1
|
Whittaker MN, Brooks DL, Quigley A, Jindal I, Said H, Qu P, Wang JZ, Ahrens-Nicklas RC, Musunuru K, Alameh MG, Peranteau WH, Wang X. Improved specificity and efficacy of base-editing therapies with hybrid guide RNAs. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.22.590531. [PMID: 38712058 PMCID: PMC11071363 DOI: 10.1101/2024.04.22.590531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Phenylketonuria (PKU), hereditary tyrosinemia type 1 (HT1), and mucopolysaccharidosis type 1 (MPSI) are autosomal recessive disorders linked to the phenylalanine hydroxylase (PAH) gene, fumarylacetoacetate hydrolase (FAH) gene, and alpha-L-iduronidase (IDUA) gene, respectively. Potential therapeutic strategies to ameliorate disease include corrective editing of pathogenic variants in the PAH and IDUA genes and, as a variant-agnostic approach, inactivation of the 4-hydroxyphenylpyruvate dioxygenase (HPD) gene, a modifier of HT1, via adenine base editing. Here we evaluated the off-target editing profiles of therapeutic lead guide RNAs (gRNAs) that, when combined with adenine base editors correct the recurrent PAH P281L variant, PAH R408W variant, or IDUA W402X variant or disrupt the HPD gene in human hepatocytes. To mitigate off-target mutagenesis, we systematically screened hybrid gRNAs with DNA nucleotide substitutions. Comprehensive and variant-aware specificity profiling of these hybrid gRNAs reveal dramatically reduced off-target editing and reduced bystander editing. Lastly, in a humanized PAH P281L mouse model, we showed that when formulated in lipid nanoparticles (LNPs) with adenine base editor mRNA, selected hybrid gRNAs revert the PKU phenotype, substantially enhance on-target editing, and reduce bystander editing in vivo. These studies highlight the utility of hybrid gRNAs to improve the safety and efficacy of base-editing therapies.
Collapse
Affiliation(s)
- Madelynn N. Whittaker
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Dominique L. Brooks
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Aidan Quigley
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ishaan Jindal
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Hooda Said
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Department of Bioengineering, George Mason University, Fairfax, Virginia, USA
| | - Ping Qu
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Rebecca C. Ahrens-Nicklas
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Human Genetics and Metabolism, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
| | - Kiran Musunuru
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- These authors jointly directed this work: Kiran Musunuru, Mohamad-Gabriel Alameh, William H. Peranteau, and Xiao Wang
| | - Mohamad-Gabriel Alameh
- Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Department of Bioengineering, George Mason University, Fairfax, Virginia, USA
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- These authors jointly directed this work: Kiran Musunuru, Mohamad-Gabriel Alameh, William H. Peranteau, and Xiao Wang
| | - William H. Peranteau
- The Center for Fetal Research, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- Division of Pediatric General, Thoracic, and Fetal Surgery, Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania, USA
- These authors jointly directed this work: Kiran Musunuru, Mohamad-Gabriel Alameh, William H. Peranteau, and Xiao Wang
| | - Xiao Wang
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
- These authors jointly directed this work: Kiran Musunuru, Mohamad-Gabriel Alameh, William H. Peranteau, and Xiao Wang
| |
Collapse
|
2
|
Brooks DL, Whittaker MN, Said H, Dwivedi G, Qu P, Musunuru K, Ahrens-Nicklas RC, Alameh MG, Wang X. A base editing strategy using mRNA-LNPs for in vivo correction of the most frequent phenylketonuria variant. HGG ADVANCES 2024; 5:100253. [PMID: 37922902 PMCID: PMC10800763 DOI: 10.1016/j.xhgg.2023.100253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/19/2023] [Accepted: 10/19/2023] [Indexed: 11/07/2023] Open
Abstract
The c.1222C>T (p.Arg408Trp) phenylalanine hydroxylase (PAH) variant is the most frequent cause of phenylketonuria (PKU), an autosomal recessive disorder characterized by accumulation of blood phenylalanine (Phe) to neurotoxic levels. Here we devised a therapeutic base editing strategy to correct the variant, using prime-edited hepatocyte cell lines engineered with the c.1222C>T variant to screen a variety of adenine base editors and guide RNAs in vitro, followed by assessment in c.1222C>T humanized mice in vivo. We found that upon delivery of a selected adenine base editor mRNA/guide RNA combination into mice via lipid nanoparticles (LNPs), there was sufficient PAH editing in the liver to fully normalize blood Phe levels within 48 h. This work establishes the viability of a base editing strategy to correct the most common pathogenic variant found in individuals with the most common inborn error of metabolism, albeit with potential limitations compared with other genome editing approaches.
Collapse
Affiliation(s)
- Dominique L Brooks
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Madelynn N Whittaker
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Hooda Said
- Department of Bioengineering, George Mason University, Fairfax, VA 22030, USA
| | - Garima Dwivedi
- Division of Infectious Diseases, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ping Qu
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kiran Musunuru
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Rebecca C Ahrens-Nicklas
- Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Metabolic Disease Program, Division of Human Genetics, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Mohamad-Gabriel Alameh
- Department of Bioengineering, George Mason University, Fairfax, VA 22030, USA; Department of Pathology and Laboratory Medicine, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Pathology and Laboratory Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Xiao Wang
- Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Ajami N, Soleimani A, Jafarzadeh‐Esfehani R, Hasanpour M, Rashid Shomali R, Abbaszadegan MR. Mutational landscape of phenylketonuria in Iran. J Cell Mol Med 2023; 27:2457-2466. [PMID: 37525467 PMCID: PMC10468661 DOI: 10.1111/jcmm.17865] [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: 07/27/2022] [Revised: 06/11/2023] [Accepted: 06/28/2023] [Indexed: 08/02/2023] Open
Abstract
To date more than 1000 different variants in the PAH gene have been identified in patients with phenylketonuria (PKU). In Iran, several studies have been performed to investigate the genetics bases of the PKU in different parts of the country. In this study, we have analysed and present an update of the mutational landscape of the PAH gene as well as the population genetics and frequencies of detected variants for each cohort. Published articles on PKU mutations in Iran were identified through a comprehensive PubMed, Google Scholar, Web of Science (ISI), SCOPUS, Elsevier, Wiley Online Library and SID literature search using the terms: "phenylketonuria", "hyperphenylalaninemia", and "PKU" in combination with "Iran", "Iranian population", "mutation analysis", and "Molecular genetics". Among the literature-related to genetics of PKU, 18 studies were on the PKU mutations. According to these studies, in different populations of Iran 1497 patients were included for mutation detection that resulted in detection of 129 different mutations. Results of genetic analysis of the different cohorts of Iranian PKU patients show that the most prevalent mutation in Iran is the pathogenic splice variant c.1066-11G > A, occurring in 19.54% of alleles in the cohort. Four other common mutations were p.Arg261Gln, p.Pro281Leu, c.168 + 5G > C and p.Arg243Ter (8.18%, 6.45%, 5.88% and 3.7%, respectively). One notable feature of the studied populations is its high rate of consanguineous marriages. Considering this feature, determining the prevalent PKU mutations could be advantageous for designing screening and diagnostic panels in Iran.
Collapse
Affiliation(s)
- Naser Ajami
- Department of Medical Genetics and Molecular Medicine, School of MedicineMashhad University of Medical SciencesMashhadIran
- Medical Genetics Research Center, School of MedicineMashhad University of Medical SciencesMashhadIran
| | - Anvar Soleimani
- Department of Medical Microbiology, College of Health SciencesCihan University‐ SulaimaniyaSulaimaniyaIraq
| | - Reza Jafarzadeh‐Esfehani
- Blood Borne Infections Research Center, Academic Center for EducationCulture and Research (ACECR)‐ Khorasan RazaviMashhadIran
| | - Mojtaba Hasanpour
- Department of Biology, Faculty of SciencesUniversity of GuilanRashtIran
| | - Romina Rashid Shomali
- Reproductive Health Research Center, Department of Obstetrics and Gynecology, Alzahra HospitalGuilan University of Medical SciencesRashtIran
| | - Mohammad Reza Abbaszadegan
- Department of Medical Genetics and Molecular Medicine, School of MedicineMashhad University of Medical SciencesMashhadIran
- Immunology Research CenterMashhad University of Medical SciencesMashhadIran
| |
Collapse
|
5
|
Alibakhshi R, Mohammadi A, Salari N, Khamooshian S, Kazeminia M, Moradi K. Spectrum of PAH gene mutations in 1547 phenylketonuria patients from Iran: a comprehensive systematic review. Metab Brain Dis 2021; 36:767-780. [PMID: 33625639 DOI: 10.1007/s11011-021-00698-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 02/16/2021] [Indexed: 12/12/2022]
Abstract
As one of the highest prevalence rates in the world, the prevalence of Phenylketonuria (PKU) in Iran has been estimated at 16.5 per 100,000 neonates. The objective of this study was to evaluate the spectrum and frequency of mutations of the phenylalanine hydroxylase (PAH) gene in Iranian PKU patients. A systematic review was carried out on previous studies on PAH gene mutations in Iranian PKU patients. A complete search was carried out on the on-line databases of Scopus, Web of Science, PubMed/Medline, ProQuest, Science Direct, Magiran, SID and the search engine Google Scholar. The keywords of Phenylketonuria, PKU, Phenylalanine Hydroxylase, PAH, and Iran, as well as their Persian equivalents, in all possible combinations were used. Finally, a total of 21 eligible articles with a sample size of 1547 Iranian PKU patients, published between 2003 and 2020, were included in our systematic review. A total of 129 different PAH gene mutations including, IVS10-11G > A (c.1066-11G > A) (19.23%), p.R261Q (c.782G > A) (7.63%), p.P281L (c.842C > T) (6.24%), IVS2 + 5G > C (c.168 + 5G > C) (5.75%), p.R243* (c.727C > T) (3.59%), IVS9 + 5G > A (c.969 + 5G > A) (2.84%), p.R176* (c.526C > T) (2.42%), p.Lys363Nfs*37 (c.1089delG) (2.13%), IVS11 + 1G > C (c.1199 + 1G > C) (2.07%) and p.L48S (c.143 T > C) (2.04%) were identified. The spectrum and frequency of mutations observed in Iran were closer to those observed in the Mediterranean countries. Our results are valuable in planning panel-based studies in provinces with incomplete data on PAH gene mutations. This study is a good reference for genetic counselors and physicians who advise couples in making decisions to maintain or terminate a pregnancy.
Collapse
Affiliation(s)
- Reza Alibakhshi
- Department of Biochemistry, School of Medicine, Kermanshah University of Medical Sciences, Parastar Street, Kermanshah, Kermanshah Province, Iran
| | - Aboozar Mohammadi
- Student Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Nader Salari
- Department of Biostatistics, School of Health, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Sahand Khamooshian
- Student Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Mohsen Kazeminia
- Student Research Committee, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Keivan Moradi
- Department of Biochemistry, School of Medicine, Kermanshah University of Medical Sciences, Parastar Street, Kermanshah, Kermanshah Province, Iran.
| |
Collapse
|
6
|
Abstract
Phenylketonuria (PKU; also known as phenylalanine hydroxylase (PAH) deficiency) is an autosomal recessive disorder of phenylalanine metabolism, in which especially high phenylalanine concentrations cause brain dysfunction. If untreated, this brain dysfunction results in severe intellectual disability, epilepsy and behavioural problems. The prevalence varies worldwide, with an average of about 1:10,000 newborns. Early diagnosis is based on newborn screening, and if treatment is started early and continued, intelligence is within normal limits with, on average, some suboptimal neurocognitive function. Dietary restriction of phenylalanine has been the mainstay of treatment for over 60 years and has been highly successful, although outcomes are still suboptimal and patients can find the treatment difficult to adhere to. Pharmacological treatments are available, such as tetrahydrobiopterin, which is effective in only a minority of patients (usually those with milder PKU), and pegylated phenylalanine ammonia lyase, which requires daily subcutaneous injections and causes adverse immune responses. Given the drawbacks of these approaches, other treatments are in development, such as mRNA and gene therapy. Even though PAH deficiency is the most common defect of amino acid metabolism in humans, brain dysfunction in individuals with PKU is still not well understood and further research is needed to facilitate development of pathophysiology-driven treatments.
Collapse
Affiliation(s)
- Francjan J van Spronsen
- Beatrix Children's Hospital, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands.
| | - Nenad Blau
- University Children's Hospital in Zurich, Zurich, Switzerland
| | - Cary Harding
- Department of Molecular and Medical Genetics and Department of Pediatrics, Oregon Health & Science University, Oregon, USA
| | | | - Nicola Longo
- Department of Pediatrics, University of Utah, Salt Lake City, Utah, USA
| | - Annet M Bosch
- University of Amsterdam, Department of Pediatrics, Division of Metabolic Disorders, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| |
Collapse
|
7
|
Molecular characterization of Thai patients with phenylalanine hydroxylase deficiency and in vitro functional study of two novel PAH variants. Mol Biol Rep 2021; 48:2063-2070. [PMID: 33677757 DOI: 10.1007/s11033-021-06163-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 01/15/2021] [Indexed: 10/22/2022]
Abstract
Phenylketonuria (PKU) is an autosomal recessive amino acid metabolism disorder caused by variants in the gene encoding phenylalanine hydroxylase (PAH; EC1.14.16.1). This study aimed to assess the specific heterogeneity of PAH variants found in Thai population as well as evaluate enzyme activity and expression of novel variants. PAH gene from 13 patients was analyzed by PCR amplification and direct Sanger-sequencing of 13 exons of the coding region. The novel variants were transiently transfected in COS-7 cells for functional verification. Eleven different PAH variants were identified: all pathogenic variants were missense variants, of which the most frequent variant was p.R169L, accounting for 24% (6/25) of all identified alleles. Two novel variants p.R169L and p.Y317N and previously reported variants with mutated residues at the same positions (p.R169H and p.Y317H) were expressed in COS-7 cells. These showed mildly impaired residual activity levels (42.3-63.1% of wild type), while the protein levels were well expressed (82.8-110%), except for p.R169L, which showed decreased protein expression of 55.7% compared to the wild type enzyme. All subjects with p.R169L identified in at least one of pathogenic alleles (one case is homozygous) had a metabolic phenotype of mild hyperphenylalaninemia (HPA). Our data has expanded the information on the genetic heterogeneity of Thai patients with PAH deficiency. This finding emphasizes the importance of genotyping in patients with HPA, and in vitro studies can provide additional information for prediction of phenotype.
Collapse
|
8
|
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.
Collapse
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
| |
Collapse
|
9
|
Darbà J. Characteristics, comorbidities, and use of healthcare resources of patients with phenylketonuria: a population-based study. J Med Econ 2019; 22:1025-1029. [PMID: 31237171 DOI: 10.1080/13696998.2019.1636381] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Background: Phenylketonuria is a well-known disease, yet the characteristics of the affected population and their use of healthcare resources have not been comprehensively evaluated. Patient characteristics and use of resources are subjects of interest for most governments, especially for a disease included in newborn screening programs. Objective: The aim of this study was to determine characteristics and use of healthcare resources of patients with phenylketonuria in the region of Catalonia. Methods: Records of 289 patients admitted with phenylketonuria between 2007 and 2017 were extracted from the PADRIS database that includes admission data from primary care centers, hospitals (inpatient and outpatient care), extended care facilities, and mental health centers. Results: The patient population was composed of 140 male patients and 149 female patients, and 102 patients were registered via newborn screening during the study period. Patients were admitted on average 2.19 times per year, mostly into primary care centers which concentrated the largest portion of direct medical expenses. Similar percentages of urgent and scheduled admissions were registered both in primary care and hospitals. Annual direct medical cost of treating patients with phenylketonuria was €667 per patient. Finally, 66.80% of the patients suffered from chronic conditions affecting two or more systems, likely to correspond to a wide variety of conditions. Conclusions: Altogether, phenylketonuria patient demographics and direct medical costs in Catalonia have been revised. Patients diagnosed with phenylketonuria appeared 1.3-times more likely to suffer from chronic conditions in distinct organ systems, which is expected to have an effect on their use of healthcare resources. These results support the need to adapt and improve the healthcare system, taking multimorbidity into consideration in an effort to control the medical expenses derived.
Collapse
Affiliation(s)
- Josep Darbà
- Universitat de Barcelona , Barcelona , Spain
| |
Collapse
|
10
|
Enacán RE, Miñana MN, Fernandez L, Valle MG, Salerno M, Fraga CI, Santos-Simarro F, Prieto L, Lapunzina P, Specola N, Chiesa AE. Phenylalanine Hydroxylase (PAH) Genotyping in PKU Argentine Patients. JOURNAL OF INBORN ERRORS OF METABOLISM AND SCREENING 2019. [DOI: 10.1590/2326-4594-jiems-2019-0012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Affiliation(s)
| | | | | | | | | | | | | | - Laura Prieto
- Fundación de Endocrinología Infantil (FEI), Argentina
| | | | | | | |
Collapse
|
11
|
Esfahani MS, Vallian S. A comprehensive study of phenylalanine hydroxylase gene mutations in the Iranian phenylketonuria patients. Eur J Med Genet 2018; 62:103559. [PMID: 30389586 DOI: 10.1016/j.ejmg.2018.10.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/09/2018] [Accepted: 10/24/2018] [Indexed: 11/29/2022]
Abstract
Phenylketonuria (PKU) is a metabolic disorder caused by mutations in the phenylalanine hydroxylase (PAH) gene. After thalassemia, PKU is considered as the most common autosomal recessive diseases in the Iranian population. Therefore, an efficient diagnostic strategy is required to identify disease-causing mutations in this population. Following our first report in 2003, here we presented a comprehensive study on the mutation spectrum of the PAH gene in the Iranian population. This study was performed on 280 unrelated chromosomes from 140 Iranian patients with classic PKU. All 13 exons as well as exon-intron boundaries of the PAH gene were analyzed by direct DNA sequencing. Thirty four different mutations were identified by a mutation detection rate of 100%. IVS10-11G > A, p.P281L, R261Q, p.F39del and IVS11+1G > C were the most prevalent mutations with frequencies of 26.07%, 19.3%, 12.86%, 6.07 and 3.93%, respectively. All other mutations represented a relative frequency less than 3.5%. The data from this study provided a comprehensive spectrum of the PAH gene mutations which can facilitate carrier detection and prenatal diagnosis of PKU disease in the Iranian population.
Collapse
Affiliation(s)
| | - Sadeq Vallian
- Division of Genetics, Department of Biology, Faculty of Science, University of Isfahan, Isfahan, IR, Iran.
| |
Collapse
|
12
|
Himmelreich N, Shen N, Okun JG, Thiel C, Hoffmann GF, Blau N. Relationship between genotype, phenylalanine hydroxylase expression and in vitro activity and metabolic phenotype in phenylketonuria. Mol Genet Metab 2018; 125:86-95. [PMID: 30037505 DOI: 10.1016/j.ymgme.2018.06.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 06/21/2018] [Accepted: 06/22/2018] [Indexed: 01/22/2023]
Abstract
Residual phenylalanine hydroxylase (PAH) activity is the main determinant of the metabolic phenotype in phenylketonuria (PKU). The genotypic heterogeneity of PKU, involving >1000 PAH variants and over 2500 different genotypes, makes genotype-based phenotype prediction challenging. While a relationship between PAH variants and the metabolic phenotype is well established, we questioned the importance of PAH expression and residual in vitro activity for the metabolic phenotype. Thirty-four PAH variants (p.F39 L, p.A47V, p.D59Y, p.I65S, p.R68G, p.R68S, p.E76G, p.A104D, p.D143G, p.R155H, p.R176L, p.V190A, p.G218 V, p.R241C, p.R243Q, p.P244L, p.R252W, p.R261Q, p.E280K, p.R297H, p.A300S, p.I306V, p.A309V, p.L311P, p.A313T, p.L348 V, p.V388 M, A403V, p.R408Q, p.R408W, p.R413P, p.D415N, p.Y417H, and p.A434D) were transiently transfected into COS-7 cells, and expression of PAH was investigated. Expression patterns were compared with in vitro PAH activity and allelic phenotype values (APVs). In vitro PAH activity was significantly higher (p < .01) in variants associated with mild hyperphenylalaninemia (PAH activity = 52.1 ± 8.5%; APV = 6.7-10.0) than that in classic PKU variants (PAH activity = 21.1 ± 7.0%; APV = 0-2.7). Mild PKU variants (PAH activity = 40.2 ± 7.6%; APV = 2.8-6.6) were not significantly different from mild hyperphenylalaninemia, but there was a difference (p < .048) compared with classic PKU phenotypes.
Collapse
Affiliation(s)
- Nastassja Himmelreich
- Center for Child and Adolescent Medicine, and Dietmar-Hopp Metabolic Center, University of Heidelberg, Heidelberg, Germany
| | - Nan Shen
- Center for Child and Adolescent Medicine, and Dietmar-Hopp Metabolic Center, University of Heidelberg, Heidelberg, Germany; Department of Rehabilitation Medicine, Xin Hua Hospital affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jürgen G Okun
- Center for Child and Adolescent Medicine, and Dietmar-Hopp Metabolic Center, University of Heidelberg, Heidelberg, Germany
| | - Christian Thiel
- Center for Child and Adolescent Medicine, and Dietmar-Hopp Metabolic Center, University of Heidelberg, Heidelberg, Germany
| | - Georg F Hoffmann
- Center for Child and Adolescent Medicine, and Dietmar-Hopp Metabolic Center, University of Heidelberg, Heidelberg, Germany
| | - Nenad Blau
- Center for Child and Adolescent Medicine, and Dietmar-Hopp Metabolic Center, University of Heidelberg, Heidelberg, Germany.
| |
Collapse
|
13
|
Garbade SF, Shen N, Himmelreich N, Haas D, Trefz FK, Hoffmann GF, Burgard P, Blau N. Allelic phenotype values: a model for genotype-based phenotype prediction in phenylketonuria. Genet Med 2018; 21:580-590. [DOI: 10.1038/s41436-018-0081-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/31/2018] [Indexed: 02/08/2023] Open
|
14
|
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]
|
15
|
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]
|
16
|
Pàmpols T, Ramos FJ, Lapunzina P, Gozalo‐Salellas I, Pérez‐Jurado LA, Pujol A. A view on clinical genetics and genomics in Spain: of challenges and opportunities. Mol Genet Genomic Med 2016; 4:376-91. [PMID: 27468414 PMCID: PMC4947857 DOI: 10.1002/mgg3.232] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
A view on clinical genetics and genomics in Spain: of challenges and opportunities.
Collapse
Affiliation(s)
- Teresa Pàmpols
- Division of Inborn Errors of MetabolismDepartment of Biochemistry and Molecular GeneticsHospital ClinicBarcelonaSpain
- Center for Biomedical Research on Rare Diseases CIBERER U737BarcelonaSpain
| | - Feliciano J. Ramos
- Unit of Clinical GeneticsService of PediatricsUniversity Hospital “Lozano Blesa”ZaragozaSpain
- Functional GenomicsDepartment PediatricsUniversity of Zaragoza Medical SchoolZaragozaSpain
- Center for Biomedical Research on Rare Diseases CIBERER‐GCV02ZaragozaSpain
| | - Pablo Lapunzina
- Clinical Genetics UnitInstitute of Medical and Molecular Genetics (INGEMM)IdiPAZHospital Universitario La PazMadridSpain
- Center for Biomedical Research on Rare Diseases CIBERER U753MadridSpain
| | - Ignasi Gozalo‐Salellas
- Department of Romance LanguagesUniversity of Pennsylvania521 Williams Hall 255 S. 36th StreetPhiladelphiaPennsylvania19104
| | - Luis A. Pérez‐Jurado
- Genetics UnitDepartment of Experimental and Health SciencesPompeu Fabra University (UPF)BarcelonaSpain
- Hospital del Mar Research Institute (IMIM)BarcelonaSpain
- Center for Biomedical Research on Rare Diseases CIBERER U735BarcelonaSpain
| | - Aurora Pujol
- Neurometabolic Diseases LaboratoryInstitute of NeuropathologyIDIBELLBarcelonaSpain
- Center for Biomedical Research on Rare Diseases CIBERER U759BarcelonaSpain
- Catalan Institution of Research and Advanced Studies (ICREA)BarcelonaSpain
| |
Collapse
|
17
|
Aldámiz-Echevarría L, Llarena M, Bueno MA, Dalmau J, Vitoria I, Fernández-Marmiesse A, Andrade F, Blasco J, Alcalde C, Gil D, García MC, González-Lamuño D, Ruiz M, Ruiz MA, Peña-Quintana L, González D, Sánchez-Valverde F, Desviat LR, Pérez B, Couce ML. Molecular epidemiology, genotype-phenotype correlation and BH4 responsiveness in Spanish patients with phenylketonuria. J Hum Genet 2016; 61:731-44. [PMID: 27121329 DOI: 10.1038/jhg.2016.38] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 03/16/2016] [Accepted: 03/24/2016] [Indexed: 01/26/2023]
Abstract
Phenylketonuria (PKU), the most common inborn error of amino acid metabolism, is caused by mutations in the phenylalanine-4-hydroxylase (PAH) gene. This study aimed to assess the genotype-phenotype correlation in the PKU Spanish population and the usefulness in establishing genotype-based predictions of BH4 responsiveness in our population. It involved the molecular characterization of 411 Spanish PKU patients: mild hyperphenylalaninemia non-treated (mild HPA-NT) (34%), mild HPA (8.8%), mild-moderate (20.7%) and classic (36.5%) PKU. BH4 responsiveness was evaluated using a 6R-BH4 loading test. We assessed genotype-phenotype associations and genotype-BH4 responsiveness in our population according to literature and classification of the mutations. The mutational spectrum analysis showed 116 distinct mutations, most missense (70.7%) and located in the catalytic domain (62.9%). The most prevalent mutations were c.1066-11G>A (9.7%), p.Val388Met (6.6%) and p.Arg261Gln (6.3%). Three novel mutations (c.61-13del9, p.Ile283Val and p.Gly148Val) were reported. Although good genotype-phenotype correlation was observed, there was no exact correlation for some genotypes. Among the patients monitored for the 6R-BH4 loading test: 102 were responders (87, carried either one or two BH4-responsive alleles) and 194 non-responders (50, had two non-responsive mutations). More discrepancies were observed in non-responders. Our data reveal a great genetic heterogeneity in our population. Genotype is quite a good predictor of phenotype and BH4 responsiveness, which is relevant for patient management, treatment and follow-up.
Collapse
Affiliation(s)
- Luis Aldámiz-Echevarría
- Unit of Metabolism, Cruces University Hospital, BioCruces Health Research Institute, GCV-CIBER de Enfermedades Raras (CIBERER), Plaza de Cruces s/n, Barakaldo, Spain
| | - Marta Llarena
- Unit of Metabolism, Cruces University Hospital, BioCruces Health Research Institute, GCV-CIBER de Enfermedades Raras (CIBERER), Plaza de Cruces s/n, Barakaldo, Spain
| | - María A Bueno
- Metabolic Disorders, Dietetics and Nutrition Unit, Virgen del Rocío University Hospital, Manuel Siurot Avenue s/n, Sevilla, Spain
| | - Jaime Dalmau
- Nutrition and Metabolopathologies Unit, La Fe University Hospital, Bulevar Sur s/n, Valencia, Spain
| | - Isidro Vitoria
- Nutrition and Metabolopathologies Unit, La Fe University Hospital, Bulevar Sur s/n, Valencia, Spain
| | - Ana Fernández-Marmiesse
- Unit of Diagnosis and Treatment of Congenital Metabolic Diseases, Department of Pediatrics, Hospital Clínico Universitario de Santiago de Compostela, CIBERER, Health Research Institute of Santiago de Compostela (IDIS), A Choupana, s/n, Santiago de Compostela, A Coruña, Spain
| | - Fernando Andrade
- Unit of Metabolism, Cruces University Hospital, BioCruces Health Research Institute, GCV-CIBER de Enfermedades Raras (CIBERER), Plaza de Cruces s/n, Barakaldo, Spain
| | - Javier Blasco
- Gastroenterology, Hepatology and Child Nutrition Unit, Carlos Haya University Hospital, Avda. Arroyo de los Ángeles s/n, Málaga, Spain
| | - Carlos Alcalde
- Paediatrics Unit, Río Hortega University Hospital, Valladolid, Spain
| | - David Gil
- Gastroenterology Unit, Virgen de la Arrixaca University Hospital, Ctra. Madrid-Cartagena s/n, El Palmar, Murcia, Spain
| | - María C García
- Metabolic Pathologies Unit, Miguel Servet University Hospital, Zaragoza, Spain
| | | | - Mónica Ruiz
- Paediatrics Unit, Nuestra Señora de la Candelaria University Hospital, Santa Cruz de Tenerife, Spain
| | - María A Ruiz
- Metabolic Pathologies and Neuropaediatrics Unit, Son Espases University Hospital, Palma de Mallorca, Spain
| | - Luis Peña-Quintana
- Paediatric Gastroenterology, Hepatology and Nutrition Unit, Mother and Child Hospital Complex, Avda. Marítima del Sur s/n, Las Palmas de Gran Canaria, Spain
| | - David González
- Metabolic Pathologies Unit, Maternal and Child Hospital, Badajoz, Spain
| | - Felix Sánchez-Valverde
- Gastroenterology and Paediatric Nutrition Unit, Virgen del Camino Hospital, Pamplona, Spain
| | - Lourdes R Desviat
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa CSIC-UAM, CIBERER, IdiPaz, Madrid, Spain
| | - Belen Pérez
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular Severo Ochoa CSIC-UAM, CIBERER, IdiPaz, Madrid, Spain
| | - María L Couce
- Unit of Diagnosis and Treatment of Congenital Metabolic Diseases, Department of Pediatrics, Hospital Clínico Universitario de Santiago de Compostela, CIBERER, Health Research Institute of Santiago de Compostela (IDIS), A Choupana, s/n, Santiago de Compostela, A Coruña, Spain
| |
Collapse
|
18
|
Réblová K, Kulhánek P, Fajkusová L. Computational study of missense mutations in phenylalanine hydroxylase. J Mol Model 2015; 21:70. [PMID: 25750018 DOI: 10.1007/s00894-015-2620-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2014] [Accepted: 02/15/2015] [Indexed: 10/23/2022]
Abstract
Hyperphenylalaninemia (HPA) is one of the most common metabolic disorders. HPA, which is transmitted by an autosomal recessive mode of inheritance, is caused by mutations of the phenylalanine hydroxylase gene. Most mutations are missense and lead to reduced protein stability and/or impaired catalytic function. The impact of such mutations varies, ranging from classical phenylketonuria (PKU), mild PKU, to non-PKU HPA phenotypes. Despite the fact that HPA is a monogenic disease, clinical data show that one PKU genotype can be associated with more in vivo phenotypes, which indicates the role of other (still unknown) factors. To better understand the phenotype-genotype relationships, we analyzed computationally the impact of missense mutations in homozygotes stored in the BIOPKU database. A total of 34 selected homozygous genotypes was divided into two main groups according to their phenotypes: (A) genotypes leading to non-PKU HPA or combined phenotype non-PKU HPA/mild PKU and (B) genotypes leading to classical PKU, mild PKU or combined phenotype mild PKU/classical PKU. Combining in silico analysis and molecular dynamics simulations (in total 3 μs) we described the structural impact of the mutations, which allowed us to separate 32 out of 34 mutations between groups A and B. Testing the simulation conditions revealed that the outcome of mutant simulations can be modulated by the ionic strength. We also employed programs SNPs3D, Polyphen-2, and SIFT but based on the predictions performed we were not able to discriminate mutations with mild and severe PKU phenotypes.
Collapse
Affiliation(s)
- Kamila Réblová
- Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic,
| | | | | |
Collapse
|
19
|
Hagedorn TS, van Berkel P, Hammerschmidt G, Lhotáková M, Saludes RP. Requirements for a minimum standard of care for phenylketonuria: the patients' perspective. Orphanet J Rare Dis 2013; 8:191. [PMID: 24341788 PMCID: PMC3878574 DOI: 10.1186/1750-1172-8-191] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 11/12/2013] [Indexed: 11/22/2022] Open
Abstract
Phenylketonuria (PKU, ORPHA716) is an inherited disorder that affects about one in every 10,000 children born in Europe. Early and continuous application of a modified diet is largely successful in preventing the devastating brain damage associated with untreated PKU. The management of PKU is inconsistent: there are few national guidelines, and these tend to be incomplete and implemented sporadically. In this article, the first-ever pan- European patient/carer perspective on optimal PKU care, the European Society for Phenylketonuria and Allied Disorders (E.S.PKU) proposes recommendations for a minimum standard of care for PKU, to underpin the development of new pan-European guideline for the management of PKU. New standards of best practice should guarantee equal access to screening, treatment and monitoring throughout Europe. Screening protocols and interpretation of screening results should be standardised. Experienced Centres of Expertise are required, in line with current European Union policy, to guarantee a defined standard of multidisciplinary treatment and care for all medical and social aspects of PKU. Women of childbearing age require especially intensive management, due to the risk of severe risks to the foetus conferred by uncontrolled PKU. All aspects of treatment should be reimbursed to ensure uniform access across Europe to guideline-driven, evidence-based care. The E.S.PKU urges PKU healthcare professionals caring for people with PKU to take the lead in developing evidence based guidelines on PKU, while continuing to play an active role in serving as the voice of patients and their families, whose lives are affected by the condition.
Collapse
Affiliation(s)
- Tobias S Hagedorn
- European Society for Phenylketonuria and Allied Disorders (E,S,PKU), Melsele, Belgium.
| | | | | | | | | |
Collapse
|
20
|
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]
|
21
|
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.
Collapse
Affiliation(s)
- Nenad Blau
- University Children's Hospital, Division of Inborn Metabolic Diseases, Department of General Pediatrics, Im Neuenheimer Feld 430, 69120 Heidelberg, Germany.
| |
Collapse
|
22
|
Couce ML, Bóveda MD, Fernández-Marmiesse A, Mirás A, Pérez B, Desviat LR, Fraga JM. Molecular epidemiology and BH4-responsiveness in patients with phenylalanine hydroxylase deficiency from Galicia region of Spain. Gene 2013; 521:100-4. [PMID: 23500595 DOI: 10.1016/j.gene.2013.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 02/28/2013] [Accepted: 03/01/2013] [Indexed: 11/16/2022]
Abstract
Knowledge of hyperphenylalaninemia (HPA) mutational spectrum in a population allows in many cases an accurate prediction of the phenotype and tetrahydrobiopterin (BH4) responsiveness, thus selecting an adequate treatment. In this work, we have performed the molecular characterization of 105 HPA patients from Galicia, in the northwest region of Spain, evaluating their phenotype and BH4 response. The mutational spectrum analysis showed 47 distinct mutations in 89 families, 37 of them (78.7%) corresponding to missense mutations. Six mutations account for 47.2% of all the investigated alleles, each one with a frequency ≥ 5% (IVS10-11G>A, p.R261Q, p.V388M, p.R176L, p.E280K, p.A300S). The most prevalent HPA mutations in Galicia are the common Mediterranean mutation IVS10-11G>A and p.R261Q, with frequencies of 13.8% and 10.5%, respectively. One novel mutation (p.K361Q; c.1081A>C) was also reported. Although a good genotype-phenotype correlation is observed, there is no exact correlation for some genotypes involving mutations p.R261Q, p.I65T or IVS10-11G>A. Forty seven patients were monitored for post-challenge BH4, establishing genotype-based predictions of BH4-responsiveness in all of them. All phenylketonuric patients with 2 nonresponsive mutations were unresponsive to BH4 and patients with mutations previously associated with BH4 responsiveness in the two alleles had a clear positive response to the test, with the exception of 5 patients with mutations p.R261Q, p.I65T and p.R68S. Our study supports a similar degree of heterogeneity of the HPA mutation spectrum in Galicia compared to reported data from Southern Europe. Patients carrying null mutations in both alleles showed the highest degree of concordance with the most severe phenotypes. Genotype is a good predictor of BH4 response.
Collapse
Affiliation(s)
- M L Couce
- Unit of Diagnosis and Treatment of Congenital Metabolic Diseases, Department of Pediatrics, Hospital Clinico Universitario de Santiago, Santiago de Compostela, Spain.
| | | | | | | | | | | | | |
Collapse
|
23
|
Bueno MA, González-Lamuño D, Delgado-Pecellín C, Aldámiz-Echevarría L, Pérez B, Desviat LR, Couce ML. Molecular epidemiology and genotype-phenotype correlation in phenylketonuria patients from South Spain. J Hum Genet 2013; 58:279-84. [PMID: 23514811 DOI: 10.1038/jhg.2013.16] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The aim of this study was to identify the most common genotypes in the phenylketonuria (PKU) population of Andalusia, assessing the correlation with the phenotype and the usefulness in predicting the response to treatment with tetrahydrobiopterin. We conducted a retrospective observational study between January 1980 and January 2010 in 147 Andalusian PKU patients assessing phenotype, genotype and response to a 24-h BH4 loading test. Our cohort of patients exhibited 65 different mutations, 69.2% corresponding to the missense type, in a total of 123 different genotypes. IVS10nt-11g>a was the most common mutation (10.9%). Four novel missense mutations were identified: p.L258P; p.E66K, p.R155C and p.P122S. Although generally there is a good genotype-phenotype correlation, for eight of the repeated genotypes a slightly different phenotype was observed. In 96 PKU subjects BH4 challenge was carried out. Patients with previously reported unresponsive mutations on both alleles showed a negative response, while 95.5% (28/29) of the responsive patients carry at least one missense mutation previously associated to the BH4. Our data reveal a great genetic heterogeneity in the Andalusian population. Genotype is quite a good predictor of the phenotype and of the responsiveness to tetrahydrobiopterin, which is relevant for patient management and follow-up.
Collapse
Affiliation(s)
- María A Bueno
- Unit of Metabolophaties and Nutrition, Department of Pediatrics, Hospital Universitario Virgen del Rocio, Seville, Spain
| | | | | | | | | | | | | |
Collapse
|
24
|
Wiedemann A, Leheup B, Battaglia-Hsu SF, Jonveaux P, Jeannesson E, Feillet F. Undiagnosed phenylketonuria in parents of phenylketonuric patients, is it worthwhile to be checked? Mol Genet Metab 2013; 110 Suppl:S62-5. [PMID: 24051226 DOI: 10.1016/j.ymgme.2013.08.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 08/25/2013] [Accepted: 08/25/2013] [Indexed: 10/26/2022]
Abstract
In our phenylketonuria (PKU) cohort of 120 patients, we uncovered a couple of cases of undiagnosed mild phenylketonuria (mPKU)/hyperphenylalaninemia (mHPA) in maternal parents of the PKU cohort. This finding prompted us to evaluate the risk of either mild phenylketonuria or mild hyperphenylalaninemia in the parent population whose children were diagnosed with hyperphenylalaninemia (HPA). Taking into account the phenylalanine hydroxylase (PAH) mutation carrier frequency and the PAH mild mutation rate, we estimated that the prevalence of the parental mPKU/mHPA varied widely, from 1/74 in Turkey to 1/708 in Lithuania. The benefits of the parental detection procedure described here are the prevention of further maternal PKU syndrome, the follow-up of the newly detected patients and the accuracy of the genetic counseling provided to these families. This very simple procedure should be incorporated into neonatal PKU management of the hospitals in countries where a routine systematic neonatal screening is operational.
Collapse
Affiliation(s)
- A Wiedemann
- CHU Brabois, Pôle Enfants, Service de Pédiatrie et de Génétique Clinique, Vandoeuvre les Nancy 54500, France
| | | | | | | | | | | |
Collapse
|
25
|
Karam PE, Alhamra RS, Nemer G, Usta J. Spectrum of mutations in Lebanese patients with phenylalanine hydroxylase deficiency. Gene 2012; 515:117-22. [PMID: 23220018 DOI: 10.1016/j.gene.2012.11.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 11/15/2012] [Accepted: 11/20/2012] [Indexed: 11/24/2022]
Abstract
Phenylketonuria is an autosomal recessive inborn error of metabolism resulting from phenylalanine hydroxylase deficiency. Genetic basis of phenylalanine hydroxylase deficiency has been reported in various European and Asian countries with few reports available in Arab populations of the Mediterranean region. This is the first pilot study describing phenotype and genotype of 23 Lebanese patients with phenylketonuria. 48% of the patients presented mainly with neurological signs at a mean age of 2 years 9 months, as newborn screening is not yet a nationwide policy. 56.5% of the patients had classical phenylketonuria. Thirteen different mutations were identified: splice site 52%, frameshift 31%, and missense 17% with no nonsense mutations. IVS10-11G>A was found mainly in Christians at high relative frequency whereas Muslims carried the G352fs and R261Q mutations. A rare splice mutation IVS7+1G>T, not described before, was identified in the homozygous state in one family with moderate phenylketonuria phenotype. Genotype-phenotype correlation using Guldberg arbitrary value method showed high consistency between predicted and observed phenotypes. Calculated homozygosity rate was 0.07 indicating the genetic heterogeneity in our patients. Our findings underline the admixture of different ethnicities and religions in Lebanon that might help tracing back the PAH gene flux history across the Mediterranean region.
Collapse
Affiliation(s)
- Pascale E Karam
- Department of Pediatrics and Adolescent, American University Medical Center, Faculty of Medicine, Beirut, Lebanon
| | | | | | | |
Collapse
|
26
|
Gort L, de Olano N, Macías-Vidal J, Coll MJ. GM2 gangliosidoses in Spain: Analysis of the HEXA and HEXB genes in 34 Tay–Sachs and 14 Sandhoff patients. Gene 2012; 506:25-30. [DOI: 10.1016/j.gene.2012.06.080] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 06/21/2012] [Accepted: 06/25/2012] [Indexed: 10/28/2022]
|
27
|
Pajares S, Alcalde C, Couce ML, Del Toro M, González-Meneses A, Guillén E, Pineda M, Pintos G, Gort L, Coll MJ. Molecular analysis of mucopolysaccharidosis IVA (Morquio A) in Spain. Mol Genet Metab 2012; 106:196-201. [PMID: 22521955 DOI: 10.1016/j.ymgme.2012.03.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 03/13/2012] [Accepted: 03/13/2012] [Indexed: 11/21/2022]
Abstract
Mucopolysaccharidosis type IVA (Morquio A) is an inherited metabolic disease with autosomal recessive inheritance. The pathology is due to a deficient activity of N-acetylgalactosamine-6-sulfate-sulfatase, which is involved in the degradation of keratan sulfate and chondroitin-6-sulfate. To date more than 150 mutations have been described in the GALNS gene in different populations. The aim of this study was to analyze the mutations and polymorphisms in Spain in order to know the epidemiology of our population and also to offer genetic counseling to affected families. We found 30 mutant alleles in the 15 families analyzed completing all the genotypes. Most of the mutations that we found were missense mutations, six of which were novel: p.S74F, p.E121D, p.Y254C, p.E260K, p.T394P and p.N495Y; we also found a small deletion (c.1142delC) and a probable deep intronic mutation that causes the loss of exon 5 (c.423_566del) found in cDNA. Both mutations are described in this study for the first time. We also identified 20 polymorphisms previously reported and 2 novel ones: (c.633+222T/C and c.898+25C>G). In conclusion, we have identified the mutations responsible for Mucopolysaccharidosis IV A in Spain. We found great allelic heterogeneity, as occurs in other populations, which hinders the establishment of genotype-phenotype correlations in Spain. This study has been very useful for genetic counseling to the affected families.
Collapse
Affiliation(s)
- Sonia Pajares
- Sección de Errores Congénitos del Metabolismo-IBC, Servicio de Bioquímica y Genética Molecular, Hospital Clínic, CIBERER, IDIBAPS, Barcelona, Spain
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Shi Z, Sellers J, Moult J. Protein stability and in vivo concentration of missense mutations in phenylalanine hydroxylase. Proteins 2011; 80:61-70. [PMID: 21953985 DOI: 10.1002/prot.23159] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 07/21/2011] [Accepted: 07/26/2011] [Indexed: 11/07/2022]
Abstract
A previous computational analysis of missense mutations linked to monogenic disease found a high proportion of missense mutations affect protein stability, rather than other aspects of protein structure and function. The purpose of this study is to relate the presence of such stability damaging missense mutations to the levels of a particular protein present under "in vivo" like conditions, and to test the reliability of the computational methods. Experimental data on a set of missense mutations of the enzyme phenylalanine hydroxylase (PAH) associated with the monogenic disease phenylketonuria (PKU) have been compared with the expected in vivo impact on protein function, obtained using SNPs3D, an in silico analysis package. A high proportion of the PAH mutations are predicted to be destabilizing. The overall agreement between predicted stability impact and experimental evidence for lower protein levels is in accordance with the estimated error rates of the methods. For these mutations, destabilization of protein three-dimensional structure is the major molecular mechanism leading to PKU, and results in a substantial reduction of in vivo PAH protein concentration. Although of limited scale, the results support the view that destabilization is the most common mechanism by which missense mutations cause monogenic disease. In turn, this conclusion suggests the general therapeutic strategy of developing drugs targeted at restoring wild type stability.
Collapse
Affiliation(s)
- Zhen Shi
- Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland 20850, USA
| | | | | |
Collapse
|
29
|
Hanley WB. Non-PKU mild hyperphenylalaninemia (MHP)--the dilemma. Mol Genet Metab 2011; 104:23-6. [PMID: 21632269 DOI: 10.1016/j.ymgme.2011.05.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 05/10/2011] [Accepted: 05/10/2011] [Indexed: 11/24/2022]
Abstract
Recent reviews have suggested that some patients with "non-PKU mild hyperphenylalaninemia" (MHP) might display neuropsychological executive function deficits and should be considered for treatment with tetrahydrobipterin (BH4) and/or phenylalanine (Phe) restricted diet. Patients with phenylketonuria (PKU)--Classical and Mild/Atypical variants--appear to need "mean lifetime phenylalanine (Phe) levels" of 120-360 μmol/L for optimal results. MHP patients, on the other hand, have natural Phe levels of 200-600 μmol/L. Until recently this was thought to be a benign condition. The available literature has been reviewed in detail and no good evidence, to date, has been uncovered to support treatment of MHP. It is suggested that more MHP subjects be tested to confirm this. A plea is made to formulate a consistent world-wide classification of the PKU phenotypes.
Collapse
Affiliation(s)
- W B Hanley
- Division of Clinical Genetics, Department of Paediatrics, The Hospital for Sick Children, 555 University Ave, Toronto, ON, M5G 1X8, Canada.
| |
Collapse
|
30
|
Pérez B, Briones P, Quelhas D, Artuch R, Vega AI, Quintana E, Gort L, Ecay MJ, Matthijs G, Ugarte M, Pérez-Cerdá C. The molecular landscape of phosphomannose mutase deficiency in iberian peninsula: identification of 15 population-specific mutations. JIMD Rep 2011; 1:117-23. [PMID: 23430838 DOI: 10.1007/8904_2011_26] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Revised: 02/11/2011] [Accepted: 02/16/2011] [Indexed: 03/25/2023] Open
Abstract
PMM2-CDG is an autosomal recessive disorder and the most frequent form of congenital disorder of N-glycosylation, with more than 100 mutations identified to date. Sixty-six patients from 58 unrelated families were diagnosed as PMM2-CDG (CDG-Ia) based on clinical signs or because of a previous affected sibling. They all presented a type 1 serum transferrin isoform pattern, and, in most cases, the disease was confirmed by determining PMM2 activity in fibroblasts and/or lymphocytes. Residual PMM2 activity in fibroblasts ranged from not detectable to 60% of the mean controls. DNA and RNA were isolated from fresh blood or fibroblasts from patients to perform molecular studies of the PMM2 gene, resulting in the identification of 30 different mutations, four of them newly reported here (p.Y102C, p.T118S, p.P184T, and p.D209G). From these 30 mutations, 15 have only been identified among Iberian PMM2-CDG patients. As in other Caucasian populations, p.R141H was the most frequent mutation (24 alleles, prevalence 20.6%), but less than in other European series in which this mutation represents 35-43% of the disease alleles. The next frequent mutations were p.D65Y (12 alleles, prevalence 10.3%) and p.T237M (9 alleles, prevalence 7.6%), while p.F119L and p.E139K, the most frequent changes in Scandinavian and French populations, respectively, were not found in our patients. The most common genotype was [p.R141H] + [p.T237M], and four homozygous patients for p.Y64C, p.D65Y, p.P113L, and p.T237M were detected. The broad mutational spectrum and the diversity of phenotypes found in the Iberian populations hamper genotype-phenotype correlation.
Collapse
Affiliation(s)
- B Pérez
- Centro de Diagnóstico de Enfermedades Moleculares, CBM-SO, Facultad de Ciencias, Módulo 10, Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Abstract
Phenylketonuria is the most prevalent disorder caused by an inborn error in aminoacid metabolism. It results from mutations in the phenylalanine hydroxylase gene. Phenotypes can vary from a very mild increase in blood phenylalanine concentrations to a severe classic phenotype with pronounced hyperphenylalaninaemia, which, if untreated, results in profound and irreversible mental disability. Neonatal screening programmes identify individuals with phenylketonuria. The initiation of a phenylalanine-restricted diet very soon after birth prevents most of the neuropsychological complications. However, the diet is difficult to maintain and compliance is often poor, especially in adolescents, young adults, and pregnant women. Tetrahydrobiopterin stimulates phenylalanine hydroxylase activity in about 20% of patients, and in those patients serves as a useful adjunct to the phenylalanine-restricted diet because it increases phenylalanine tolerance and allows some dietary freedom. Possible future treatments include enzyme substitution with phenylalanine ammonia lyase, which degrades phenylalanine, and gene therapy to restore phenylalanine hydroxylase activity.
Collapse
Affiliation(s)
- Nenad Blau
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital, Zurich, Switzerland.
| | | | | |
Collapse
|
32
|
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.
Collapse
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
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Dahri S, Desviat LR, Pérez B, Leal F, Ugarte M, Chabraoui L. Mutation analysis of phenylketonuria patients from Morocco: high prevalence of mutation G352fsdelG and detection of a novel mutation p.K85X. Clin Biochem 2009; 43:76-81. [PMID: 19786003 DOI: 10.1016/j.clinbiochem.2009.09.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 09/15/2009] [Accepted: 09/16/2009] [Indexed: 11/19/2022]
Abstract
OBJECTIVE The knowledge of the molecular basis of the Phenylketonuria (PKU, MIM# 261600) in different countries provides relevant information for undertaking specific and rational mutation detection strategies in each population and for the implementation of adequate dietary and cofactor treatment. There are no data available in Moroccan population. DESIGN AND METHODS In this work we describe the genetic analysis by mutation scanning using denaturing gradient gel electrophoresis (DGGE) and subsequent direct sequencing of 20 different PKU families from Morocco. We have also included the study of 7 Moroccan PKU patients living in Spain detected by the Spanish newborn screening program. RESULTS The mutational spectrum in the first sample included eight different changes, one of them, p.K85X, was novel. The most common mutation was the frame shift change p.G352fsdelG identified in 62.5% of the mutant chromosomes studied. Other changes (p.R176X, IVS10nt-11 g>a, p.W120X, p.A165T, p.R243X and p.R243Q) were identified, respectively, in 2 or 3 mutant alleles. All detected mutations were severe according to the classical phenotype of the patients. In the 7 patients living in Spain we have detected 4 severe mutations (p.G352fs, p.R176X, Y198fs and Exon3del) and also milder changes such as p.A403V, p.S196T, p.D145V and p.R408Q detected in 3 mild hyperphenylalaninemia (MHP) patients and a novel p.L258P found in a mild PKU patient. CONCLUSION The results provide important information on the distribution of PKU mutations in this Mediterranean area gaining insight into the genetic epidemiology of the disease.
Collapse
Affiliation(s)
- Saloua Dahri
- Service de Biochimie, Centre d'Etudes des Maladies Héréditaires du Métabolisme, Hôpital d'Enfants de Rabat et Faculté de Médecine et de Pharmacie, Université Mohammed V Souissi, Rabat, Moroccco
| | | | | | | | | | | |
Collapse
|
34
|
Ahring K, Bélanger-Quintana A, Dokoupil K, Gokmen Ozel H, Lammardo AM, MacDonald A, Motzfeldt K, Nowacka M, Robert M, van Rijn M. Dietary management practices in phenylketonuria across European centres. Clin Nutr 2009; 28:231-6. [PMID: 19362397 DOI: 10.1016/j.clnu.2009.03.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 03/06/2009] [Accepted: 03/15/2009] [Indexed: 11/25/2022]
Abstract
BACKGROUND Dietary phenylalanine restriction is the cornerstone of phenylketonuria (PKU) management. However, there are no European consensus guidelines for its optimal dietary care. METHODS Detailed information on the routine dietary management of PKU was obtained from 10 European centres using structured questionnaires. Each centre was represented by one dietitian/nutritionist or physician (European Nutritionist Expert Panel). RESULTS All centres screened for PKU within the first 10 days of life. PKU prevalence was highest in Turkey. The training, roles and responsibilities of dietitians and nutritionists varied widely; in some centres dietitians were responsible for managing the diet, while in others this was performed by a physician. There were marked differences in target blood phenylalanine concentrations, the dosages of protein substitutes, systems for allocating daily phenylalanine allowance, and the definition of foods that could be eaten without restriction ('free foods'). Eighty percent (n=8/10) of centres encouraged breastfeeding together with protein substitute in infants with PKU. CONCLUSIONS Important differences exist among centres across Europe in the dietary management of PKU, and in support systems designed to assist patients in managing their diets. Further studies are needed to compare different dietary treatments with the aim of identifying best practice to optimise phenylalanine control and dietary adherence.
Collapse
|
35
|
De Lucca M, Arias I, Casique L, Araujo K, Merzon RM. Improving phenylketonuria genotyping by screening for the IVS4+5g>t mutation in the PAH gene. Clin Chim Acta 2009; 402:206-8. [DOI: 10.1016/j.cca.2008.10.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Revised: 10/24/2008] [Accepted: 10/25/2008] [Indexed: 10/21/2022]
|
36
|
Sarkissian CN, Gámez A, Scriver CR. What we know that could influence future treatment of phenylketonuria. J Inherit Metab Dis 2009; 32:3-9. [PMID: 18668342 DOI: 10.1007/s10545-008-0917-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2008] [Revised: 06/10/2008] [Accepted: 06/11/2008] [Indexed: 11/25/2022]
Abstract
Phenylketonuria (PKU), a Mendelian autosomal recessive phenotype (OMIM 261600), is an inborn error of metabolism that can result in impaired postnatal cognitive development. The phenotypic outcome is multifactorial in origin, based both in nature, the mutations in the gene encoding the L-phenylalanine hydroxylase enzyme, and nurture, the nutritional experience introducing L-phenylalanine into the diet. The PKU story contains many messages including a framework to appreciate the complexity of this disease where phenotype reflects both locus-specific and genomic components. This knowledge is now being applied in the development of patient-specific therapies.
Collapse
Affiliation(s)
- C N Sarkissian
- Department of Biology, Human Genetics and Pediatrics, McGill University, Quebec, Canada.
| | | | | |
Collapse
|
37
|
Zschocke J, Aulehla-Scholz C, Patton S. Quality of diagnostic mutation analyses for phenylketonuria. J Inherit Metab Dis 2008; 31:697-702. [PMID: 19015950 DOI: 10.1007/s10545-008-1052-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 10/14/2008] [Accepted: 10/16/2008] [Indexed: 10/21/2022]
Abstract
DNA sequence analyses have become a major component in the diagnostic work-up of patients; however, limited consideration appears to be given to the possibility that reported results may in fact be wrong. Over the last four years we have carried out an External Quality Assessment scheme for mutation analysis in phenylketonuria. Each year, three DNA samples with previously characterized genotypes were mailed to participating laboratories. Indications for testing were either confirmation of diagnosis and prediction of disease severity, or carrier analysis. Each year there were several laboratories that failed to identify mutations because of methodological limitations. Of the participating laboratories that used comprehensive mutation detection methods, each year there was at least one that missed at least one mutation. Indeed, in the 2007 scheme almost 8% of reports from laboratories that used comprehensive mutation detection methods such as sequencing of all exons of the PAH gene contained incorrect genotypes. There were also serious deficiencies in the interpretation of genotype data: in the 2007 scheme, 6 out of 10 laboratories that obtained full genotyping marks for interpretation incurred a reduction of marks because information on the expected phenotype was missing or wrong. Several laboratories failed to appreciate the clinical relevance of a mutation associated with mild hyperphenylalaninaemia, which does not require treatment, and some discussed the option of prenatal diagnosis in the respective case. In conclusion, mutation analyses may be prone to errors and this demands careful interpretation of results in relation to clinical and biochemical findings.
Collapse
Affiliation(s)
- J Zschocke
- Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.
| | | | | |
Collapse
|
38
|
Pey AL, Stricher F, Serrano L, Martinez A. Predicted effects of missense mutations on native-state stability account for phenotypic outcome in phenylketonuria, a paradigm of misfolding diseases. Am J Hum Genet 2007; 81:1006-24. [PMID: 17924342 PMCID: PMC2265664 DOI: 10.1086/521879] [Citation(s) in RCA: 140] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Accepted: 07/25/2007] [Indexed: 12/15/2022] Open
Abstract
Phenylketonuria (PKU) is a genetic disease caused by mutations in human phenylalanine hydroxylase (PAH). Most missense mutations result in misfolding of PAH, increased protein turnover, and a loss of enzymatic function. We studied the prediction of the energetic impact on PAH native-state stability of 318 PKU-associated missense mutations, using the protein-design algorithm FoldX. For the 80 mutations for which expression analyses have been performed in eukaryote systems, in most cases we found substantial overall correlations between the mutational energetic impact and both in vitro residual activities and patient metabolic phenotype. This finding confirmed that the decrease in protein stability is the main molecular pathogenic mechanism in PKU and the determinant for phenotypic outcome. Metabolic phenotypes have been shown to be better predicted than in vitro residual activities, probably because of greater stringency in the phenotyping process. Finally, all the remaining 238 PKU missense mutations compiled at the PAH locus knowledgebase (PAHdb) were analyzed, and their phenotypic outcomes were predicted on the basis of the energetic impact provided by FoldX. Residues in exons 7-9 and in interdomain regions within the subunit appear to play an important structural role and constitute hotspots for destabilization. FoldX analysis will be useful for predicting the phenotype associated with rare or new mutations detected in patients with PKU. However, additional factors must be considered that may contribute to the patient phenotype, such as possible effects on catalysis and interindividual differences in physiological and metabolic processes.
Collapse
Affiliation(s)
- Angel L Pey
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | | | | |
Collapse
|
39
|
Abstract
"Inborn errors of metabolism," first recognized 100 years ago by Garrod, were seen as transforming evidence for chemical and biological individuality. Phenylketonuria (PKU), a Mendelian autosomal recessive phenotype, was identified in 1934 by Asbjörn Fölling. It is a disease with impaired postnatal cognitive development resulting from a neurotoxic effect of hyperphenylalaninemia (HPA). Its metabolic phenotype is accountable to multifactorial origins both in nurture, where the normal nutritional experience introduces L-phenylalanine, and in nature, where mutations (>500 alleles) occur in the phenylalanine hydroxylase gene (PAH) on chromosome 12q23.2 encoding the L-phenylalanine hydroxylase enzyme (EC 1.14.16.1). The PAH enzyme converts phenylalanine to tyrosine in the presence of molecular oxygen and catalytic amounts of tetrahydrobiopterin (BH4), its nonprotein cofactor. PKU is among the first of the human genetic diseases to enter, through newborn screening, the domain of public health, and to show a treatment effect. This effect caused a paradigm shift in attitudes about genetic disease. The PKU story contains many messages, including: a framework on which to appreciate the complexity of PKU in which phenotype reflects both locus-specific and genomic components; what the human PAH gene tells us about human population genetics and evolution of modern humans; and how our interest in PKU is served by a locus-specific mutation database (http://www.pahdb.mcgill.ca; last accessed 20 March 2007). The individual Mendelian PKU phenotype has no "simple" or single explanation; every patient has her/his own complex PKU phenotype and will be treated accordingly. Knowledge about PKU reveals genomic components of both disease and health.
Collapse
Affiliation(s)
- Charles R Scriver
- Department of Human Genetics, Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
| |
Collapse
|
40
|
Gort L, Boleda MD, Tyfield L, Vilarinho L, Rivera I, Cardoso ML, Santos-Leite M, Girós M, Briones P. Mutational spectrum of classical galactosaemia in Spain and Portugal. J Inherit Metab Dis 2006; 29:739-42. [PMID: 17041746 DOI: 10.1007/s10545-006-0356-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Revised: 09/04/2006] [Accepted: 09/20/2006] [Indexed: 11/26/2022]
Abstract
Classical galactosaemia is an autosomal recessive inherited metabolic disorder due to deficient galactose-1-phosphate uridyltransferase (GALT). Over 180 different base changes and disease-causing mutations have been reported in the GALT gene. Mutation p.Q188R was found to be the most common molecular defect among caucasian classical galactosaemia patients. We have characterized the spectrum of GALT mutations in a group of 51 Spanish families and 32 Portuguese families with this disease. p.Q188R is also the most prevalent mutation in the Spanish and Portuguese population, accounting for 50% and 57.8% of galactosaemic alleles, respectively. An additional 15 mutations were also identified in Spanish patients, four of which were novel: p.D28H, p.S181A, c.658dupG and c.377+53_1059+87del. In the Portuguese population, 11 different mutations were found, three of which were novel: p.R33H, p.P185S, and p.S192G. The differences observed between the genotypes identified in Portuguese and Spanish galactosaemic populations are notable. Only mutations p.Q188R, p.R148Q and c.820+13g>a were identified in both populations. In spite of the geographical proximity of Spain and Portugal, it seems that they have received genetic influences from different populations. The repeated migrations that occurred in the Iberian Peninsula throughout centuries may explain such variability.
Collapse
Affiliation(s)
- L Gort
- Institut de Bioquímica Clínica, Corporació Sanitària Clínic, Barcelona, Spain
| | | | | | | | | | | | | | | | | |
Collapse
|
41
|
Desviat LR, Pérez B, Ugarte M. Identification of exonic deletions in the PAH gene causing phenylketonuria by MLPA analysis. Clin Chim Acta 2006; 373:164-7. [PMID: 16875683 DOI: 10.1016/j.cca.2006.05.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Revised: 04/27/2006] [Accepted: 05/03/2006] [Indexed: 11/18/2022]
Abstract
BACKGROUND Multiplex ligation probe amplification (MLPA) is a sensitive and efficient technique for molecular diagnosis of diseases involving deletions or duplications of large genomic regions. In phenylketonuria (PKU), most of the mutant alleles correspond to missense mutations and large deletions have been scarcely identified. In this study, we report for the first time the use of MLPA analysis on PKU patients to detect exonic deletions. METHOD DNA from 22 unrelated PKU patients with an incomplete genetic diagnosis after standard mutation detection analysis were subjected to MLPA analysis. Deletions were confirmed by long-range PCR and sequence analysis. RESULTS The technique identified two large genomic deletions in the phenylalanine hydroxylase (PAH) gene, of 6.6 kb and 1.8 kb, including exons 3 and 5, respectively. The chromosomal breakpoints were established by long-range PCR and chromosomal walking, confirming the involvement of repetitive sequences in the deletions. CONCLUSION MLPA may complement routine mutation screening in PKU patients, although, in the sample studied, exonic deletions in the PAH gene do not appear to be a frequent cause of PKU.
Collapse
Affiliation(s)
- Lourdes R Desviat
- Centro de Biología Molecular Severo Ochoa CSIC-UAM, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | | | | |
Collapse
|
42
|
Desviat LR, Pérez B, Bèlanger-Quintana A, Castro M, Aguado C, Sánchez A, García MJ, Martínez-Pardo M, Ugarte M. Tetrahydrobiopterin responsiveness: results of the BH4 loading test in 31 Spanish PKU patients and correlation with their genotype. Mol Genet Metab 2004; 83:157-62. [PMID: 15464430 DOI: 10.1016/j.ymgme.2004.06.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2004] [Revised: 06/12/2004] [Accepted: 06/16/2004] [Indexed: 11/25/2022]
Abstract
Tetrahydrobiopterin (BH4) responsiveness in patients with mutations in the phenylalanine hydroxylase (PAH) gene is a recently recognized subtype of hyperphenylalaninemia characterized by a positive BH4 loading test. According to recent estimates, this phenotype may be quite common, suggesting that a large group of individuals may benefit from BH4 substitution, eliminating the need of life-long dietary restrictions. This underscores the importance of identifying BH4-responsive patients in each population, establishing the association with specific PAH mutations. In this work, we describe the results of a pilot study performed with 31 Spanish PAH-deficient patients subjected to a BH4 loading test. Overall, 11/31 (37%) showed a positive response with a 30% decrease in blood Phe levels 8 h after the BH4 challenge, and three additional patients, considered slow responders, showed this decrease only after 12-16 h. We report for the first time a patient homozygous for a splicing mutation with a slow response, suggesting an effect of BH4 supplementation on PAH gene expression. Most of the responsive patients belong to the mild hyperphenylalaninemia (MHP) or mild phenylketonuria phenotypic groups. In MHP patients we report for the first time the results of parallel single Phe doses confirming the utility of these analyses for a better evaluation of the response. Genotype analysis confirms the involvement in the response of specific mutations (D415N, S87R, R176L, E390G, and A309V) present in hemizygous patients, and provide relevant information for the discussion of the potential mechanisms underlying BH4 responsiveness.
Collapse
|
43
|
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.
Collapse
|
44
|
Scriver CR, Hurtubise M, Konecki D, Phommarinh M, Prevost L, Erlandsen H, Stevens R, Waters PJ, Ryan S, McDonald D, Sarkissian C. PAHdb 2003: what a locus-specific knowledgebase can do. Hum Mutat 2003; 21:333-44. [PMID: 12655543 DOI: 10.1002/humu.10200] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
PAHdb, a legacy of and resource in genetics, is a relational locus-specific database (http://www.pahdb.mcgill.ca). It records and annotates both pathogenic alleles (n = 439, putative disease-causing) and benign alleles (n = 41, putative untranslated polymorphisms) at the human phenylalanine hydroxylase locus (symbol PAH). Human alleles named by nucleotide number (systematic names) and their trivial names receive unique identifier numbers. The annotated gDNA sequence for PAH is typical for mammalian genes. An annotated gDNA sequence is numbered so that cDNA and gDNA sites are interconvertable. A site map for PAHdb leads to a large array of secondary data (attributes): source of the allele (submitter, publication, or population); polymorphic haplotype background; and effect of the allele as predicted by molecular modeling on the phenylalanine hydroxylase enzyme (EC 1.14.16.1) or by in vitro expression analysis. The majority (63%) of the putative pathogenic PAH alleles are point mutations causing missense in translation of which few have a primary effect on PAH enzyme kinetics. Most apparently have a secondary effect on its function through misfolding, aggregation, and intracellular degradation of the protein. Some point mutations create new splice sites. A subset of primary PAH mutations that are tetrahydrobiopterin-responsive is highlighted on a Curators' Page. A clinical module describes the corresponding human clinical disorders (hyperphenylalaninemia [HPA] and phenylketonuria [PKU]), their inheritance, and their treatment. PAHdb contains data on the mouse gene (Pah) and on four orthologous mutant mouse models and their use (for example, in research on oral treatment of PKU with the enzyme phenylalanine ammonia lyase [EC 4.3.1.5]).
Collapse
Affiliation(s)
- Charles R Scriver
- Department of Human Genetics, McGill University Health Centre, Montreal, Canada.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Pey AL, Desviat LR, Gámez A, Ugarte M, Pérez B. Phenylketonuria: genotype-phenotype correlations based on expression analysis of structural and functional mutations in PAH. Hum Mutat 2003; 21:370-8. [PMID: 12655546 DOI: 10.1002/humu.10198] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
When analyzed in the context of the phenylalanine hydroxylase (PAH) three-dimensional structure, only a minority of the PKU mutations described world-wide affect catalytic residues. Consistent with these observations, recent data point to defective folding and subsequent aggregation/degradation as a predominant disease mechanism for several mutations. In this work, we use a combined approach of expression in eukaryotic cells at different temperatures and a prokaryotic system with co-expression of chaperonins to elucidate and confirm structural consequences for 18 PKU mutations. Three mutations are located in the amino terminal regulatory domain and 15 in the catalytic domain. Four mutations were found to abolish the specific activity in all conditions. Two are catalytic mutations (Y277D and E280K) and two are severe structural defects (IVS10-11G>A and L311P). All the remaining mutations (D59Y, I65T, E76G, P122Q, R158Q, G218V, R243Q, P244L, R252W, R261Q, A309V, R408Q, R408W, and Y414C) are folding defects causing reduced stability and accelerated degradation, although some of them probably affect residues involved in regulation. In these cases, we have demonstrated that the amount of mutant PAH protein and residual activity could be modulated by in vitro experimental conditions, and therefore the observed in vivo metabolic variation may be explained by interindividual variation in the quality control systems. The results derived provide an experimental framework to define the mutation severity relating genotype to phenotype. They also explain the observed inconsistencies for some mutations in patients with similar genotype and different phenotypes.
Collapse
Affiliation(s)
- Angel L Pey
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
| | | | | | | | | |
Collapse
|
46
|
Tighe O, Dunican D, O'Neill C, Bertorelle G, Beattie D, Graham C, Zschocke J, Cali F, Romano V, Hrabincova E, Kozak L, Nechyporenko M, Livshits L, Guldberg P, Jurkowska M, Zekanowski C, Perez B, Desviat LR, Ugarte M, Kucinskas V, Knappskog P, Treacy E, Naughten E, Tyfield L, Byck S, Scriver CR, Mayne PD, Croke DT. Genetic diversity within the R408W phenylketonuria mutation lineages in Europe. Hum Mutat 2003; 21:387-93. [PMID: 12655548 DOI: 10.1002/humu.10195] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The R408W phenylketonuria mutation in Europe has arisen by recurrent mutation in the human phenylalanine hydroxylase (PAH) locus and is associated with two major PAH haplotypes. R408W-2.3 exhibits a west-to-east cline of relative frequency reaching its maximum in the Balto-Slavic region, while R408W-1.8 exhibits an east-to-west cline peaking in Connacht, the most westerly province of Ireland. Spatial autocorrelation analysis has demonstrated that the R408W-2.3 cline, like that of R408W-1.8, is consistent with a pattern likely to have been established by human dispersal. Genetic diversity within wild-type and R408W chromosomes in Europe was assessed through variable number tandem repeat (VNTR) nucleotide sequence variation and tetranucleotide short tandem repeat (STR) allelic associations. Wild-type VNTR-8 chromosomes exhibited two major cassette sequence organizations: (a1)5-b3-b2-c1 and (a1)5-b5-b2-c1. R408W-1.8 was predominantly associated with (a1)5-B5-B2-C1. Both wild-type vntr-3 and r408w-2.3 chromosomes exhibited a single invariant cassette sequence organization, a2-b2-c1. STR allele distributions associated with the cassette variants were consistent with greater diversity in the wild-type VNTR-8 lineage and were suggestive of different levels of diversity between R408W-1.8 and R408W-2.3. The finding of greater genetic diversity within the wild-type VNTR-8 lineage compared to VNTR-3 suggests that VNTR-8 may be older within the European population. However, in the absence of a more extensive STR data-set, no such conclusions are possible for the respective R408W mutant lineages.
Collapse
Affiliation(s)
- Orna Tighe
- Department of Pathology and National Centre for Newborn Screening, The Children's University Hospital, Dublin, Ireland
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
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.
Collapse
Affiliation(s)
- Johannes Zschocke
- Institut für Humangenetik, Ruprecht-Karls-Universität, Heidelberg, Germany.
| |
Collapse
|
48
|
Gámez A, Pérez B, Ugarte M, Desviat LR. Expression analysis of phenylketonuria mutations. Effect on folding and stability of the phenylalanine hydroxylase protein. J Biol Chem 2000; 275:29737-42. [PMID: 10875932 DOI: 10.1074/jbc.m003231200] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phenylketonuria is an autosomal recessive human genetic disease caused by mutations in the phenylalanine hydroxylase (PAH) gene. In the present work we have used different expression systems to reveal folding defects of the PAH protein caused by phenylketonuria mutations L348V, S349L, and V388M. The amount of mutant proteins and/or the residual activity can be rescued by chaperonin co-overexpression in Escherichia coli or growth at low temperature in COS cells. Thermal stability profiles and degradation time courses of PAH expressed in E. coli show that the mutant proteins are less stable than the wild-type enzyme, also confirmed by pulse-chase experiments using a coupled in vitro transcription-translation system. Size exclusion chromatography shows altered oligomerization, partially corrected with chaperonins coexpression, except for the S349L mutant protein, which is recovered as inactive aggregates. PAH subunit interaction is affected in the S349L protein, as demonstrated in a mammalian two-hybrid assay. In conclusion, serine 349, located in the three-dimensional structure lining the active site and involved in the structural maintenance of the iron binding site, is essential for the structural stability and assembly and also for the catalytic properties of the PAH enzyme, whereas the L348V and V388M mutations affect the folding properties and stability of the protein. The experimental modulation of mutant residual activity provides a potential explanation for the existing inconsistencies in the genotype-phenotype correlations.
Collapse
Affiliation(s)
- A Gámez
- Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas-Universidad Autónoma de Madrid, 28049 Madrid, Spain
| | | | | | | |
Collapse
|