Phenylketonuria(PKU),a disease resulting in the disability to degrade phenylalanine(Phe)is an inborn error with a 1 in 10,000 morbidity rate on average around the world which leads to neurotoxicity.As an potential alt...Phenylketonuria(PKU),a disease resulting in the disability to degrade phenylalanine(Phe)is an inborn error with a 1 in 10,000 morbidity rate on average around the world which leads to neurotoxicity.As an potential alternative to a protein-restricted diet,oral intake of engineered probiotics degrading Phe inside the body is a promising treatment,currently at clinical stage II(Isabella,et al.,2018).However,limited transmembrane transport of Phe is a bottleneck to further improvement of the probiotic’s activity.Here,we achieved simultaneous degradation of Phe both intracellularly and extracellularly by expressing genes encoding the Phe-metabolizing enzyme phenylalanine ammonia lyase(PAL)as an intracellularly free and a cell surface-immobilized enzyme in Escherichia coli Nissle 1917(EcN)which overcomes the transportation problem.The metabolic engineering strategy was also combined with strengthening of Phe transportation,transportation of PAL-catalyzed trans-cinnamic acid and fixation of released ammonia.Administration of our final synthetic strain TYS8500 with PAL both displayed on the cell surface and expressed inside the cell to the Pah^(F263S)PKU mouse model reduced blood Phe concentration by 44.4%compared to the control Ec N,independent of dietary protein intake.TYS8500 shows great potential in future applications for PKU therapy.展开更多
Hyperphenylalaninemia is one of the commonest inborn errors of metabolism affecting approximately 1 in 15 000 live births. Among Chinese, BH4 deficiency leading to hyperphenylalaninemia is much commoner than in Caucas...Hyperphenylalaninemia is one of the commonest inborn errors of metabolism affecting approximately 1 in 15 000 live births. Among Chinese, BH4 deficiency leading to hyperphenylalaninemia is much commoner than in Caucasians. Exact diagnosis is important for the treatment and genetic counseling. In 2000, newborn screening for phenylketonuria is mandatory by law in China throughout the whole country. However, it is not yet included in the newborn screening program of the Hong Kong Special Administrative Region, China. Published data on hyperphenylalaninemia among Hong Kong Chinese are largely lacking. We report a 1-year-old Hong Kong Chinese girl with severe 6-pyruvoyl-tetrahydropterin synthase （PTPS） deficiency. The patient presented with infantile hypotonia and was misdiagnosed as cerebral palsy. She had very mild hyperphenylalaninemia （95 IJmol/L）, significantly high phenylalnine-to-tyrosine ratio （3.1）, and ele~,ated prolactin of 1109 m lU/L. Genetic analysis confirmed a homozygous known disease-causing mutation PTS NM_000317.1： c.259C〉T; NP_000308.1： p.P87S in the proband. In our local experience, while the estimated prevalence of hyperphenylalaninemia due to PTPS deficiency was reported to be 1 in 29 542 live births, not a single case of phenylalanine hydroxylase deficiency has been reported. Furthermore, there is a general lack of awareness of inherited metabolic diseases in the community as well as among the medical professionals. Very often, a low index of clinical suspicion will lead to delay in diagnosis, multiple unnecessary and costly investigations, prolonged morbidity and anxiety to the family affected. We strongly recommend that expanded newborn screening for hyperphenylalaninemia should be implemented for every baby born in the Hong Kong Special Administrative Region, China.展开更多
Point mutation is an important molecular mechanism leading to human geneticdiseases and remains one of the focal areas of research in gene diagnosis. This notereports a simple and rapid method for the detection of kno...Point mutation is an important molecular mechanism leading to human geneticdiseases and remains one of the focal areas of research in gene diagnosis. This notereports a simple and rapid method for the detection of known mutant phenylketonuria(PKU)alleles-Multiplex Allele-specific Polymerase Chain Reaction (MASPCR) whichcan identify several point mutations at the same time.展开更多
A silent mutation or sequence polymorphism, A to T substitution at codon 399 in exon11 of the PAH gene from a Chinese PKU patient, was found by sequence analysis. The fre-quencies of this new mutation in normal and ab...A silent mutation or sequence polymorphism, A to T substitution at codon 399 in exon11 of the PAH gene from a Chinese PKU patient, was found by sequence analysis. The fre-quencies of this new mutation in normal and abnormal (PKU) genes were 0.005 and 0.09,respectively, based on the analyses of 100 normal individuals and 39 PKU patients usingDNA amplification with polymerase chain reaction (PCR) and oligonucleotide hybridizationmethods. This silent mutation can be used as a "genetic marker" for PKU prenatal diagno-sis. Recently, a fetus at risk for PKU, who could not be completely predicted by RFLPslinkage analysis, was prenatally diagnosed with this genetic marker.展开更多
Background:Phenylketonuria(PKU)is caused by a defect in phenylalanine hydroxylase(PAH).More than 500 mutations have been reported for the gene encoding PAH.However,approximately l%-5%of these include large deletions a...Background:Phenylketonuria(PKU)is caused by a defect in phenylalanine hydroxylase(PAH).More than 500 mutations have been reported for the gene encoding PAH.However,approximately l%-5%of these include large deletions and large duplications that cannot be detected by conventional methods.Methods:In this report we tried to fully characterize a PAH-deficient patient.The patient was a 2-year-old Japanese boy who was diagnosed with classical PKU at the time of neonatal screening,which was confirmed by the tetrahydrobiopterin-loading test.PCR-related direct sequencing and multiplex ligation-dependent probe amplification(MLPA)were used to analyze of the PAH of the patient.Results:Using PCR-related direct sequencing method,we could detect only a heterozygous novel missense mutation:p.136G>C(p.G46R).A second mutation was detected by MLPA.The patient was heterozygous for a novel large deletion of exons 12 and 13:c.1200-?_1359+?del(EX12_13del).For genetic counseling,an accurate genetic diagnosis is often necessary.Conclusions:Through a combination of MLPA and conventional methods,the success rate of PAH mutation identification can be close to 100%.展开更多
Phenylketonuria(PKU)is an autosomal recessive metabolic disorder caused by deficiency of phenylalanine hydroxylase(PAH).The major molecular defects causing PKU are missense mutations of PAH gene.Large deletions of exo...Phenylketonuria(PKU)is an autosomal recessive metabolic disorder caused by deficiency of phenylalanine hydroxylase(PAH).The major molecular defects causing PKU are missense mutations of PAH gene.Large deletions of exon 5(EX5del955 and EX5del4232ins)were first reported by the Czech study and were later found also in the Polish,Slovak,Slovenian and Italian PKU-patients.These observations demonstrate the existence of a common subset of this mutation predominantly among Central European populations of Slavic descent.That is why we suggest that EX5del1955 and EX5del4232ins268 mutations might be frequent causes of PKU in Ukrainian patients.EX5del955 and EX5del4232ins268 mutations were analyzed in 106 unrelated PKU patients negative for PAH gene mutations on one or both alleles from our previous analysis.The simultaneous detection of EX5del4232ins268 and EX5del955 mutations was performed by PCR amplification of mutant alleles.EX5del955 mutation was not detected in the Ukrainian patients.This relative alleles frequency of EX5del4232ins268 mutation in the Ukrainian PKU population was determined as 1,66%.Our findings can be the one more evidence of Central European Slavic origin of EX5del4232ins268 mutation,suggested previously.This finding is important for the improvement of DNA diagnosis necessary for the management of PKU patients from Ukraine.展开更多
基金supported by the National Natural Science Foundation of China(21825804,31921006)the National Science&Technology Major Project“Key New Drug Creation and Manufacturing Program”,China(2018ZX09711002-019)the Shanghai Municipal Science and Technology Major Project and the National Key Research and Development Program of China(2018YFA0800603)。
文摘Phenylketonuria(PKU),a disease resulting in the disability to degrade phenylalanine(Phe)is an inborn error with a 1 in 10,000 morbidity rate on average around the world which leads to neurotoxicity.As an potential alternative to a protein-restricted diet,oral intake of engineered probiotics degrading Phe inside the body is a promising treatment,currently at clinical stage II(Isabella,et al.,2018).However,limited transmembrane transport of Phe is a bottleneck to further improvement of the probiotic’s activity.Here,we achieved simultaneous degradation of Phe both intracellularly and extracellularly by expressing genes encoding the Phe-metabolizing enzyme phenylalanine ammonia lyase(PAL)as an intracellularly free and a cell surface-immobilized enzyme in Escherichia coli Nissle 1917(EcN)which overcomes the transportation problem.The metabolic engineering strategy was also combined with strengthening of Phe transportation,transportation of PAL-catalyzed trans-cinnamic acid and fixation of released ammonia.Administration of our final synthetic strain TYS8500 with PAL both displayed on the cell surface and expressed inside the cell to the Pah^(F263S)PKU mouse model reduced blood Phe concentration by 44.4%compared to the control Ec N,independent of dietary protein intake.TYS8500 shows great potential in future applications for PKU therapy.
文摘Hyperphenylalaninemia is one of the commonest inborn errors of metabolism affecting approximately 1 in 15 000 live births. Among Chinese, BH4 deficiency leading to hyperphenylalaninemia is much commoner than in Caucasians. Exact diagnosis is important for the treatment and genetic counseling. In 2000, newborn screening for phenylketonuria is mandatory by law in China throughout the whole country. However, it is not yet included in the newborn screening program of the Hong Kong Special Administrative Region, China. Published data on hyperphenylalaninemia among Hong Kong Chinese are largely lacking. We report a 1-year-old Hong Kong Chinese girl with severe 6-pyruvoyl-tetrahydropterin synthase （PTPS） deficiency. The patient presented with infantile hypotonia and was misdiagnosed as cerebral palsy. She had very mild hyperphenylalaninemia （95 IJmol/L）, significantly high phenylalnine-to-tyrosine ratio （3.1）, and ele~,ated prolactin of 1109 m lU/L. Genetic analysis confirmed a homozygous known disease-causing mutation PTS NM_000317.1： c.259C〉T; NP_000308.1： p.P87S in the proband. In our local experience, while the estimated prevalence of hyperphenylalaninemia due to PTPS deficiency was reported to be 1 in 29 542 live births, not a single case of phenylalanine hydroxylase deficiency has been reported. Furthermore, there is a general lack of awareness of inherited metabolic diseases in the community as well as among the medical professionals. Very often, a low index of clinical suspicion will lead to delay in diagnosis, multiple unnecessary and costly investigations, prolonged morbidity and anxiety to the family affected. We strongly recommend that expanded newborn screening for hyperphenylalaninemia should be implemented for every baby born in the Hong Kong Special Administrative Region, China.
基金Project sponsored by China Medical Board (CMB)National 863 High Technology and Natural Science Foundation.
文摘Point mutation is an important molecular mechanism leading to human geneticdiseases and remains one of the focal areas of research in gene diagnosis. This notereports a simple and rapid method for the detection of known mutant phenylketonuria(PKU)alleles-Multiplex Allele-specific Polymerase Chain Reaction (MASPCR) whichcan identify several point mutations at the same time.
文摘A silent mutation or sequence polymorphism, A to T substitution at codon 399 in exon11 of the PAH gene from a Chinese PKU patient, was found by sequence analysis. The fre-quencies of this new mutation in normal and abnormal (PKU) genes were 0.005 and 0.09,respectively, based on the analyses of 100 normal individuals and 39 PKU patients usingDNA amplification with polymerase chain reaction (PCR) and oligonucleotide hybridizationmethods. This silent mutation can be used as a "genetic marker" for PKU prenatal diagno-sis. Recently, a fetus at risk for PKU, who could not be completely predicted by RFLPslinkage analysis, was prenatally diagnosed with this genetic marker.
文摘Background:Phenylketonuria(PKU)is caused by a defect in phenylalanine hydroxylase(PAH).More than 500 mutations have been reported for the gene encoding PAH.However,approximately l%-5%of these include large deletions and large duplications that cannot be detected by conventional methods.Methods:In this report we tried to fully characterize a PAH-deficient patient.The patient was a 2-year-old Japanese boy who was diagnosed with classical PKU at the time of neonatal screening,which was confirmed by the tetrahydrobiopterin-loading test.PCR-related direct sequencing and multiplex ligation-dependent probe amplification(MLPA)were used to analyze of the PAH of the patient.Results:Using PCR-related direct sequencing method,we could detect only a heterozygous novel missense mutation:p.136G>C(p.G46R).A second mutation was detected by MLPA.The patient was heterozygous for a novel large deletion of exons 12 and 13:c.1200-?_1359+?del(EX12_13del).For genetic counseling,an accurate genetic diagnosis is often necessary.Conclusions:Through a combination of MLPA and conventional methods,the success rate of PAH mutation identification can be close to 100%.
基金We cordially thank all PKU families who participated in this study.This study was supported by a grant from the National Academy of Science of Ukraine(no.0115U003747).
文摘Phenylketonuria(PKU)is an autosomal recessive metabolic disorder caused by deficiency of phenylalanine hydroxylase(PAH).The major molecular defects causing PKU are missense mutations of PAH gene.Large deletions of exon 5(EX5del955 and EX5del4232ins)were first reported by the Czech study and were later found also in the Polish,Slovak,Slovenian and Italian PKU-patients.These observations demonstrate the existence of a common subset of this mutation predominantly among Central European populations of Slavic descent.That is why we suggest that EX5del1955 and EX5del4232ins268 mutations might be frequent causes of PKU in Ukrainian patients.EX5del955 and EX5del4232ins268 mutations were analyzed in 106 unrelated PKU patients negative for PAH gene mutations on one or both alleles from our previous analysis.The simultaneous detection of EX5del4232ins268 and EX5del955 mutations was performed by PCR amplification of mutant alleles.EX5del955 mutation was not detected in the Ukrainian patients.This relative alleles frequency of EX5del4232ins268 mutation in the Ukrainian PKU population was determined as 1,66%.Our findings can be the one more evidence of Central European Slavic origin of EX5del4232ins268 mutation,suggested previously.This finding is important for the improvement of DNA diagnosis necessary for the management of PKU patients from Ukraine.
