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Bonfim‐Freitas PE, Andrade RS, Ribeiro‐dos‐Santos ÂK, Silva LCS. Molecular characterization of phenylketonuria patients from the North Region of Brazil: State of Pará. Mol Genet Genomic Med 2023; 11:e2224. [PMID: 37421234 PMCID: PMC10568386 DOI: 10.1002/mgg3.2224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/23/2023] [Indexed: 07/10/2023] Open
Abstract
BACKGROUND Phenylketonuria (PKU) is an autosomal recessive disease resulting from a deficiency of the enzyme phenylalanine hydroxylase (PAH). Hyperphenylalaninemias (HPA) due to PAH deficiency are accompanied by a wide variety of clinical, biochemical, and molecular features. To identify and characterize pathogenic variants in the PAH gene and establish a correlation between genotype and biochemical phenotype in patients with PKU from state of Pará in the North Region of Brazil. METHODS All 13 exons of the PAH gene from 32 patients (21 PKU and 11 non-PKU HPA) were amplified by PCR and submitted to DNA sequencing (Sanger). Biochemical data were obtained from the patients' medical records. RESULTS Molecular analysis identified 17 pathogenic variants and 3 nonpathogenic variants. The most frequent pathogenic variants were IVS10-11G>A (7.9%), p. Arg261Gln (7.9%), p. Val388Met (6.3%) and p. Ile65Thr (4.7%). Was observed correlations and inconsistencies between genotype and biochemical phenotype. CONCLUSION In PKU patients from state of Pará, North Region of Brazil, a heterogeneous mutation spectrum was revealed, in which the most frequent mutations are variants commonly observed in other Brazilian studies and in the region of the Iberian Peninsula.
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Affiliation(s)
- Pedro E. Bonfim‐Freitas
- Laboratory of Inborn Errors of MetabolismInstitute of Biological Sciences, Federal University of ParáBelémBrazil
- Present address:
Hepatology DepartmentEvandro Chagas InstituteBelémPABrazil
| | - Roseani S. Andrade
- Faculty of NutritionInstitute of Health Sciences, Federal University of ParáBelémBrazil
| | | | - Luiz C. Santana‐da Silva
- Laboratory of Inborn Errors of MetabolismInstitute of Biological Sciences, Federal University of ParáBelémBrazil
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Ferreira F, Azevedo L, Neiva R, Sousa C, Fonseca H, Marcão A, Rocha H, Carmona C, Ramos S, Bandeira A, Martins E, Campos T, Rodrigues E, Garcia P, Diogo L, Ferreira AC, Sequeira S, Silva F, Rodrigues L, Gaspar A, Janeiro P, Amorim A, Vilarinho L. Phenylketonuria in Portugal: Genotype-phenotype correlations using molecular, biochemical, and haplotypic analyses. Mol Genet Genomic Med 2021; 9:e1559. [PMID: 33465300 PMCID: PMC8104178 DOI: 10.1002/mgg3.1559] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/29/2020] [Indexed: 11/12/2022] Open
Abstract
Background The impairment of the hepatic enzyme phenylalanine hydroxylase (PAH) causes elevation of phenylalanine levels in blood and other body fluids resulting in the most common inborn error of amino acid metabolism (phenylketonuria). Persistently high levels of phenylalanine lead to irreversible damage to the nervous system. Therefore, early diagnosis of the affected individuals is important, as it can prevent clinical manifestations of the disease. Methods In this report, the biochemical and genetic findings performed in 223 patients diagnosed through the Portuguese Neonatal Screening Program (PNSP) are presented. Results Overall, the results show that a high overlap exists between different types of variants and phenylalanine levels. Molecular analyses reveal a wide mutational spectrum in our population with a total of 56 previously reported variants, most of them found in compound heterozygosity (74% of the patients). Intragenic polymorphic markers were used to assess the haplotypic structure of mutated chromosomes for the most frequent variants found in homozygosity in our population (p.Ile65Thr, p.Arg158Gln, p.Leu249Phe, p.Arg261Gln, p.Val388Met, and c.1066‐11G>A). Conclusion Our data reveal high heterogeneity at the biochemical and molecular levels and are expected to provide a better understanding of the molecular basis of this disease and to provide clues to elucidate genotype–phenotype correlations.
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Affiliation(s)
- Filipa Ferreira
- Newborn Screening, Metabolic and Genetics Unit, Department of Human Genetics, National Institute of Health Dr Ricardo Jorge, Porto, Portugal
| | - Luísa Azevedo
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal.,FCUP - Faculty of Sciences, University of Porto, Porto, Portugal
| | - Raquel Neiva
- Newborn Screening, Metabolic and Genetics Unit, Department of Human Genetics, National Institute of Health Dr Ricardo Jorge, Porto, Portugal
| | - Carmen Sousa
- Newborn Screening, Metabolic and Genetics Unit, Department of Human Genetics, National Institute of Health Dr Ricardo Jorge, Porto, Portugal
| | - Helena Fonseca
- Newborn Screening, Metabolic and Genetics Unit, Department of Human Genetics, National Institute of Health Dr Ricardo Jorge, Porto, Portugal
| | - Ana Marcão
- Newborn Screening, Metabolic and Genetics Unit, Department of Human Genetics, National Institute of Health Dr Ricardo Jorge, Porto, Portugal
| | - Hugo Rocha
- Newborn Screening, Metabolic and Genetics Unit, Department of Human Genetics, National Institute of Health Dr Ricardo Jorge, Porto, Portugal
| | - Célia Carmona
- Newborn Screening, Metabolic and Genetics Unit, Department of Human Genetics, National Institute of Health Dr Ricardo Jorge, Porto, Portugal
| | - Sónia Ramos
- Newborn Screening, Metabolic and Genetics Unit, Department of Human Genetics, National Institute of Health Dr Ricardo Jorge, Porto, Portugal
| | - Anabela Bandeira
- Inherited Metabolic Disease Reference Center, Pediatric Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Esmeralda Martins
- Inherited Metabolic Disease Reference Center, Pediatric Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Teresa Campos
- Metabolic Diseases Unit, Pediatric Department, University Center São João Hospital - HSJ, Porto, Portugal
| | - Esmeralda Rodrigues
- Metabolic Diseases Unit, Pediatric Department, University Center São João Hospital - HSJ, Porto, Portugal
| | - Paula Garcia
- Inherited Metabolic Disease Reference Center, Pediatric Hospital, Hospital and University Center of Coimbra, Coimbra, Portugal
| | - Luísa Diogo
- Inherited Metabolic Disease Reference Center, Pediatric Hospital, Hospital and University Center of Coimbra, Coimbra, Portugal
| | - Ana Cristina Ferreira
- Metabolic Unit, Hospital Dona Estefânia, Centro Hospitalar Universitário Lisboa Central, Lisbon, Portugal
| | - Silvia Sequeira
- Metabolic Unit, Hospital Dona Estefânia, Centro Hospitalar Universitário Lisboa Central, Lisbon, Portugal
| | - Francisco Silva
- Pediatric Department, Hospital Central of Funchal, Funchal, Portugal
| | - Luísa Rodrigues
- Pediatrics Department, Hospital of Divino Espírito Santo of Ponta Delgada, EPE, Ponta Delgada, Azores, Portugal
| | - Ana Gaspar
- Inherited Metabolic Disease Reference Center, Lisbon North University Hospital Center (CHULN), EPE, Lisboa, Portugal
| | - Patrícia Janeiro
- Inherited Metabolic Disease Reference Center, Lisbon North University Hospital Center (CHULN), EPE, Lisboa, Portugal
| | - António Amorim
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IPATIMUP - Instituto de Patologia e Imunologia Molecular da Universidade do Porto, Porto, Portugal.,FCUP - Faculty of Sciences, University of Porto, Porto, Portugal
| | - Laura Vilarinho
- Newborn Screening, Metabolic and Genetics Unit, Department of Human Genetics, National Institute of Health Dr Ricardo Jorge, Porto, Portugal.,Research and Development Unit, Department of Human Genetics, National Institute of Health Dr Ricardo Jorge, Porto, Portugal
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Molecular-genetic causes for the high frequency of phenylketonuria in the population from the North Caucasus. PLoS One 2018; 13:e0201489. [PMID: 30067850 PMCID: PMC6070269 DOI: 10.1371/journal.pone.0201489] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 07/15/2018] [Indexed: 01/25/2023] Open
Abstract
Phenylketonuria is an inherited disease caused by mutations in the phenylalanine hydroxylase gene PAH. Different PAH pathogenic variants occur in different ethnic groups with various frequencies and the incidence of the disease itself varies from country to country. In the Caucasus region of Russia, some ethnoses are geographically and culturally isolated from each other. The tradition of monoethnic marriages may cause decreased genetic variability in those populations. In the Karachay-Cherkess Republic (Russia), the highest incidence of phenylketonuria in the world has been detected (1:850 newborns) in the region and 1:332 among the titular nation Karachays. Here, we showed that this phenomenon is due to the widespread prevalence of the p.Arg261* variant. Its allele frequency among Karachay patients with PKU was 68.4% and the carrier frequency in Karachays was 1:16 healthy individuals. PAH haplotype analysis showed a unique common origin. The founder haplotype and mutation "age" were estimated by analyzing the linkage disequilibrium between p.Arg261* and extragenic short tandem repeat loci. The p.Arg261* variant occurred in the Karachays population 10.2 ± 2.7 generations ago (275 ± 73 years) and its spread occurred in parallel with the growth of the population.
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Zinchenko RA, Makaov AK, Kadyshev VV, Galkina VA, Dadali EL, Shurygina MF, El’chinova GI, Mikhailova LK, Marakhonov AV, Vasilyeva TA, Petrova NV, Gundorova P, Tanas AS, Strelnikov VV, Polyakov AV, Ginter EK. Medical Genetic Study of Hereditary Diseases in Abazins of the Karachay-Cherkess Republic. RUSS J GENET+ 2018. [DOI: 10.1134/s1022795418060170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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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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Razipour M, Alavinejad E, Sajedi SZ, Talebi S, Entezam M, Mohajer N, Kazemi-Sefat GE, Gharesouran J, Setoodeh A, Mohaddes Ardebili SM, Keramatipour M. Genetic study of the PAH locus in the Iranian population: familial gene mutations and minihaplotypes. Metab Brain Dis 2017; 32:1685-1691. [PMID: 28676969 DOI: 10.1007/s11011-017-0048-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 06/02/2017] [Indexed: 01/17/2023]
Abstract
Phenylketonuria (PKU), one of the most common inborn errors of amino acid metabolism, is caused by mutations in the phenylalanine hydroxylase (PAH) gene (PAH). PKU has wide allelic heterogeneity, and over 600 different disease-causing mutations in PAH have been detected to date. Up to now, there have been no reports on the minihaplotype (VNTR/STR) analysis of PAH locus in the Iranian population. The aims of the present study were to determine PAH mutations and minihaplotypes in Iranian families with PAH deficiency and to investigate the correlation between them. A total of 81 Iranian families with PAH deficiency were examined using PCR-sequencing of all 13 PAH exons and their flanking intron regions to identify sequence variations. Fragment analysis of the PAH minihaplotypes was performed by capillary electrophoresis for 59 families. In our study, 33 different mutations were found accounting for 95% of the total mutant alleles. The majority of these mutations (72%) were distributed across exons 7, 11, 2 and their flanking intronic regions. Mutation c.1066-11G > A was the most common with a frequency of 20.37%. The less frequent mutations, p.Arg261Gln (8%), p.Arg243Ter (7.4%), p.Leu48Ser (7.4%), p.Lys363Asnfs*37 (6.79%), c.969 + 5G > A (6.17%), p.Pro281Leu (5.56), c.168 + 5G > C (5.56), and p.Arg261Ter (4.94) together comprised about 52% of all mutant alleles. In this study, a total of seventeen PAH gene minihaplotypes were detected, six of which associated exclusively with particular mutations. Our findings indicate a broad PAH mutation spectrum in the Iranian population, which is consistent with previous studies reporting a wide range of PAH mutations, most likely due to ethnic heterogeneity. High prevalence of c.1066-11G > A mutation linked to minihaplotype 7/250 among both Iranian and Mediterranean populations is indicative of historical and geographical links between them. Also, strong association between particular mutations and minihaplotypes could be useful for prenatal diagnosis (PND) and preimplantation genetic diagnosis (PGD) in affected families.
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Affiliation(s)
- Masoumeh Razipour
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Elaheh Alavinejad
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyede Zahra Sajedi
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
- Department of Medical Genetics, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Saeed Talebi
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Mona Entezam
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Neda Mohajer
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Golnaz-Ensieh Kazemi-Sefat
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Department of Molecular Medicine, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Jalal Gharesouran
- Department of Medical Genetics, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Aria Setoodeh
- Department of Endocrinology, Children's Hospital Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Seyyed Mojtaba Mohaddes Ardebili
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
- Department of Medical Genetics, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Mohammad Keramatipour
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
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7
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Gundorova P, Zinchenko RA, Makaov AK, Polyakov AV. The spectrum of mutations in the PAH gene in patients with hyperphenylalaninemia from the Karachay-Cherkess Republic. RUSS J GENET+ 2017. [DOI: 10.1134/s1022795417070043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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8
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Gundorova P, Stepanova AA, Makaov AK, Zinchenko RA, Abaykhanova ZM, Polyakov AV. Mutation spectrum of the PAH gene in phenylketonuria patients in the Karachay-Cherkess Republic (Russia). RUSS J GENET+ 2016. [DOI: 10.1134/s1022795416110041] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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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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Coelho AI, Ramos R, Gaspar A, Costa C, Oliveira A, Diogo L, Garcia P, Paiva S, Martins E, Teles EL, Rodrigues E, Cardoso MT, Ferreira E, Sequeira S, Leite M, Silva MJ, de Almeida IT, Vicente JB, Rivera I. A frequent splicing mutation and novel missense mutations color the updated mutational spectrum of classic galactosemia in Portugal. J Inherit Metab Dis 2014; 37:43-52. [PMID: 23749220 DOI: 10.1007/s10545-013-9623-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 05/16/2013] [Accepted: 05/17/2013] [Indexed: 01/28/2023]
Abstract
Classic galactosemia is an autosomal recessive disorder caused by deficient galactose-1-phosphate uridylyltransferase (GALT) activity. Patients develop symptoms in the neonatal period, which can be ameliorated by dietary restriction of galactose. Many patients develop long-term complications, with a broad range of clinical symptoms whose pathophysiology is poorly understood. The high allelic heterogeneity of GALT gene that characterizes this disorder is thought to play a determinant role in biochemical and clinical phenotypes. We aimed to characterize the mutational spectrum of GALT deficiency in Portugal and to assess potential genotype-phenotype correlations. Direct sequencing of the GALT gene and in silico analyses were employed to evaluate the impact of uncharacterized mutations upon GALT functionality. Molecular characterization of 42 galactosemic Portuguese patients revealed a mutational spectrum comprising 14 nucleotide substitutions: ten missense, two nonsense and two putative splicing mutations. Sixteen different genotypic combinations were detected, half of the patients being p.Q188R homozygotes. Notably, the second most frequent variation is a splicing mutation. In silico predictions complemented by a close-up on the mutations in the protein structure suggest that uncharacterized missense mutations have cumulative point effects on protein stability, oligomeric state, or substrate binding. One splicing mutation is predicted to cause an alternative splicing event. This study reinforces the difficulty in establishing a genotype-phenotype correlation in classic galactosemia, a monogenic disease whose complex pathogenesis and clinical features emphasize the need to expand the knowledge on this "cloudy" disorder.
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Affiliation(s)
- Ana I Coelho
- Metabolism & Genetics Group, Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculty of Pharmacy, University of Lisbon, Av. Prof. Gama Pinto, 1643-009, Lisbon, Portugal
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11
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Moradi K, Alibakhshi R, Ghadiri K, Khatami SR, Galehdari H. Molecular analysis of exons 6 and 7 of phenylalanine hydroxylase gene mutations in Phenylketonuria patients in Western Iran. INDIAN JOURNAL OF HUMAN GENETICS 2013; 18:290-3. [PMID: 23716935 PMCID: PMC3656516 DOI: 10.4103/0971-6866.107978] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND: Phenylketonuria (PKU) is an inborn error of amino acid metabolism that results from a deficiency of phenylalanine hydroxylase (PAH). According to PAH database, exons 6 and 7 and their flanking introns of PAH gene contain the greatest number of mutant alleles. Therefore, as a preliminary study, nucleotide sequence analysis of exons 6 and 7 of the PAH gene has been performed in 25 PKU patients whose ancestors lived in Kermanshah province of Iran. To date, there has been no mutation data describing the genotypes of the PKU disease in this Kurdish ethnic region background. MATERIALS AND METHODS: Twenty-five patients (aged between 2 and 23 years) participated in this study. The DNA fragments containing two exons of the PAH gene [6 and 7] and their exon-flanking intronic sequences were amplified and sequenced. RESULTS: The total of detected mutations were R261X (8%), R176X (4%), R243Q (4%), R243X (2%) and R261Q (2%), as they accounted for 20% of all mutant alleles in this study. The identified polymorphisms are: IVS5 -54 G > A (22%), Q232Q (8%) and V245V (4%). All of the detected mutations in this study are related to CpG dinucleotides in the PAH gene sequence. CONCLUSION: The frequency of R261X, the most common mutation in our study, in Iranian population is <5%. Furthermore, there is no report of detection of R176X and R243Q in Isfahan and Azeri Turkish populations. These findings confirm the common Mediterranean mutations in this local population, although with more or lower frequencies than those reported in other related studies in Iran. Therefore, it may be necessary to study the PAH gene mutations in other provinces of Iran separately.
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Affiliation(s)
- Keyvan Moradi
- Department of Genetics, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
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Baturina OA, Bondar AA, Tupikin AE, Zhabin SG, Morozov IV. Analysis of phenylalanine hydroxylase gene mutations in phenylketonuria patients from Kemerovo oblast and the Sakha Republic. CYTOL GENET+ 2012. [DOI: 10.3103/s0095452712040032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Georgiou T, Ho G, Vogazianos M, Dionysiou M, Nicolaou A, Chappa G, Nicolaides P, Stylianidou G, Christodoulou J, Drousiotou A. The spectrum of mutations identified in Cypriot patients with phenylalanine hydroxylase deficiency detected through neonatal screening. Clin Biochem 2012; 45:588-92. [PMID: 22330942 DOI: 10.1016/j.clinbiochem.2012.01.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2011] [Revised: 01/17/2012] [Accepted: 01/27/2012] [Indexed: 11/26/2022]
Abstract
OBJECTIVES The purpose of this study was to identify the mutations responsible for phenylalanine hydroxylase deficiency in Cypriot patients detected through neonatal screening. DESIGN AND METHODS Analysis of the PAH gene was performed by direct sequencing of the patients' genomic DNA, MLPA analysis and real-time PCR. RESULTS Among 22 independent alleles thirteen previously described mutations were detected (detection rate 100%), all in compound heterozygosity: p.Arg395Gly (18.2%), c.168+5G>C (13.6%), p.EX3del (9%), c.1066-11G>A (9%), p.Ala403Val (9%), p.Glu178Gly (9%), p.Ser70Pro (4.5%), p.Arg241His (4.5%), p.Phe55fs (4.5%), p.Arg158Gln (4.5%), p.Asp222Gly (4.5%), p.Ala300Ser (4.5%), p.Pro225Thr (4.5%). Of the ten different genotypes, three have been previously reported to be associated with a mild clinical phenotype and to respond to tetrahydrobiopterin (BH₄) administration. CONCLUSIONS Marked genetic heterogeneity was found in Cypriot patients with hyperphenylalaninemia with two mutations accounting for 32% of the alleles. Most of the mutations detected have been found in other European and Mediterranean populations.
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Affiliation(s)
- Theodoros Georgiou
- Department of Biochemical Genetics, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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14
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Rivera I, Mendes D, Afonso Â, Barroso M, Ramos R, Janeiro P, Oliveira A, Gaspar A, Tavares de Almeida I. Phenylalanine hydroxylase deficiency: molecular epidemiology and predictable BH4-responsiveness in South Portugal PKU patients. Mol Genet Metab 2011; 104 Suppl:S86-92. [PMID: 21871829 DOI: 10.1016/j.ymgme.2011.07.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 07/27/2011] [Accepted: 07/28/2011] [Indexed: 11/23/2022]
Abstract
Hyperphenylalaninemia (HPA, OMIM #261600), which includes phenylketonuria (PKU), is caused by mutations in the gene encoding phenylalanine hydroxylase (PAH), being already described more than 600 different mutations. Genotype-phenotype correlation is a useful tool to predict the metabolic phenotype, to establish the better tailored diet and, more recently, to assess the potential responsiveness to BH(4) therapy, a current theme on PKU field. The aim of this study was the molecular analysis of the PAH gene, evaluation of genotype-phenotype relationships and prediction of BH(4)-responsiveness in the HPA population living in South Portugal. We performed the molecular characterization of 83 HPA patients using genomic DNA extracted from peripheral blood samples or Guthrie cards. PAH mutations were scanned by PCR amplification of exons and related intronic boundaries, followed by direct sequence analysis. Intragenic polymorphisms were determined by PCR-RFLP analysis. The results allowed the full characterization of 67 patients. The mutational spectrum encompasses 34 distinct mutations, being the most frequent IVS10nt-11G>A (14.6%), V388M (10.8%), R261Q (8.2%) and R270K (7.6%), which account for 46% of all mutant alleles. Moreover, 12 different haplotypes were identified and most mutations were associated with a single one. Notably, more than half of the 34 mutations belong to the group of more than 70 mutations already identified in BH(4)-responsive patients, according to BIOPKU database. Fifty one different genotypic combinations were found, most of them in single patients and involving a BH(4)-responsive mutation. In conclusion, a significant number (30-35%) of South Portugal PKU patients may potentially benefit from BH(4) therapy which, combined with a less strict diet, or eventually in special cases as monotherapy, may contribute to reduce nutritional deficiencies and minimize neurological and psychological dysfunctions.
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Affiliation(s)
- Isabel Rivera
- Metabolism and Genetics Group, Faculty of Pharmacy, iMed.UL-Research Institute for Medicines and Pharmaceutical Sciences,University of Lisbon, Portugal.
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15
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Richard E, Jorge-Finnigan A, Garcia-Villoria J, Merinero B, Desviat LR, Gort L, Briones P, Leal F, Pérez-Cerdá C, Ribes A, Ugarte M, Pérez B. Genetic and cellular studies of oxidative stress in methylmalonic aciduria (MMA) cobalamin deficiency type C (cblC) with homocystinuria (MMACHC). Hum Mutat 2010; 30:1558-66. [PMID: 19760748 DOI: 10.1002/humu.21107] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Methylmalonic aciduria (MMA) cobalamin deficiency type C (cblC) with homocystinuria (MMACHC) is the most frequent genetic disorder of vitamin B(12) metabolism. The aim of this work was to identify the mutational spectrum in a cohort of cblC-affected patients and the analysis of the cellular oxidative stress and apoptosis processes, in the presence or absence of vitamin B(12). The mutational spectrum includes nine previously described mutations: c.3G>A (p.M1L), c.217C>T (p.R73X), c.271dupA (p.R91KfsX14), c.331C>T (p.R111X), c.394C>T (p.R132X), c.457C>T (p.R153X), c.481C>T (p.R161X), c.565C>A (p.R189S), and c.615C>G (p.Y205X), and two novel changes, c.90G>A (p.W30X) and c.81+2T>G (IVS1+2T>G). The most frequent change was the known c.271dupA mutation, which accounts for 85% of the mutant alleles characterized in this cohort of patients. Owing to its high frequency, a real-time PCR and subsequent high-resolution melting (HRM) analysis for this mutation has been established for diagnostic purposes. All cell lines studied presented a significant increase of intracellular reactive oxygen species (ROS) content, and also a high rate of apoptosis, suggesting that elevated ROS levels might induce apoptosis in cblC patients. In addition, ROS levels decreased in hydroxocobalamin-incubated cells, indicating that cobalamin might either directly or indirectly act as a scavenger of ROS. ROS production might be considered as a phenotypic modifier in cblC patients, and cobalamin supplementation or additional antioxidant drugs might suppress apoptosis and prevent cellular damage in these patients.
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Affiliation(s)
- Eva Richard
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular-Severo Ochoa (SO) Universidad Autónoma de Madrid (UAM)-Consejo Superior de Investigaciones Científicas (CSIC), Universidad Autónoma de Madrid, Campus de Cantoblanco, Madrid, Spain
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16
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Santos LL, Castro-Magalhães M, Fonseca CG, Starling ALP, Januário JN, Aguiar MJB, Carvalho MRS. PKU in Minas Gerais State, Brazil: mutation analysis. Ann Hum Genet 2008; 72:774-9. [PMID: 18798839 DOI: 10.1111/j.1469-1809.2008.00476.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This work was undertaken in order to ascertain the PKU mutational spectrum in Minas Gerais, Brazil, the relative frequency of the mutations in the State and the origin of these mutations by haplotype determination. Minas Gerais is a trihybrid population formed by miscegenation from Europeans, Africans and Amerindians. All 13 exons of the PAH gene from 78 PKU patients were analyzed, including splicing sites and the promoter region. We identified 30 different mutations and 98% of the PAH alleles were established. A new mutation (Q267X) was identified as well. The most common mutations found were V388M (21.2), R261Q (16.0%), IVS10-11G>A (15.3%), I65T (5.8%), IVS2+5G>C (5.8%), R252W (5.1%), IVS2+5G>A (4.5%), P281L (3.8%) and L348V (3.2%). These nine mutations correspond to 80% of the PKU alleles in the state. Haplotypes were determined to characterize the origin of the PAH alleles. The majority of the mutations found, with respective haplotypes, are frequent in the Iberian Peninsula. However, there were some mutations that are rare in Europe and four previously unreported mutation-haplotype associations. I65T and Q267X were found in association with haplotype 38 and may be African in origin or the result of miscegenation in the Brazilian population.
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Affiliation(s)
- L L Santos
- Departamento de Biologia, Universidade Federal de Minas Gerais-Instituto de Ciências Biológicas, Belo Horizonte, MG, Brazil
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17
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Steiner CE, Acosta AX, Guerreiro MM, Marques-de-Faria AP. Genotype and natural history in unrelated individuals with phenylketonuria and autistic behavior. ARQUIVOS DE NEURO-PSIQUIATRIA 2008; 65:202-5. [PMID: 17607414 DOI: 10.1590/s0004-282x2007000200003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Accepted: 12/05/2006] [Indexed: 11/22/2022]
Abstract
We describe three unrelated individuals, two males (ages 35 and 9) and a female (age 8) presenting with late diagnosed phenylketonuria (PKU) and autistic behavior, all showing poor adhesion to the dietary treatment resulting in high plasmatic phenylalanine levels, particularly in the oldest subject. Clinical findings included hair hypopigmentation, microcephaly, severe mental retardation with absent development of verbal language and autistic symptoms in all three patients, whereas variable neurological signs such as seizures, spasticity, ataxia, aggressivity, and hyperactivity were individually found. Homozygosity for the IVS10nt11g/a (IVS10nt546) was found in all. This is the first report of molecular findings in subjects with PKU also presenting with autistic features. The authors discuss if this mutation is particularly involved in the association of autistic symptoms in untreated PKU individuals.
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Affiliation(s)
- Carlos Eduardo Steiner
- Departamento de Genética Médica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil.
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18
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Lüleyap HU, Alptekin D, Pazarbaşi A, Kasap M, Kasap H, Demirhindi H, Mungan N, Ozer G, Froster UG. The importance of arginine mutation for the evolutionary structure and function of phenylalanine hydroxylase gene. Mutat Res 2006; 601:39-45. [PMID: 16765994 DOI: 10.1016/j.mrfmmm.2006.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2006] [Revised: 04/21/2006] [Accepted: 05/08/2006] [Indexed: 05/10/2023]
Abstract
Phenylalanine hydroxylase (PAH) gene mutations were investigated in 23 (46 alleles) unrelated phenylketonuria (PKU) patients in Cukurova region. First, all exons of PAH gene were screened by denaturing high performance liquid chromatography (DHPLC), and then, the suspicious samples were analyzed by direct sequencing technique. Consequently, the following results were obtained: IVS10-11g-->a splicing mutation in 27/46 (58.7%), R261Q mutation in 7/46 (15.2%) and E178G, R243X, R243Q, P281L, Y386C, R408W mutations, each found in the frequency of 2/46 (4.3%). In many countries, Arginine mutations have the highest frequency among PAH gene mutations in PKU patients. Although, CpG dinucleotids are effective in mutations resulting in arginine changes, this finding originated from the studies on the causes of mutations rather than the studies on the importance of arginine amino acid. In our analyses, we have detected that a majority of mutations causing a change in arginine and other amino acids concentrated in exon 7 comprising the catalytic domain (residues 143-410) of PAH gene. Several studies has emphasized the role of arginine amino acid; with the following outcomes; arginine repetition is significant for RNA binding proteins, and for histon proteins in eukaryotic gene expression, and also arginine repetition occurring in the structure of signal recognition particle's (SRPs) as a consequence of post-translational processes is very important in terms of gene expression. Therefore, the role of arginine amino acid in PAH gene is rather remarkable in that it shows the role of amino acids in the protein/RNA interaction that has started in the evolutionary process and is still preserved and maintained in the motif formation of active domain structure due to its strong binding properties. Thus, such properties imply that both arginine amino acid and exon 7 is of great significance with regards to the structure and function of the PheOH enzyme.
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Affiliation(s)
- H Umit Lüleyap
- University of Cukurova, Faculty of Medicine, Department of Medical Biology and Genetics, Adana, Turkey.
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19
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Santana da Silva LC, Carvalho TS, da Silva FB, Morari L, Fachel AA, Pires R, Refosco LF, Desnick RJ, Giugliani R, Saraiva Pereira ML. Molecular characterization of phenylketonuria in South Brazil. Mol Genet Metab 2003; 79:17-24. [PMID: 12765842 DOI: 10.1016/s1096-7192(03)00032-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Phenylketonuria (PKU) is an autosomal recessive disorder due to phenylalanine hydroxylase (PAH) deficiency. The PAH gene, located at 12q22-q24.1, includes about 90kb and contains 13 exons. To date, more than 420 different alterations have been identified in the PAH gene. To determine the nature and frequency of PAH mutations in PKU patients from South Brazil, mutation analysis was performed on genomic DNA from 23 unrelated PKU patients. The 13 exons and flanking regions of the PAH gene were amplified by PCR and the amplicons were analyzed by single strand conformation polymorphism (SSCP). Amplicons that showed abnormal migration patterns were analyzed by restriction endonuclease digestion and/or sequencing. Twenty-two previously reported mutations were identified including R261X, R408W, IVS2nt5g-->c, R261Q, and V388M. Polymorphisms were observed in 48.8% of the PKU patients, the most frequent being IVS2nt19t-->c, V245V, and IVS12nt-35c-->t. In addition, two novel sequence variants were identified: 1378g-->t in the 3(')-untranslated region in exon 13 which may be disease-causing and an intron 12 polymorphism, IVS12nt-15t-->c. The mutation spectrum in the patients from Southern Brazil differed from that observed in patients from other Latin American countries and further defined the molecular heterogeneity of this disease.
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20
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Abstract
Phenylketonuria (PKU) is heterogeneous. More than 400 different mutations in the phenylalanine hydroxylase (PAH) gene have been identified. In a systematic review of the molecular genetics of PKU in Europe we identified 29 mutations that may be regarded as prevalent in European populations. Comprehensive regional data for these mutations were collated from all available studies. The spectrum of mutations found in individual regions results from a combination of factors including founder effect, range expansion and migration, genetic drift, and probably heterozygote advantage. Common mutations include R408W on a haplotype 2 background in Eastern Europe, IVS10-11G>A in the Mediterranean, IVS12+1G>A in Denmark and England, Y414C in Scandinavia, I65T in Western Europe, and R408W on haplotype 1 in the British Isles. Molecular data from mild hyperphenylalaninemia (MHP) patients are available from a number of countries, but it is currently not possible to calculate relative allele frequencies. The available data on PAH mutations are useful for the understanding of both the clinical features and the population genetics of PAH deficiency in Europe.
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Affiliation(s)
- Johannes Zschocke
- Institut für Humangenetik, Ruprecht-Karls-Universität, Heidelberg, Germany.
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21
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Acosta A, Silva W, Carvalho T, Gomes M, Zago M. Mutations of the phenylalanine hydroxylase (PAH) gene in Brazilian patients with phenylketonuria. Hum Mutat 2001; 17:122-30. [PMID: 11180595 DOI: 10.1002/1098-1004(200102)17:2<122::aid-humu4>3.0.co;2-c] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In the present study, 115 Brazilian families with phenylketonuria (PKU), mainly from the Southeast of the country, were studied using three laboratory methods (DGGE, SSCP, and sequencing). All 13 exons of the PAH gene were analyzed, including the splicing sites and the promoter region. We identified 50 distinct mutations and characterized 91% of the mutant alleles. The five most prevalent mutations of the 50 mutations identified (50% of the PKU alleles) were IVS10nt-11G-->A (17.4%), followed by R261Q (12.2%), V388M (9.1%), R252W (6.5%), and R270K (4.8%). The other mutations were rare. The mutation spectrum included 10 novel mutations (IVS5nt-54A-->G, IVS6nt17G-->T, E205A, F240S, K274E, I318T, L321L, C357G, IVS11nt17G-->A, and S411X). To characterize the origin and distribution of the PAH alleles we determined the association between the detected mutations and the PCR/RFLP haplotypes and VNTR alleles located on the PAH gene. For those patients whose mutant alleles were detected, we calculated the correlation with pretreatment phenylalanine levels, thus establishing a genotype/phenotype correlation. The present results confirm the marked heterogeneity observed at the PAH locus and contribute to the understanding of the distribution and frequency of PKU mutations in the Brazilian population.
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Affiliation(s)
- A Acosta
- Faculty of Medicine of Ribeirão Preto and Fundação Hemocentro de Ribeirão Preto, São Paulo, Brazil.
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22
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Rivera I, Cabral A, Almeida M, Leandro P, Carmona C, Eusébio F, Tasso T, Vilarinho L, Martins E, Lechner MC, de Almeida IT, Konecki DS, Lichter-Konecki U. The correlation of genotype and phenotype in Portuguese hyperphenylalaninemic patients. Mol Genet Metab 2000; 69:195-203. [PMID: 10767174 DOI: 10.1006/mgme.2000.2971] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To understand the basis for the clinical heterogeneity of phenylalanine hydroxylase deficiency among Portuguese hyperphenylalaninemic patients, genotype-phenotype correlations were established. A group of 61 patients was completely genotyped, leading to the identification of 20 different mutant alleles in 36 different genotypic combinations, including a mutant allele not reported previously. The severity of those mutations found within this hyperphenylalaninemic population, which have not been previously expressed in vitro, were assessed. The results obtained by the present study exhibit a strong correlation between the predicted residual enzyme activity, as deduced from the genotype of the patients, and the biochemical phenotype represented by the diagnostic parameters (phenylalanine levels before the beginning of treatment and the dietary phenylalanine tolerance). It was observed that only a judicious follow-up and compliance with the appropriate diet permits the correct assessment of the clinical phenotype of the patients. Additionally, based upon the correlation observed between genotypes and diagnostic parameters, it was possible to predict the potential residual enzyme activity of those mutations (identified in our patients) which have not yet been studied in vitro.
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Affiliation(s)
- I Rivera
- Centro de Patogénese Molecular, Faculdade de Farmácia, University of Lisboa, Avenida das Forças Armadas, Lisboa, 1600, Portugal
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23
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Leandro P, Rivera I, Lechner MC, de Almeida IT, Konecki D. The V388M mutation results in a kinetic variant form of phenylalanine hydroxylase. Mol Genet Metab 2000; 69:204-12. [PMID: 10767175 DOI: 10.1006/mgme.2000.2970] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The molecular mechanism underlying the metabolic defect in phenylketonuria (PKU) patients carrying the V388M missense mutation of the phenylalanine hydroxylase (PAH) gene has been characterized. An in vitro prokaryotic expression system has been used to produce both the wild-type and the mutant form of the human PAH (hPAH) protein. The recombinant enzymes, obtained as fusion proteins, were purified by immobilized metal affinity chromatography and recovered in high yields. The wild-type hPAH possessed a high specific activity and its kinetic properties were the same as those reported for the enzyme isolated from human liver and other recombinant wild-type hPAH enzymes. The recombinant V388M mutant form exhibited a reduced specific activity equivalent to 30% of the wild-type hPAH enzyme when assayed using the synthetic cofactor (6-methyltetrahydropterin). Lower values were obtained (23 and 19%) when the mutant enzyme was assayed with the natural cofactor ((6R)-tetrahydrobiopterin) and different concentrations of l-phenylalanine. The enzyme kinetic studies of the V388M mutant protein revealed that this enzyme was a kinetic variant form of hPAH with a reduced affinity for l-phenylalanine and for the natural cofactor ((6R)-tetrahydrobiopterin). The residual activities determined for the V388M form of hPAH were compatible with the phenotype presented by the PKU patients harboring the V388M mutation in the PAH gene.
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Affiliation(s)
- P Leandro
- Centro de Patogénese Molecular, Faculdade de Farmácia, University of Lisboa, Lisboa, 1600, Portugal
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Cole FS, Hamvas A, Rubinstein P, King E, Trusgnich M, Nogee LM, deMello DE, Colten HR. Population-based estimates of surfactant protein B deficiency. Pediatrics 2000; 105:538-41. [PMID: 10699106 DOI: 10.1542/peds.105.3.538] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE Surfactant protein B deficiency is a lethal cause of respiratory distress in infancy that results most commonly from a homozygous frameshift mutation (121ins2). Using independent clinical ascertainment and molecular methods in different populations, we sought to determine allele frequency. STUDY DESIGN Using clinical characteristics of the phenotype of affected infants, we screened the Missouri linked birth-death database (n = 1 052 544) to ascertain potentially affected infants. We used molecular amplification and restriction enzyme digestion of DNA samples from a metropolitan New York birth cohort (n = 6599) to estimate allele frequency. RESULTS The point estimate and 95% confidence interval of the 121ins2 allele frequency in the Missouri cohort are 1/1000 individuals (.03-5.6/1000) and in the New York cohort are.15/1000 (. 08-.25/1000). These estimates are not statistically different. CONCLUSIONS The close approximation of these independent estimates suggests accurate gene frequency (approximately one 121ins2 mutation per 1000-3000 individuals) despite its rare occurrence and that this mutation does not account for the majority of full-term infants with lethal respiratory distress.
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Affiliation(s)
- F S Cole
- Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine and St Louis Children's Hospital, St Louis, MO 63110, USA.
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