (9%), p.Y356X (7%) and p.EX6-96A>G(5%). Two novel mutations p.N93fsX5 (c.279-282delCATC) and p.G171E (c.512G>A) were found. p.H64fsX9(c.190delC) was documented for the second time in Chinese PAH gene. The mutation spectrum of the gene PAH in the Qinghai population was similar to that in other populations in North China while significantly different from that in the populations from some provinces in southern China, Japan and Europe.

CONCLUSIONSThe mutations of PAH gene in the Qinghai area of China demonstrate a unique diversity, complexity and specificity.

Child ; Child, Preschool ; China ; Female ; Humans ; Infant ; Male ; Mutation ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; genetics

OBJECTIVE: To explore the characteristics of PAH gene variants among 113 phenylketonuria patients from Henan Province. METHODS: The 13 exons of the PAH gene were subjected to PCR amplification and direct sequencing. Large fragment deletion and duplication of the PAH gene were detected with a multiple ligation-dependent probe amplification (MLPA) assay. RESULTS: In total 195 point variants and 3 large fragment deletions were detected among the 226 alleles, with the detection rates being 86.28% and 1.33%, respectively. Variants of p.Arg243Gln (18.14%), p.Arg111X (6.19%), p.Arg53His (5.31%), EX6-96A>G (5.31%), p.Tyr356X (4.87%) and p.Val399Val (4.42%) were relatively common. Most of the variants were located in exons 7, 11, 3 and 6. Missense variations were most common. Four novel variations were detected, which included c.1016C>A (p.Ser339Tyr), c.1000T>C (p.Cys334Arg), c.1110G>T (p.Glu370Asp), and IVS6+1G>T. CONCLUSION The PAH gene variations in Henan Province have featured extensive allelic heterogeneity and variety.
China ; Exons ; Humans ; Mutation, Missense ; Phenylalanine Hydroxylase ; genetics ; Phenylketonurias ; genetics ; Point Mutation ; Sequence Deletion