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Çıkı K, Yıldız Y, Kahraman AB, Özgül RK, Coşkun T, Dursun A, Tokatlı A, Sivri S. Predictors of eventual requirement of phenylalanine-restricted diet in young infants with phenylalanine hydroxylase deficiency initially managed with sapropterin monotherapy. Mol Genet Metab 2023; 140:107706. [PMID: 37837865 DOI: 10.1016/j.ymgme.2023.107706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 10/02/2023] [Accepted: 10/02/2023] [Indexed: 10/16/2023]
Abstract
BACKGROUND Phenylalanine (Phe)-restricted diet is associated with lower quality of life for patients with phenylketonuria (PKU), and a concern for caregivers of recently-diagnosed infants. Sapropterin is an oral drug used as an alternative or adjunct to dietary treatment. We have observed that some of the young infants initially managed successfully with sapropterin monotherapy have required dietary treatment in long-term follow-up. We aimed to determine the baseline factors associated with future initiation of dietary treatment in these patients. METHODS Data were obtained retrospectively from the medical records of 80 PKU patients started on sapropterin monotherapy before 3 months of age between 2011 and 2021. RESULTS The patients were followed for a median of 3.9 years (Q1-Q3: 2.5-5.75 years). Sapropterin was tapered down and discontinued in 5 patients (6.3%) as their Phe levels remained below 360 μmol/L without treatment. Sapropterin monotherapy was sufficient in 62 patients (77.5%), while 13 (16.2%) required dietary treatment. Phe and tyrosine (Tyr) levels, and Phe:Tyr ratios differed significantly among the patients maintained on sapropterin monotherapy and those started on dietary treatment, but the Phe:Tyr ratio at diagnosis was the most important independent baseline variable (OR: 1.61, 95% CI: 1.15-2.27, p = 0.006), with Phe:Tyr ratio at diagnosis >5.25 associated with dietary treatment (sensitivity: 90.0%, specificity: 81.8%). Genotypic phenotype value (GPV), unavailable at baseline, was also associated with dietary treatment (median GPV 9.2 vs. 3.8, p = 0.006), but some genotypes were not specific to the final treatment modality. DISCUSSION We propose that the Phe:Tyr ratio at diagnosis is an important indicator to predict dietary requirement in young infants initially managed with sapropterin monotherapy.
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Affiliation(s)
- Kısmet Çıkı
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Yılmaz Yıldız
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Ayça Burcu Kahraman
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - R Köksal Özgül
- Hacettepe University Institute of Child Health, Ankara, Turkey.
| | - Turgay Coşkun
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Ali Dursun
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Ayşegül Tokatlı
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
| | - Serap Sivri
- Division of Pediatric Metabolism, Department of Pediatrics, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
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Tendi EA, Morello G, Guarnaccia M, La Cognata V, Petralia S, Messina MA, Meli C, Fiumara A, Ruggieri M, Cavallaro S. Detection of Single-Nucleotide and Copy Number Defects Underlying Hyperphenylalaninemia by Next-Generation Sequencing. Biomedicines 2023; 11:1899. [PMID: 37509538 PMCID: PMC10377317 DOI: 10.3390/biomedicines11071899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 06/27/2023] [Accepted: 06/29/2023] [Indexed: 07/30/2023] Open
Abstract
Hyperphenylalaninemia (HPA) is the most common inherited amino acid metabolism disorder characterized by serious clinical manifestations, including irreversible brain damage, intellectual deficiency and epilepsy. Due to its extensive genic and allelic heterogeneity, next-generation sequencing (NGS) technology may help to identify the molecular basis of this genetic disease. Herein, we describe the development and validation of a targeted NGS (tNGS) approach for the simultaneous detection of single-nucleotide changes and copy number variations (CNVs) in genes associated with HPA (PAH, GCH1, PTS, QDPR, PCBD1, DNAJC12) or useful for its differential diagnosis (SPR). Our tNGS approach offers the possibility to detail, with a high accuracy and in a single workflow, the combined effect of a broader spectrum of genomic variants in a comprehensive view, providing a significant step forward in the development of optimized patient care and management.
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Affiliation(s)
- Elisabetta Anna Tendi
- Biomedical Sciences Department, Institute for Biomedical Research and Innovation, National Research Council, Via Paolo Gaifami 18, 95026 Catania, Italy
| | - Giovanna Morello
- Biomedical Sciences Department, Institute for Biomedical Research and Innovation, National Research Council, Via Paolo Gaifami 18, 95026 Catania, Italy
| | - Maria Guarnaccia
- Biomedical Sciences Department, Institute for Biomedical Research and Innovation, National Research Council, Via Paolo Gaifami 18, 95026 Catania, Italy
| | - Valentina La Cognata
- Biomedical Sciences Department, Institute for Biomedical Research and Innovation, National Research Council, Via Paolo Gaifami 18, 95026 Catania, Italy
| | - Salvatore Petralia
- Department of Drug and Health Sciences, University of Catania, 95125 Catania, Italy
| | - Maria Anna Messina
- Regional Reference Center for the Treatment and Control of Congenital Metabolic Diseases of Childhood, Department of Clinical and Experimental Medicine, University Hospital Policlinico "Rodolico-San Marco", 95123 Catania, Italy
| | - Concetta Meli
- Regional Reference Center for the Treatment and Control of Congenital Metabolic Diseases of Childhood, Department of Clinical and Experimental Medicine, University Hospital Policlinico "Rodolico-San Marco", 95123 Catania, Italy
| | - Agata Fiumara
- Regional Reference Center for the Treatment and Control of Congenital Metabolic Diseases of Childhood, Department of Clinical and Experimental Medicine, University Hospital Policlinico "Rodolico-San Marco", 95123 Catania, Italy
| | - Martino Ruggieri
- Unit of Rare Diseases of the Nervous System in Childhood, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University Hospital Policlinico "Rodolico-San Marco", 95123 Catania, Italy
| | - Sebastiano Cavallaro
- Biomedical Sciences Department, Institute for Biomedical Research and Innovation, National Research Council, Via Paolo Gaifami 18, 95026 Catania, Italy
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Wang L, He B, Jin Q, Bai R, Yu W, Qiang R, Wang X. Allelic dropout in PAH affecting the results of genetic diagnosis in phenylketonuria. J Pediatr Endocrinol Metab 2022; 35:387-391. [PMID: 35026061 DOI: 10.1515/jpem-2021-0336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 12/29/2021] [Indexed: 11/15/2022]
Abstract
OBJECTIVES Phenylketonuria (PKU) is an inherited autosomal recessive disorder of phenylalanine metabolism. It is mainly caused by a deficiency in phenylalanine hydroxylase (PAH) and frequently diagnosed with Sanger sequencing. To some extent, allelic dropout can explain the inconsistency in genotype and phenotype. METHODS Three families were evaluated through DNA sequence analysis, multiplex ligation-dependent probe amplification (MLPA) and prenatal diagnosis technologies. The possibility of inconsistency in phenotype and genotype with c.331C>T variant was analysed. RESULTS Through pedigree analysis, three mothers carried a homozygous c.331C>T variant, which was a false-positive result. New primers were used, and this error was caused by allelic dropout. In this case, c.158G>A was likely a benign variant. CONCLUSIONS Sequence variants in primer-binding regions could cause allelic dropout, creating unpredictable errors in genotyping. Our results emphasised the need for careful measures to treat genotype-phenotype inconsistencies.
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Affiliation(s)
- Lin Wang
- Northwest Women's and Children's Hospital, Xi'an, Shaanxi, P. R. China
| | - Bin He
- Northwest Women's and Children's Hospital, Xi'an, Shaanxi, P. R. China
| | - Qiujie Jin
- Northwest Women's and Children's Hospital, Xi'an, Shaanxi, P. R. China
| | - Ruimiao Bai
- Northwest Women's and Children's Hospital, Xi'an, Shaanxi, P. R. China
| | - Wenwen Yu
- Northwest Women's and Children's Hospital, Xi'an, Shaanxi, P. R. China
| | - Rong Qiang
- Northwest Women's and Children's Hospital, Xi'an, Shaanxi, P. R. China
| | - Xiaobin Wang
- Northwest Women's and Children's Hospital, Xi'an, Shaanxi, P. R. China
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Muntau AC, Adams DJ, Bélanger-Quintana A, Bushueva TV, Cerone R, Chien YH, Chiesa A, Coşkun T, de Las Heras J, Feillet F, Katz R, Lagler F, Piazzon F, Rohr F, van Spronsen FJ, Vargas P, Wilcox G, Bhattacharya K. International best practice for the evaluation of responsiveness to sapropterin dihydrochloride in patients with phenylketonuria. Mol Genet Metab 2019; 127:1-11. [PMID: 31103398 DOI: 10.1016/j.ymgme.2019.04.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2019] [Revised: 03/14/2019] [Accepted: 04/13/2019] [Indexed: 12/26/2022]
Abstract
Phenylketonuria (PKU) is an inherited metabolic disease caused by phenylalanine hydroxylase (PAH) deficiency. As the resulting high blood phenylalanine (Phe) concentration can have detrimental effects on brain development and function, international guidelines recommend lifelong control of blood Phe concentration with dietary and/or medical therapy. Sapropterin dihydrochloride is a synthetic preparation of tetrahydrobiopterin (6R-BH4), the naturally occurring cofactor of PAH. It acts as a pharmacological chaperone, reducing blood Phe concentration and increasing dietary Phe tolerance in BH4-responsive patients with PAH deficiency. Protocols to establish responsiveness to sapropterin dihydrochloride vary widely. Two meetings were held with an international panel of clinical experts in PKU management to develop recommendations for sapropterin dihydrochloride response testing. At the first meeting, regional differences and similarities in testing practices were discussed based on guidelines, a literature review, outcomes of a global physician survey, and case reports. Statements developed based on the discussions were sent to all participants for consensus (>70% of participants) evaluation using a 7-level rating system, and further discussed during the second meeting. The experts recommend sapropterin dihydrochloride response testing in patients with untreated blood Phe concentrations of 360-2000 μmol/L, except in those with two null mutations. For neonates, a 24-h sapropterin dihydrochloride loading test is recommended; responsiveness is defined as a decrease in blood Phe ≥30%. For older infants, children, adolescents, and adults, a test duration of ≥48 h or a 4-week trial is recommended. The main endpoint for a 48-h to 7-day trial is a decrease in blood Phe, while improved Phe tolerance is the endpoint to be assessed during a longer trial. Longer trials may not be feasible in some locations due to lack of reimbursement for hospitalization, while a 4-week trial may not be possible due to limited access to sapropterin dihydrochloride or public health regulation. A 48-h response test should be considered in pregnant patients who cannot achieve blood Phe ≤360 μmol/L with a Phe-restricted diet. Durability of response and clinical benefits of sapropterin dihydrochloride should be assessed over the long term. Harmonization of protocols is expected to improve identification of responders and comparability of test results worldwide.
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Affiliation(s)
- Ania C Muntau
- University Children's Hospital, University Medical Center Hamburg Eppendorf, Hamburg, Germany.
| | - Darius J Adams
- Atlantic Health System, Morristown Medical Center, Morristown, NJ, USA.
| | | | - Tatiana V Bushueva
- National Medical Research Center of Children's Health of the Ministry of Health of the Russian Federation, Moscow, Russia.
| | - Roberto Cerone
- G. Gaslini Institute, University of Genova, Genova, Italy.
| | | | - Ana Chiesa
- Centro de Investigaciones Endocrinologicas "Dr Cesar Bergadá" CEDIE, CONICET, Hospital de Niños Ricardo Gutierrez, Fundacion de Endocrinologia Infantil, Buenos Aires, Argentina.
| | - Turgay Coşkun
- Hacettepe University Faculty of Medicine, Ankara, Turkey.
| | - Javier de Las Heras
- Hospital Universitario de Cruces, Biocruces Health Research Institute and University of the Basque Country UPV/EHU, Vizcaya, Spain.
| | - François Feillet
- Children's University Hospital, CHU Brabois, Vandoeuvre les Nancy, France.
| | - Rachel Katz
- Ann and Robert Lurie Children's Hospital of Chicago, Chicago, IL, USA.
| | | | - Flavia Piazzon
- Associação de Pais e Amigos dos Excepcionais de São Paulo (APAE DE SÃO PAULO), São Paulo, SP, Brazil.
| | - Fran Rohr
- Boston Children's Hospital, Boston, MA, USA.
| | - Francjan J van Spronsen
- Beatrix Children's Hospital, University Medical Center of Groningen, University of Groningen, Groningen, the Netherlands.
| | - Paula Vargas
- Hospital Materno Infantil Presidente Vargas, Porto Alegre, RS, Brazil.
| | - Gisela Wilcox
- University of Manchester & Salford Royal NHS Foundation Trust, Salford, UK.
| | - Kaustuv Bhattacharya
- Genetic Metabolic Disorders Service, University of Sydney, Children's Hospital Westmead Clinical School, Sydney, NSW, Australia.
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Vieira Neto E, Laranjeira F, Quelhas D, Ribeiro I, Seabra A, Mineiro N, Carvalho LM, Lacerda L, Ribeiro MG. Genotype-phenotype correlations and BH 4 estimated responsiveness in patients with phenylketonuria from Rio de Janeiro, Southeast Brazil. Mol Genet Genomic Med 2019; 7:e610. [PMID: 30829006 PMCID: PMC6503030 DOI: 10.1002/mgg3.610] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 01/15/2019] [Accepted: 01/24/2019] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Genetic heterogeneity and compound heterozygosis give rise to a continuous spectrum of phenylalanine hydroxylase deficiency and metabolic phenotypes in phenylketonuria (PKU). The most used parameters for evaluating phenotype in PKU are pretreatment phenylalanine (Phe) levels, tolerance for dietary Phe, and Phe overloading test. Phenotype can vary from a "classic" (severe) form to mild hyperphenylalaninemia, which does not require dietary treatment. A subset of patients is responsive to treatment by the cofactor tetrahydrobiopterin (BH4 ). Genotypes of PKU patients from Rio de Janeiro, Brazil, were compared to predicted and observed phenotypes. Genotype-based estimations of responsiveness to BH4 were also conducted. METHODS Phenotype was defined by pretreatment Phe levels. A standard prediction system based on arbitrary assigned values was employed to measure genotype-phenotype concordance. Patients were also estimated as BH4 -responders according to the responsiveness previously reported for their mutations and genotypes. RESULTS A 48.3% concordance rate between genotype-predicted and observed phenotypes was found. When the predicted phenotypes included those reported at the BIOPKU database, the concordance rate reached 77%. A total of 18 genotypes from 30 patients (29.4%) were estimated as of potential or probable BH4 responsiveness. Inconsistencies were observed in genotypic combinations including the common "moderate" mutations p.R261Q, p.V388M, and p.I65T and the mild mutations p.L48S, p.R68S, and p.L249F. CONCLUSION The high discordance rate between genotype-predicted and observed metabolic phenotypes in this study seems to be due partially to the high frequency of the so-called "moderate" common mutations, p.R261Q, p.V388M, and p.I65T, which are reported to be associated to erratic or more severe than expected metabolic phenotypes. Although our results of BH4 estimated responsiveness must be regarded as tentative, it should be emphasized that genotyping and genotype-phenotype association studies are important in selecting patients to be offered a BH4 overload test, especially in low-resource settings like Brazil.
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Affiliation(s)
- Eduardo Vieira Neto
- Agência Nacional de Saúde SuplementarGerência de Monitoramento AssistencialRio de JaneiroBrazil
- Serviço de Genética MédicaInstituto de Puericultura e Pediatria Martagão GesteiraUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
| | - Francisco Laranjeira
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Dulce Quelhas
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
- Unidade Multidisciplinar de Investigação BiomédicaUniversidade do PortoPortoPortugal
| | - Isaura Ribeiro
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
- Unidade Multidisciplinar de Investigação BiomédicaUniversidade do PortoPortoPortugal
| | - Alexandre Seabra
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
- Instituto de Ciências Biomédicas Abel SalazarUniversidade do PortoPortoPortugal
| | - Nicole Mineiro
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Lilian M. Carvalho
- Serviço de MetabologiaInstituto Estadual de Diabetes e Endocrinologia Luiz CapriglioneRio de JaneiroBrazil
| | - Lúcia Lacerda
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Márcia G. Ribeiro
- Serviço de Genética MédicaInstituto de Puericultura e Pediatria Martagão GesteiraUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
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Khan CA, Meisburger SP, Ando N, Fitzpatrick PF. The phenylketonuria-associated substitution R68S converts phenylalanine hydroxylase to a constitutively active enzyme but reduces its stability. J Biol Chem 2019; 294:4359-4367. [PMID: 30674554 DOI: 10.1074/jbc.ra118.006477] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 01/15/2019] [Indexed: 11/06/2022] Open
Abstract
The naturally occurring R68S substitution of phenylalanine hydroxylase (PheH) causes phenylketonuria (PKU). However, the molecular basis for how the R68S variant leads to PKU remains unclear. Kinetic characterization of R68S PheH establishes that the enzyme is fully active in the absence of allosteric binding of phenylalanine, in contrast to the WT enzyme. Analytical ultracentrifugation establishes that the isolated regulatory domain of R68S PheH is predominantly monomeric in the absence of phenylalanine and dimerizes in its presence, similar to the regulatory domain of the WT enzyme. Fluorescence and small-angle X-ray scattering analyses establish that the overall conformation of the resting form of R68S PheH is different from that of the WT enzyme. The data are consistent with the substitution disrupting the interface between the catalytic and regulatory domains of the enzyme, shifting the equilibrium between the resting and activated forms ∼200-fold, so that the resting form of R68S PheH is ∼70% in the activated conformation. However, R68S PheH loses activity 2 orders of magnitude more rapidly than the WT enzyme at 37 °C and is significantly more sensitive to proteolysis. We propose that, even though this substitution converts the enzyme to a constitutively active enzyme, it results in PKU because of the decrease in protein stability.
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Affiliation(s)
- Crystal A Khan
- From the Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, Texas 78229 and
| | - Steve P Meisburger
- the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853
| | - Nozomi Ando
- the Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853
| | - Paul F Fitzpatrick
- From the Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, Texas 78229 and
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Genotypes of 2579 patients with phenylketonuria reveal a high rate of BH4 non-responders in Russia. PLoS One 2019; 14:e0211048. [PMID: 30668579 PMCID: PMC6342299 DOI: 10.1371/journal.pone.0211048] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 12/30/2018] [Indexed: 12/12/2022] Open
Abstract
Phenylalanine hydroxylase (PAH) deficiency is responsible for most cases of phenylketonuria (PKU). Furthermore, numerous studies on BH4-sensitive PAH deficiency have been conducted. To date, BH4, a cofactor of PAH, has not been used to treat PKU in Russia.Genotype data of patients with PKU can be used to predict their sensitivity to BH4 therapy. A cohort of 2579 patients with PKU from Russia was analyzed for 25 common PAH gene mutations using custom allele-specific multiplex ligation-dependent probe amplification-based technology. A mutation detection rate of 84.1% chromosomes was accomplished. Both pathogenic alleles were identified in 73.1% of patients. The most frequent pathogenic variants were p.Arg408Trp (50.9%), p.Arg261Gln (5.3%), p.Pro281Leu (3.5%), IVS12+1G>A (3.1%), IVS10-11G>A (2.6%), and p.Arg158Leu (2.4%). The exact boundaries of a PAH exon 5 deletion were defined as EX5del4154ins268 (c.442-2913_509+1173del4154ins268). Severe phenotypes prevailed in the cohort, and classical PKU was observed in 71.8% cases. Due to the genotype-based prediction, 55.9% of the probands were non-responders to the BH4-treatment, and 20.2% were potential responders. Analysis of genotype data is useful to predict BH4 response in PKU patients. The high rate of non-responders among Russian patients was due to the high allele frequency of severe PAH mutations.
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Vieira Neto E, Laranjeira F, Quelhas D, Ribeiro I, Seabra A, Mineiro N, d. M. Carvalho L, Lacerda L, G. Ribeiro M. Mutation analysis of the PAH gene in phenylketonuria patients from Rio de Janeiro, Southeast Brazil. Mol Genet Genomic Med 2018; 6:575-591. [PMID: 29749107 PMCID: PMC6081236 DOI: 10.1002/mgg3.408] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 03/29/2018] [Accepted: 04/06/2018] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Phenylketonuria (PKU) is an autosomal recessive disease resulting from mutations in the PAH gene. Most of the patients are compound heterozygotes, and genotype is a major factor in determining the phenotypic variability of PKU. More than 1,000 variants have been described in the PAH gene. Rio de Janeiro's population has a predominance of Iberian, followed by African and Amerindian ancestries. It is expected that most PKU variants in this Brazilian state have originated in the Iberian Peninsula. However, rare European, African or pathogenic variants that are characteristic of the admixed population of the state might also be found. METHODS A total of 102 patients were included in this study. Genomic DNA was isolated from dried blood spots. Sanger sequencing was used for PAH gene variant identification. Deletions and duplications were also screened using MLPA analysis. Haplotypes were also determined. RESULTS Nine (8.8%) homozygous and 93 (91.2%) compound heterozygous patients were found. The spectrum included 37 causative mutations. Missense, nonsense, and splicing pathogenic variants corresponded to 63.7%, 2.9%, and 22.6% of the mutant alleles, respectively. Large (1.5%), and small deletions, inframe (5.4%) and with frameshift (3.9%), comprised the remainder. The most frequent pathogenic variants were: p.V388M (12.7%), p.R261Q (11.8%), IVS10-11G>A (10.3%), IVS2+5G>C (6.4%), p.S349P (6.4%), p.R252W (5.4%), p.I65T (4.4%), p.T323del (4.4%), and p.P281L (3.4%). One novel variant was detected: c.934G>T (p.G312C) [rs763115697]. CONCLUSION The three most frequent pathogenic variants in our study (34.8% of the alleles) were also the most common in other Brazilian states, Portugal, and Spain (p.V388M, p.R261Q, IVS10-11G>A), corroborating that the Iberian Peninsula is the major source of PAH mutations in Rio de Janeiro. Pathogenic variants that have other geographical origins, such IVS2+5G>C, p.G352Vfs*48, and IVS12+1G>A were also detected. Genetic drift and founder effect may have also played a role in the mutation spectrum we observed.
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Affiliation(s)
- Eduardo Vieira Neto
- Gerência de Monitoramento AssistencialAgência Nacional de Saúde SuplementarRio de JaneiroBrazil
- Serviço de Genética MédicaInstituto de Puericultura e Pediatria Martagão GesteiraUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
| | - Francisco Laranjeira
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Dulce Quelhas
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Isaura Ribeiro
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Alexandre Seabra
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Nicole Mineiro
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Lilian d. M. Carvalho
- Serviço de MetabologiaInstituto de Diabetes e Endocrinologia Luiz CapriglioneRio de JaneiroBrazil
| | - Lúcia Lacerda
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Márcia G. Ribeiro
- Serviço de Genética MédicaInstituto de Puericultura e Pediatria Martagão GesteiraUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
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9
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Jeannesson-Thivisol E, Feillet F, Chéry C, Perrin P, Battaglia-Hsu SF, Herbeth B, Cano A, Barth M, Fouilhoux A, Mention K, Labarthe F, Arnoux JB, Maillot F, Lenaerts C, Dumesnil C, Wagner K, Terral D, Broué P, de Parscau L, Gay C, Kuster A, Bédu A, Besson G, Lamireau D, Odent S, Masurel A, Guéant JL, Namour F. Genotype-phenotype associations in French patients with phenylketonuria and importance of genotype for full assessment of tetrahydrobiopterin responsiveness. Orphanet J Rare Dis 2015; 10:158. [PMID: 26666653 PMCID: PMC5024853 DOI: 10.1186/s13023-015-0375-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 12/08/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mutations in Phenylalanine Hydroxylase (PAH) gene cause phenylketonuria. Sapropterin (BH4), the enzyme cofactor, is an important therapeutical strategy in phenylketonuria. However, PAH is a highly polymorphic gene and it is difficult to identify BH4-responsive genotypes. We seek here to improve prediction of BH4-responsiveness through comparison of genotypes, BH4-loading test, predictions of responsiveness according to the literature and types and locations of mutations. METHODS A total of 364 French patients among which, 9 % had mild hyperphenylalaninemia, 17.7 % mild phenylketonuria and 73.1 % classical phenylketonuria, benefited from a 24-hour BH4-loading test and had the PAH gene sequenced and analyzed by Multiplex Ligation Probe Amplification. RESULTS Overall, 31.6 % of patients were BH4-responsive. The number of different mutations found was 127, including 26 new mutations. The mutations c.434A > T, c.500A > T, c.529G > C, c.1045 T > G and c.1196 T > C were newly classified as being BH4-responsive. We identified 261 genotypes, among which 46 were newly recognized as being BH4-responsive. Even though patients carry 2 responsive alleles, BH4-responsiveness cannot be predicted with certainty unless they present mild hyperphenylalaninemia. BH4-responsiveness cannot be predicted in patients carrying one responsive mutation only. In general, the milder the phenotype is, the stronger the BH4-response is. Almost exclusively missense mutations, particularly in exons 12, 11 and 8, are associated with BH4-responsiveness and any other type of mutation predicts a negative response. CONCLUSIONS This study is the first of its kind, in a French population, to identify the phenotype associated with several combinations of PAH mutations. As others, it highlights the necessity of performing simultaneously BH4 loading test and molecular analysis in monitoring phenylketonuria patients.
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Affiliation(s)
- Elise Jeannesson-Thivisol
- Reference Center for Inherited Metabolic Diseases, University Hospital of Nancy, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
- INSERM U954, Department of Nutrition-Genetics-Environmental Risk Exposure, University of Lorraine, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
| | - François Feillet
- Reference Center for Inherited Metabolic Diseases, University Hospital of Nancy, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
- INSERM U954, Department of Nutrition-Genetics-Environmental Risk Exposure, University of Lorraine, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
| | - Céline Chéry
- Reference Center for Inherited Metabolic Diseases, University Hospital of Nancy, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
- INSERM U954, Department of Nutrition-Genetics-Environmental Risk Exposure, University of Lorraine, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
| | - Pascal Perrin
- Reference Center for Inherited Metabolic Diseases, University Hospital of Nancy, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
- INSERM U954, Department of Nutrition-Genetics-Environmental Risk Exposure, University of Lorraine, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
| | - Shyue-Fang Battaglia-Hsu
- Reference Center for Inherited Metabolic Diseases, University Hospital of Nancy, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
- INSERM U954, Department of Nutrition-Genetics-Environmental Risk Exposure, University of Lorraine, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
| | - Bernard Herbeth
- Reference Center for Inherited Metabolic Diseases, University Hospital of Nancy, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
- INSERM U954, Department of Nutrition-Genetics-Environmental Risk Exposure, University of Lorraine, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
| | - Aline Cano
- Reference Center for Inherited Metabolic Diseases, Timone Hospital, Marseille, France
| | - Magalie Barth
- Department of Biochemistry and Genetics, Angers University Hospital, Angers, France
| | - Alain Fouilhoux
- Reference Center for Inherited Metabolic Diseases, Hospices Civils de Lyon, Bron, France
| | - Karine Mention
- Reference Center for Inherited Metabolic Diseases, Jeanne de Flandres Hospital, Lille, France
| | - François Labarthe
- Department of Pediatric Medicine, Clocheville Hospital, Tours, France
| | - Jean-Baptiste Arnoux
- Reference Center for Inherited Metabolic Diseases, Necker-Enfants Malades Hospital, Paris, France
| | - François Maillot
- Department of Internal Medicine, Tours University Hospital, Tours, France
| | | | - Cécile Dumesnil
- Pediatric Hematology and Oncology, Rouen University-Hospital, Rouen, France
| | - Kathy Wagner
- Department of Pediatrics, Lenval Hospital, Nice, France
| | - Daniel Terral
- Department of Pediatrics, Hotel-Dieu Hospital, Clermont-Ferrand, France
| | - Pierre Broué
- Department of Pediatric Hepatology and Metabolic Diseases, Children Hospital, Toulouse, France
| | | | - Claire Gay
- Department of Pediatrics, Saint-Etienne University-Hospital, Saint-Etienne, France
| | - Alice Kuster
- Pediatric Department, Nantes University Hospital, Nantes, France
| | - Antoine Bédu
- Neonatology Department, Mère-Enfant Hospital, Limoges, France
| | - Gérard Besson
- Department of Neurology, University Hospital of Grenoble, Grenoble, France
| | - Delphine Lamireau
- Department of Pediatrics, Pellegrin-Enfants Hospital, Bordeaux, France
| | - Sylvie Odent
- Department of Clinical Genetics, Rennes University Hospital, Rennes, France
| | - Alice Masurel
- Department of Medical Genetics, Dijon University-Hospital, Dijon, France
| | - Jean-Louis Guéant
- Reference Center for Inherited Metabolic Diseases, University Hospital of Nancy, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
- INSERM U954, Department of Nutrition-Genetics-Environmental Risk Exposure, University of Lorraine, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France
| | - Fares Namour
- Reference Center for Inherited Metabolic Diseases, University Hospital of Nancy, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France.
- INSERM U954, Department of Nutrition-Genetics-Environmental Risk Exposure, University of Lorraine, 9 ave Forêt de Haye, BP 184, 54511, Vandoeuvre-lès-Nancy, France.
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Tao J, Li N, Jia H, Liu Z, Li X, Song J, Deng Y, Jin X, Zhu J. Correlation between genotype and the tetrahydrobiopterin-responsive phenotype in Chinese patients with phenylketonuria. Pediatr Res 2015; 78:691-9. [PMID: 26322415 PMCID: PMC4700046 DOI: 10.1038/pr.2015.167] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 06/17/2015] [Indexed: 01/30/2023]
Abstract
BACKGROUND A growing body of research has suggested that tetrahydrobiopterin (BH4) responsive phenotype can be predicted by the phenylalanine hydroxylase (PAH) genotype in patients with phenylketonuria (PKU), but data concerning the association between genotype and BH4 responsiveness are scarce in China. METHODS A total of 165 PKU patients from China who had undergone a 24-h loading test with BH4 administration were recruited. Genotyping was performed by the next-generation sequencing (NGS) technique. Using the predicted residual PAH activity, we analyzed the association between genotype and BH4-responsiveness. RESULTS Among the 165 patients, 40 patients (24.24%) responded to BH4. A total of 74 distinct mutations were observed, including 13 novel mutations. The mutation p.R241C was most frequently associated with response. Two known mutations (p.A322T and p.Q419R) and two novel mutations (p.L98V and IVS3-2A>T) were first reported as responsive to BH4. Residual PAH activity of at least 12.5% was needed for responsive genotypes. CONCLUSION Genotype-based predictions of BH4-responsiveness are only for selecting potential responders. Accordingly, it is necessary to test potential responders with a long-term BH4 challenge.
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Affiliation(s)
- Jing Tao
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- West China School of Public Health, Sichuan University, Sichuan, China
| | - Nana Li
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- Laboratory of Molecular Epidemiology for Birth Defects, West China Second University Hospital, Sichuan University, Sichuan, China
| | - Haitao Jia
- BGI-Shenzhen, Shenzhen, Guangdong, China
| | - Zhen Liu
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- Laboratory of Molecular Epidemiology for Birth Defects, West China Second University Hospital, Sichuan University, Sichuan, China
| | - Xiaohong Li
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- Laboratory of Molecular Epidemiology for Birth Defects, West China Second University Hospital, Sichuan University, Sichuan, China
| | | | - Ying Deng
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- Laboratory of Molecular Epidemiology for Birth Defects, West China Second University Hospital, Sichuan University, Sichuan, China
| | - Xi Jin
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
- Laboratory of Molecular Epidemiology for Birth Defects, West China Second University Hospital, Sichuan University, Sichuan, China
| | - Jun Zhu
- National Centre for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Sichuan, China
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11
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Biglari A, Saffari F, Rashvand Z, Alizadeh S, Najafipour R, Sahmani M. Mutations of the phenylalanine hydroxylase gene in Iranian patients with phenylketonuria. SPRINGERPLUS 2015; 4:542. [PMID: 26413448 PMCID: PMC4579200 DOI: 10.1186/s40064-015-1309-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 09/04/2015] [Indexed: 11/30/2022]
Abstract
Phenylketonuria (PKU) is an autosomal recessive disease which results from mutations in the phenylalanine hydroxylase (PAH) gene. The aim of this study was the identification of sixteen different mutations in Iranian patients with hyperphenylalaninemia. The mutations were detected during the characterization of PAH genotypes of 39 PKU patients from Qazvin and Zanjan provinces of Iran. PAH mutations have been analyzed by PCR and direct sequencing of PCR products of the promoter region and all 13 exons of PAH gene, including the splicing sites. A mutation detection rate of 74.3 % was realized. Two mutations were found at high frequencies: R176X (10.25 %) and p.P281L (10.25 %). The frequencies of the other mutations were: IVS2+5G>A (2.56 %), IVS2+5G>C (2.56 %), p.L48S (2.56 %), p.R243Q (2.56 %), p.R252Q (5.12 %), p.R261Q (7.69 %), p.R261X (5.12 %), p.E280K (2.56 %), p.I283N (2.56 %), IVS9+5G>A (2.56 %), IVS9+1G>A (1.28 %), IVS11+1G>C (1.28 %), p.C357R (1.28 %), c.632delC (2.56 %). The present results confirm the high heterogeneity of the PAH locus and contribute to information about the distribution and frequency of PKU mutations in the Iranian population.
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Affiliation(s)
- Alireza Biglari
- Department of Molecular Medicine and Genetics, School of Medicine, Zanjan University of Medical Sciences, Zanjan, Iran
| | - Fatemeh Saffari
- Department of Pediatrics, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Zahra Rashvand
- Faculty of Medicine, The Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Safarali Alizadeh
- Faculty of Medicine, The Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Reza Najafipour
- Department of Clinical Biochemistry and Genetics, Faculty of Medicine, Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Mehdi Sahmani
- Department of Clinical Biochemistry and Genetics, Faculty of Medicine, Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
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12
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Camp KM, Parisi MA, Acosta PB, Berry GT, Bilder DA, Blau N, Bodamer OA, Brosco JP, Brown CS, Burlina AB, Burton BK, Chang CS, Coates PM, Cunningham AC, Dobrowolski SF, Ferguson JH, Franklin TD, Frazier DM, Grange DK, Greene CL, Groft SC, Harding CO, Howell RR, Huntington KL, Hyatt-Knorr HD, Jevaji IP, Levy HL, Lichter-Konecki U, Lindegren ML, Lloyd-Puryear MA, Matalon K, MacDonald A, McPheeters ML, Mitchell JJ, Mofidi S, Moseley KD, Mueller CM, Mulberg AE, Nerurkar LS, Ogata BN, Pariser AR, Prasad S, Pridjian G, Rasmussen SA, Reddy UM, Rohr FJ, Singh RH, Sirrs SM, Stremer SE, Tagle DA, Thompson SM, Urv TK, Utz JR, van Spronsen F, Vockley J, Waisbren SE, Weglicki LS, White DA, Whitley CB, Wilfond BS, Yannicelli S, Young JM. Phenylketonuria Scientific Review Conference: state of the science and future research needs. Mol Genet Metab 2014; 112:87-122. [PMID: 24667081 DOI: 10.1016/j.ymgme.2014.02.013] [Citation(s) in RCA: 133] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 02/25/2014] [Accepted: 02/26/2014] [Indexed: 01/17/2023]
Abstract
New developments in the treatment and management of phenylketonuria (PKU) as well as advances in molecular testing have emerged since the National Institutes of Health 2000 PKU Consensus Statement was released. An NIH State-of-the-Science Conference was convened in 2012 to address new findings, particularly the use of the medication sapropterin to treat some individuals with PKU, and to develop a research agenda. Prior to the 2012 conference, five working groups of experts and public members met over a 1-year period. The working groups addressed the following: long-term outcomes and management across the lifespan; PKU and pregnancy; diet control and management; pharmacologic interventions; and molecular testing, new technologies, and epidemiologic considerations. In a parallel and independent activity, an Evidence-based Practice Center supported by the Agency for Healthcare Research and Quality conducted a systematic review of adjuvant treatments for PKU; its conclusions were presented at the conference. The conference included the findings of the working groups, panel discussions from industry and international perspectives, and presentations on topics such as emerging treatments for PKU, transitioning to adult care, and the U.S. Food and Drug Administration regulatory perspective. Over 85 experts participated in the conference through information gathering and/or as presenters during the conference, and they reached several important conclusions. The most serious neurological impairments in PKU are preventable with current dietary treatment approaches. However, a variety of more subtle physical, cognitive, and behavioral consequences of even well-controlled PKU are now recognized. The best outcomes in maternal PKU occur when blood phenylalanine (Phe) concentrations are maintained between 120 and 360 μmol/L before and during pregnancy. The dietary management treatment goal for individuals with PKU is a blood Phe concentration between 120 and 360 μmol/L. The use of genotype information in the newborn period may yield valuable insights about the severity of the condition for infants diagnosed before maximal Phe levels are achieved. While emerging and established genotype-phenotype correlations may transform our understanding of PKU, establishing correlations with intellectual outcomes is more challenging. Regarding the use of sapropterin in PKU, there are significant gaps in predicting response to treatment; at least half of those with PKU will have either minimal or no response. A coordinated approach to PKU treatment improves long-term outcomes for those with PKU and facilitates the conduct of research to improve diagnosis and treatment. New drugs that are safe, efficacious, and impact a larger proportion of individuals with PKU are needed. However, it is imperative that treatment guidelines and the decision processes for determining access to treatments be tied to a solid evidence base with rigorous standards for robust and consistent data collection. The process that preceded the PKU State-of-the-Science Conference, the conference itself, and the identification of a research agenda have facilitated the development of clinical practice guidelines by professional organizations and serve as a model for other inborn errors of metabolism.
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Affiliation(s)
- Kathryn M Camp
- Office of Dietary Supplements, National Institutes of Health, Bethesda, MD 20982, USA.
| | - Melissa A Parisi
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
| | | | - Gerard T Berry
- Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | - Deborah A Bilder
- Department of Psychiatry, University of Utah, Salt Lake City, UT 84108, USA.
| | - Nenad Blau
- University Children's Hospital, Heidelberg, Germany; University Children's Hospital, Zürich, Switzerland.
| | - Olaf A Bodamer
- University of Miami Miller School of Medicine, Miami, FL 33136, USA.
| | - Jeffrey P Brosco
- University of Miami Mailman Center for Child Development, Miami, FL 33101, USA.
| | | | | | - Barbara K Burton
- Ann and Robert H. Lurie Children's Hospital of Chicago, Chicago, IL 60611, USA.
| | - Christine S Chang
- Agency for Healthcare Research and Quality, Rockville, MD 20850, USA.
| | - Paul M Coates
- Office of Dietary Supplements, National Institutes of Health, Bethesda, MD 20982, USA.
| | - Amy C Cunningham
- Tulane University Medical School, Hayward Genetics Center, New Orleans, LA 70112, USA.
| | | | - John H Ferguson
- Office of Rare Diseases Research, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20982, USA.
| | | | | | - Dorothy K Grange
- Washington University School of Medicine, St. Louis Children's Hospital, St. Louis, MO 63110, USA.
| | - Carol L Greene
- University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - Stephen C Groft
- Office of Rare Diseases Research, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20982, USA.
| | - Cary O Harding
- Oregon Health & Science University, Portland, OR 97239, USA.
| | - R Rodney Howell
- University of Miami Miller School of Medicine, Miami, FL 33136, USA.
| | | | - Henrietta D Hyatt-Knorr
- Office of Rare Diseases Research, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20982, USA.
| | - Indira P Jevaji
- Office of Research on Women's Health, National Institutes of Health, Bethesda, MD 20817, USA.
| | - Harvey L Levy
- Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | - Uta Lichter-Konecki
- George Washington University, Children's National Medical Center, Washington, DC 20010, USA.
| | | | | | | | | | - Melissa L McPheeters
- Vanderbilt Evidence-based Practice Center, Institute for Medicine and Public Health, Nashville, TN 37203, USA.
| | - John J Mitchell
- McGill University Health Center, Montreal, Quebec H3H 1P3, Canada.
| | - Shideh Mofidi
- Maria Fareri Children's Hospital of Westchester Medical Center, Valhalla, NY 10595, USA.
| | - Kathryn D Moseley
- University of Southern California Keck School of Medicine, Los Angeles, CA 90033, USA.
| | - Christine M Mueller
- Office of Orphan Products Development, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA.
| | - Andrew E Mulberg
- Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA.
| | - Lata S Nerurkar
- Office of Rare Diseases Research, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20982, USA.
| | - Beth N Ogata
- University of Washington, Seattle, WA 98195, USA.
| | - Anne R Pariser
- Center for Drug Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA.
| | - Suyash Prasad
- BioMarin Pharmaceutical Inc., San Rafael, CA 94901, USA.
| | - Gabriella Pridjian
- Tulane University Medical School, Hayward Genetics Center, New Orleans, LA 70112, USA.
| | | | - Uma M Reddy
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
| | | | | | - Sandra M Sirrs
- Vancouver General Hospital, University of British Columbia, Vancouver V5Z 1M9, Canada.
| | | | - Danilo A Tagle
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Susan M Thompson
- The Children's Hospital at Westmead, Sydney, NSW 2145, Australia.
| | - Tiina K Urv
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Jeanine R Utz
- University of Minnesota, Minneapolis, MN 55455, USA.
| | - Francjan van Spronsen
- University of Groningen, University Medical Center of Groningen, Beatrix Children's Hospital, Netherlands.
| | - Jerry Vockley
- University of Pittsburgh, Pittsburgh, PA 15224, USA.
| | - Susan E Waisbren
- Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | - Linda S Weglicki
- National Institute of Nursing Research, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Desirée A White
- Department of Psychology, Washington University, St. Louis, MO 63130, USA.
| | | | - Benjamin S Wilfond
- Seattle Children's Research Institute, University of Washington School of Medicine, Seattle, WA 98101, USA.
| | | | - Justin M Young
- The Young Face, Facial Plastic and Reconstructive Surgery, Cumming, GA 30041, USA.
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Intra-familiar discordant PKU phenotype explained by mutation analysis in three pedigrees. Clin Biochem 2013; 47:233-5. [PMID: 24296287 DOI: 10.1016/j.clinbiochem.2013.11.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Revised: 11/16/2013] [Accepted: 11/19/2013] [Indexed: 11/23/2022]
Abstract
Classical phenylketonuria (PKU) and mild hyperphenylalaninemia (MHP) are two phenotypes of phenylalanine hydroxylase (PAH) deficiency with different degrees of severity. We have analyzed three families in which classical PKU, MHP and a normal phenotype occurred within each family due to the different combinations of three mutations segregating within the family. Indeed, sequence PAH analysis revealed three different alleles segregating in each family. This report suggests that when discordant phenotypes occur in a family, complete analysis of the PAH gene may be performed in order to support the diagnosis and assist in accurate genetic counseling and patient management. We further support the marked heterogeneity of hyperphenylalaninemia primarily due to allelic heterogeneity at the PAH locus.
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Zhu T, Ye J, Han L, Qiu W, Zhang H, Liang L, Gu X. Variations in genotype–phenotype correlations in phenylalanine hydroxylase deficiency in Chinese Han population. Gene 2013; 529:80-7. [DOI: 10.1016/j.gene.2013.07.079] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 07/19/2013] [Accepted: 07/22/2013] [Indexed: 11/16/2022]
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Abstract
INTRODUCTION Phenylketonuria (PKU) is caused by mutation of the enzyme, phenylalanine (Phe) hydroxylase (PAH). The hyperphenylalaninemia characteristic of PKU causes devastating neurological damage if not identified and treated at birth with a Phe-restricted diet. Sapropterin dihydrochloride, a pharmaceutical formulation of the natural cofactor for PAH (6R-tetrahydrobiopterin; BH4), is now available for the management of hyperphenylalaninemia in some PKU patients, including BH4 deficiencies. Sapropterin dihydrochloride improves dietary Phe tolerance in about 20% of patients with PKU. AREAS COVERED This evaluation describes the identification of patients suitable for treatment of sapropterin dihydrochloride, together with its indications, therapeutic properties and efficacy. Furthermore, the article reviews its safety and tolerability in patients with PKU or BH4 deficiency. EXPERT OPINION A reduction in blood Phe of at least 30% occurred in ∼ 20 - 30% of sapropterin-treated PKU patients (mostly with milder forms of PKU). Treatment with sapropterin resulted in clinically significant and sustained reductions in blood Phe concentrations and increased dietary Phe tolerance in well-designed clinical studies in PKU patients who responded to BH4. Successful treatment with sapropterin may lead to a relaxation of the Phe-restricted diet, although continued monitoring of blood Phe is required. Sapropterin was well tolerated.
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Affiliation(s)
- Nenad Blau
- University Children's Hospital, Division of Inborn Metabolic Diseases, Department of General Pediatrics, Im Neuenheimer Feld 430, 69120 Heidelberg, Germany.
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