1
|
Jalali H, Zamanfar D, Amirzadegan M, Ghadami F, Mahdavi M, Mahdavi MR. Mutation Analysis of PAH Gene in Phenylketonuria Patients from the North of Iran: Identification of Three Novel Pathogenic Variants. Int J Prev Med 2024; 15:22. [PMID: 39170926 PMCID: PMC11338363 DOI: 10.4103/ijpvm.ijpvm_50_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 02/20/2024] [Indexed: 08/23/2024] Open
Abstract
Background There are more than 1100 different pathogenic variants in the phenylalanine hydroxylase (PAH) gene that are responsible for phenylketonuria (PKU) diseases, and the spectrum of these mutations varies in different ethnic groups. The aim of the present study was to identify the frequency of pathogenic variants in all 13 exons of the PAH gene among patients with PKU in Mazandaran and Golestan provinces in the north of Iran. Methods Forty unrelated PKU patients from Mazandaran and Golestan provinces were enrolled in the study. Genomic DNA was extracted from leukocytes using a Qiagen DNA extraction kit and polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP), and Sanger sequencing methods were applied to detect the variants. In the case of new variants, the InterVar online tool (PMID: 28132688) was used to classify the variants. Results Twenty-one different pathogenic variants were observed among the 40 investigated patients. The c.106611G>A variant had the highest frequency (27.5%) in the region, and the c.168+5G>C, c.473G>A, and c.782 G>A variants were the other most frequent mutations with allelic frequencies of 7.5, 5, and 5%, respectively. Three novel pathogenic variants including c.773T>G, c.878 T>C, and c. 1245del variants were observed among the investigated patients. Conclusions The introduction of pathogenic variants in the PAH gene in each ethnic group provides valuable data regarding the understanding of the pathogenesis of the disease and can be helpful for prenatal diagnosis programs.
Collapse
Affiliation(s)
- Hossein Jalali
- Thalassemia Research Center, Hemoglobinopathies Institute, Mazandaran University of Medical Sciences, Sari, Iran
| | - Daniel Zamanfar
- Diabetes Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | | | - Farshide Ghadami
- Diabetes Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Mahan Mahdavi
- Diabetes Research Center, Mazandaran University of Medical Sciences, Sari, Iran
| | - Mohammad Reza Mahdavi
- Thalassemia Research Center, Hemoglobinopathies Institute, Mazandaran University of Medical Sciences, Sari, Iran
| |
Collapse
|
2
|
Pang YH, Gao XY, Yuan ZY, Huang H, Wang ZQ, Peng L, Li YQ, Liu J, Liu D, Chen GR. [ In vitro expression and functional analyses of the mutants p.R243Q, p.R241C and p.Y356X of the human phenylalanine hydroxylase]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2024; 26:188-193. [PMID: 38436318 PMCID: PMC10921879 DOI: 10.7499/j.issn.1008-8830.2309035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 01/08/2024] [Indexed: 03/05/2024]
Abstract
OBJECTIVES To study the in vitro expression of three phenylalanine hydroxylase (PAH) mutants (p.R243Q, p.R241C, and p.Y356X) and determine their pathogenicity. METHODS Bioinformatics techniques were used to predict the impact of PAH mutants on the structure and function of PAH protein. Corresponding mutant plasmids of PAH were constructed and expressed in HEK293T cells. Quantitative reverse transcription polymerase chain reaction was used to measure the mRNA expression levels of the three PAH mutants, and their protein levels were assessed using Western blot and enzyme-linked immunosorbent assay. RESULTS Bioinformatics analysis predicted that all three mutants were pathogenic. The mRNA expression levels of the p.R243Q and p.R241C mutants in HEK293T cells were similar to the mRNA expression level of the wild-type control (P>0.05), while the mRNA expression level of the p.Y356X mutant significantly decreased (P<0.05). The PAH protein expression levels of all three mutants were significantly reduced compared to the wild-type control (P<0.05). The extracellular concentration of PAH protein was reduced in the p.R241C and p.Y356X mutants compared to the wild-type control (P<0.05), while there was no significant difference between the p.R243Q mutant and the wild type control (P>0.05). CONCLUSIONS p.R243Q, p.R241C and p.Y356X mutants lead to reduced expression levels of PAH protein in eukaryotic cells, with p.R241C and p.Y356X mutants also affecting the function of PAH protein. These three PAH mutants are to be pathogenic.
Collapse
Affiliation(s)
- Yong-Hong Pang
- Xuzhou Maternity and Child Health Care Hospital Affiliated to Xuzhou Medical University, Xuzhou, Jiangsu 221009, China (yhpang007@163. com)
| | | | - Zhen-Ya Yuan
- Xuzhou Maternity and Child Health Care Hospital Affiliated to Xuzhou Medical University, Xuzhou, Jiangsu 221009, China (yhpang007@163. com)
| | - Hui Huang
- Xuzhou Maternity and Child Health Care Hospital Affiliated to Xuzhou Medical University, Xuzhou, Jiangsu 221009, China (yhpang007@163. com)
| | - Zeng-Qin Wang
- Xuzhou Maternity and Child Health Care Hospital Affiliated to Xuzhou Medical University, Xuzhou, Jiangsu 221009, China (yhpang007@163. com)
| | - Lei Peng
- Xuzhou Maternity and Child Health Care Hospital Affiliated to Xuzhou Medical University, Xuzhou, Jiangsu 221009, China (yhpang007@163. com)
| | - Yi-Qun Li
- Xuzhou Maternity and Child Health Care Hospital Affiliated to Xuzhou Medical University, Xuzhou, Jiangsu 221009, China (yhpang007@163. com)
| | - Jie Liu
- Xuzhou Maternity and Child Health Care Hospital Affiliated to Xuzhou Medical University, Xuzhou, Jiangsu 221009, China (yhpang007@163. com)
| | - Dong Liu
- Xuzhou Maternity and Child Health Care Hospital Affiliated to Xuzhou Medical University, Xuzhou, Jiangsu 221009, China (yhpang007@163. com)
| | - Gui-Rong Chen
- Xuzhou Maternity and Child Health Care Hospital Affiliated to Xuzhou Medical University, Xuzhou, Jiangsu 221009, China (yhpang007@163. com)
| |
Collapse
|
3
|
Thau-Zuchman O, Pallier PN, Savelkoul PJM, Kuipers AAM, Verkuyl JM, Michael-Titus AT. High phenylalanine concentrations induce demyelination and microglial activation in mouse cerebellar organotypic slices. Front Neurosci 2022; 16:926023. [PMID: 36248632 PMCID: PMC9559601 DOI: 10.3389/fnins.2022.926023] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 09/05/2022] [Indexed: 11/29/2022] Open
Abstract
Phenylketonuria (PKU) is an inborn error of metabolism. Mutations in the enzyme phenylalanine hydroxylase (PAH)-encoding gene lead to a decreased metabolism of the amino acid phenylalanine (Phe). The deficiency in PAH increases Phe levels in blood and brain. Accumulation of Phe can lead to delayed development, psychiatric problems and cognitive impairment. White matter (WM) damage is a neuropathological hallmark of PKU and can be seen even in early detected and treated PKU patients. The mechanisms linking high Phe concentrations to WM abnormalities remain unclear. We tested the effects of high Phe concentrations on myelin in three in vitro models of increasing complexity: two simple cell culture models and one model that preserves local brain tissue architecture, a cerebellar organotypic slice culture prepared from postnatal day (P) 8 CD-1 mice. Various Phe concentrations (0.1–10 mM) and durations of exposure were tested. We found no toxic effect of high Phe in the cell culture models. On the contrary, the treatment promoted the maturation of oligodendrocytes, particularly at the highest, non-physiological Phe concentrations. Exposure of cerebellar organotypic slices to 2.4 mM Phe for 21 days in vitro (DIV), but not 7 or 10 DIV, resulted in a significant decrease in myelin basic protein (MBP), calbindin-stained neurites, and neurites co-stained with MBP. Following exposure to a toxic concentration of Phe, a switch to the control medium for 7 days did not lead to remyelination, while very active remyelination was seen in slices following demyelination with lysolecithin. An enhanced number of microglia, displaying an activated type morphology, was seen after exposure of the slices to 2.4 mM Phe for 10 or 21 DIV. The results suggest that prolonged exposure to high Phe concentrations can induce microglial activation preceding significant disruption of myelin.
Collapse
Affiliation(s)
- Orli Thau-Zuchman
- Centre for Neuroscience, Surgery and Trauma, Barts and The London School of Medicine and Dentistry, The Blizard Institute, Queen Mary University of London, London, United Kingdom
| | - Patrick N. Pallier
- Centre for Neuroscience, Surgery and Trauma, Barts and The London School of Medicine and Dentistry, The Blizard Institute, Queen Mary University of London, London, United Kingdom
- *Correspondence: Patrick N. Pallier,
| | | | | | | | - Adina T. Michael-Titus
- Centre for Neuroscience, Surgery and Trauma, Barts and The London School of Medicine and Dentistry, The Blizard Institute, Queen Mary University of London, London, United Kingdom
| |
Collapse
|
4
|
The Utility of Genomic Testing for Hyperphenylalaninemia. J Clin Med 2022; 11:jcm11041061. [PMID: 35207333 PMCID: PMC8879487 DOI: 10.3390/jcm11041061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/08/2022] [Accepted: 02/16/2022] [Indexed: 12/10/2022] Open
Abstract
Hyperphenylalaninemia (HPA), the most common amino acid metabolism disorder, is caused by defects in enzymes involved in phenylalanine metabolism, with the consequent accumulation of phenylalanine and its secondary metabolites in body fluids and tissues. Clinical manifestations of HPA include mental retardation, and its early diagnosis with timely treatment can improve the prognosis of affected patients. Due to the genetic complexity and heterogeneity of HPA, high-throughput molecular technologies, such as next-generation sequencing (NGS), are becoming indispensable tools to fully characterize the etiology, helping clinicians to promptly identify the exact patients’ genotype and determine the appropriate treatment. In this review, after a brief overview of the key enzymes involved in phenylalanine metabolism, we represent the wide spectrum of genes and their variants associated with HPA and discuss the utility of genomic testing for improved diagnosis and clinical management of HPA.
Collapse
|
5
|
Li Y, Tan Z, Zhang Y, Zhang Z, Hu Q, Liang K, Jun Y, Ye Y, Li YC, Li C, Liao L, Xu J, Xing Z, Pan Y, Chatterjee SS, Nguyen TK, Hsiao H, Egranov SD, Putluri N, Coarfa C, Hawke DH, Gunaratne PH, Tsai KL, Han L, Hung MC, Calin GA, Namour F, Guéant JL, Muntau AC, Blau N, Sutton VR, Schiff M, Feillet F, Zhang S, Lin C, Yang L. A noncoding RNA modulator potentiates phenylalanine metabolism in mice. Science 2021; 373:662-673. [PMID: 34353949 PMCID: PMC9714245 DOI: 10.1126/science.aba4991] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 08/31/2020] [Accepted: 06/25/2021] [Indexed: 12/13/2022]
Abstract
The functional role of long noncoding RNAs (lncRNAs) in inherited metabolic disorders, including phenylketonuria (PKU), is unknown. Here, we demonstrate that the mouse lncRNA Pair and human HULC associate with phenylalanine hydroxylase (PAH). Pair-knockout mice exhibited excessive blood phenylalanine (Phe), musty odor, hypopigmentation, growth retardation, and progressive neurological symptoms including seizures, which faithfully models human PKU. HULC depletion led to reduced PAH enzymatic activities in human induced pluripotent stem cell-differentiated hepatocytes. Mechanistically, HULC modulated the enzymatic activities of PAH by facilitating PAH-substrate and PAH-cofactor interactions. To develop a therapeutic strategy for restoring liver lncRNAs, we designed GalNAc-tagged lncRNA mimics that exhibit liver enrichment. Treatment with GalNAc-HULC mimics reduced excessive Phe in Pair -/- and Pah R408W/R408W mice and improved the Phe tolerance of these mice.
Collapse
Affiliation(s)
- Yajuan Li
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Zhi Tan
- Intelligent Molecular Discovery Laboratory, Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Yaohua Zhang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Zhao Zhang
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX 77030, USA
| | - Qingsong Hu
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Ke Liang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yao Jun
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Youqiong Ye
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX 77030, USA
| | - Yi-Chuan Li
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX 77030, USA
| | - Chunlai Li
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Lan Liao
- Genetically Engineered Mouse Core, Advanced Technology Cores, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jianming Xu
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Zhen Xing
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Yinghong Pan
- Department of Biochemistry and Biology, University of Houston, Houston, TX 77030, USA
| | - Sujash S Chatterjee
- Department of Biochemistry and Biology, University of Houston, Houston, TX 77030, USA
| | - Tina K Nguyen
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Heidi Hsiao
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Sergey D Egranov
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Nagireddy Putluri
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Cristian Coarfa
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - David H Hawke
- Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Preethi H Gunaratne
- Department of Biochemistry and Biology, University of Houston, Houston, TX 77030, USA
| | - Kuang-Lei Tsai
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX 77030, USA
| | - Leng Han
- Center for Epigenetics and Disease Prevention, Institute of Biosciences and Technology, Texas A&M University, Houston, TX 77030, USA
| | - Mien-Chie Hung
- Graduate Institute of Biomedical Sciences, Research Center for Cancer Biology, and Center for Molecular Medicine, China Medical University, Taichung 404, Taiwan
- Department of Biotechnology, Asia University, Taichung 413, Taiwan
| | - George A Calin
- Department of Translational Molecular Pathology, Division of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Fares Namour
- Department of Molecular Medicine and Reference Center for Inborn Errors of Metabolism, University Hospital of Nancy, Nancy F-54000, France
- INSERM, U1256, NGERE - Nutrition, Genetics, and Environmental Risk Exposure, University of Lorraine, Nancy F-54000, France
| | - Jean-Louis Guéant
- Department of Molecular Medicine and Reference Center for Inborn Errors of Metabolism, University Hospital of Nancy, Nancy F-54000, France
- INSERM, U1256, NGERE - Nutrition, Genetics, and Environmental Risk Exposure, University of Lorraine, Nancy F-54000, France
| | - Ania C Muntau
- University Children's Hospital, University Medical Center Hamburg Eppendorf, Hamburg 20246, Germany
| | - Nenad Blau
- Division of Metabolism, University Children's Hospital Zurich, CH-8032 Zurich, Switzerland
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Manuel Schiff
- Necker Hospital, APHP, Reference Center for Inborn Error of Metabolism and Filière G2M, Pediatrics Department, University of Paris, Paris 75007, France
- Inserm UMR_S1163, Institut Imagine, Paris 75015, France
| | - François Feillet
- INSERM, U1256, NGERE - Nutrition, Genetics, and Environmental Risk Exposure, University of Lorraine, Nancy F-54000, France.
- Pediatric Department Reference Center for Inborn Errors of Metabolism Children University Hospital Nancy, Nancy F-54000, France
| | - Shuxing Zhang
- Intelligent Molecular Discovery Laboratory, Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA.
- The Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Chunru Lin
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
- The Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Liuqing Yang
- Department of Molecular and Cellular Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
- The Graduate School of Biomedical Sciences, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Center for RNA Interference and Non-Coding RNAs, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| |
Collapse
|
6
|
Lopez A, Havranek B, Papadantonakis GA, Islam SM. In silico screening and molecular dynamics simulation of deleterious PAH mutations responsible for phenylketonuria genetic disorder. Proteins 2021; 89:683-696. [PMID: 33491267 DOI: 10.1002/prot.26051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 01/08/2021] [Accepted: 01/21/2021] [Indexed: 12/23/2022]
Abstract
Phenylketonuria (PKU) is a genetic disorder that if left untreated can lead to behavioral problems, epilepsy, and even mental retardation. PKU results from mutations within the phenylalanine-4-hydroxylase (PAH) gene that encodes for the PAH protein. The study of all PAH causing mutations is improbable using experimental techniques. In this study, a collection of in silico resources, sorting intolerant from tolerant, Polyphen-2, PhD-SNP, and MutPred were used to identify possible pathogenetic and deleterious PAH non-synonymous single nucleotide polymorphisms (nsSNPs). We identified two variants of PAH, I65N and L311P, to be the most deleterious and disease causing nsSNPs. Molecular dynamics (MD) simulations were carried out to characterize these point mutations on the atomic level. MD simulations revealed increased flexibility and a decrease in the hydrogen bond network for both mutants compared to the native protein. Free energy calculations using the MM/GBSA approach found that BH4 , a drug-based therapy for PKU patients, had a higher binding affinity for I65N and L311P mutants compared to the wildtype protein. We also identify important residues in the BH4 binding pocket that may be of interest for the rational drug design of other PAH drug-based therapies. Lastly, free energy calculations also determined that the I65N mutation may impair the dimerization of the N-terminal regulatory domain of PAH.
Collapse
Affiliation(s)
- Andrea Lopez
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois, USA
| | - Brandon Havranek
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois, USA
| | | | - Shahidul M Islam
- Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois, USA
| |
Collapse
|
7
|
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
|
8
|
Chen S, Zhu M, Hao Y, Feng J, Zhang Y. Effect of Delayed Diagnosis of Phenylketonuria With Imaging Findings of Bilateral Diffuse Symmetric White Matter Lesions: A Case Report and Literature Review. Front Neurol 2019; 10:1040. [PMID: 31636599 PMCID: PMC6788382 DOI: 10.3389/fneur.2019.01040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 09/13/2019] [Indexed: 11/17/2022] Open
Abstract
Phenylketonuria is a hereditary metabolic disorder due to the deficiency of tetrahydrobiopterin or phenylalanine hydroxylase. Delayed diagnoses of it manifest a progressive irreversible neurological impairment in the early years of the disease. Guthrie test and tandem mass spectrometry aided in early detection and intervention of phenylketonuria, which significantly decreased the disability of patients as well as reducing the need for diagnosis in adults. This is a case report of a 60-year-old Asian man, characterized by severe visual-spatial disorders and bilateral diffuse symmetric white matter lesions on magnetic resonance imaging, who was diagnosed as phenylketonuria with his congenital mental retardation sibling. Heterozygous mutations exist in gene encoding PAH c.1068C>A and c.740G>T. During the diagnosis, we looked up at other late-onset genetic diseases considered to occur rarely but gradually revealed similar clinical manifestations and significant white matter lesions gaining importance in guiding to correct diagnosis and treatment. We made a comprehensive review of phenylketonuria and other inherited diseases with major prevalence in adulthood with prominent white matter involvement. Our study aims to help neurologists to improve recognition of metabolism-related leukoencephalopathies without neglect of the role of congenital genetic factors.
Collapse
|
9
|
Scheller R, Stein A, Nielsen SV, Marin FI, Gerdes AM, Di Marco M, Papaleo E, Lindorff-Larsen K, Hartmann-Petersen R. Toward mechanistic models for genotype-phenotype correlations in phenylketonuria using protein stability calculations. Hum Mutat 2019; 40:444-457. [PMID: 30648773 DOI: 10.1002/humu.23707] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 12/18/2018] [Accepted: 01/13/2019] [Indexed: 01/22/2023]
Abstract
Phenylketonuria (PKU) is a genetic disorder caused by variants in the gene encoding phenylalanine hydroxylase (PAH), resulting in accumulation of phenylalanine to neurotoxic levels. Here, we analyzed the cellular stability, localization, and interaction with wild-type PAH of 20 selected PKU-linked PAH protein missense variants. Several were present at reduced levels in human cells, and the levels increased in the presence of a proteasome inhibitor, indicating that proteins are proteasome targets. We found that all the tested PAH variants retained their ability to associate with wild-type PAH, and none formed aggregates, suggesting that they are only mildly destabilized in structure. In all cases, PAH variants were stabilized by the cofactor tetrahydrobiopterin (BH4 ), a molecule known to alleviate symptoms in certain PKU patients. Biophysical calculations on all possible single-site missense variants using the full-length structure of PAH revealed a strong correlation between the predicted protein stability and the observed stability in cells. This observation rationalizes previously observed correlations between predicted loss of protein destabilization and disease severity, a correlation that we also observed using new calculations. We thus propose that many disease-linked PAH variants are structurally destabilized, which in turn leads to proteasomal degradation and insufficient amounts of cellular PAH protein.
Collapse
Affiliation(s)
- Rasmus Scheller
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Amelie Stein
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Sofie V Nielsen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Frederikke I Marin
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Anne-Marie Gerdes
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
| | - Miriam Di Marco
- Computational Biology Laboratory, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Elena Papaleo
- Computational Biology Laboratory, Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Kresten Lindorff-Larsen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Hartmann-Petersen
- The Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
10
|
Shirzadeh T, Saeidian AH, Bagherian H, Salehpour S, Setoodeh A, Alaei MR, Youssefian L, Samavat A, Touati A, Fallah MS, Vahidnezhad H, Karimipoor M, Azadmehr S, Raeisi M, Bandehi Sarhadi A, Zafarghandi Motlagh F, Jamali M, Zeinali Z, Abiri M, Zeinali S. Molecular genetics of a cohort of 635 cases of phenylketonuria in a consanguineous population. J Inherit Metab Dis 2018; 41:1159-1167. [PMID: 30159852 DOI: 10.1007/s10545-018-0228-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 06/09/2018] [Accepted: 06/26/2018] [Indexed: 11/28/2022]
Abstract
Phenylketonuria (PKU) is an inborn error of amino acid metabolism caused by mutations in the phenylalanine hydroxylase (PAH) gene, characterized by intellectual deficit and neuropsychiatric complications in untreated patients with estimated frequency of about one in 10,000 to 15,000 live births. PAH deficiency can be detected by neonatal screening in nearly all cases with hyperphenylalaninemia on a heel prick blood spot. Molecular testing of the PAH gene can then be performed in affected family members. Herein, we report molecular study of 635 patients genetically diagnosed with PKU from all ethnicities in Iran. The disease-causing mutations were found in 611 (96.22%) of cases. To the best of our knowledge, this is the most comprehensive molecular genetics study of PKU in Iran, identifying 100 distinct mutations in the PAH gene, including 15 previously unreported mutations. Interestingly, we found unique cases of PKU with uniparental disomy, germline mosaicism, and coinheritance with another Mendelian single-gene disorder that provides new insights for improving the genetic counseling, prenatal diagnosis (PND), and/or pre-implantation genetic diagnosis (PGD) for the inborn error of metabolism group of disorders.
Collapse
Affiliation(s)
- Tina Shirzadeh
- Kawsar Human Genetics Research Center, 41 Majlesi St., Vali Asr St., Tehran, 1595645513, Iran
| | - Amir Hossein Saeidian
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
- Genetic, Genomics and Cancer Biology PhD Program, Thomas Jefferson University, Philadelphia, PA, USA
| | - Hamideh Bagherian
- Kawsar Human Genetics Research Center, 41 Majlesi St., Vali Asr St., Tehran, 1595645513, Iran
| | - Shadab Salehpour
- Department of Pediatric Endocrinology and Metabolism, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Genomic Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Aria Setoodeh
- Growth and Development Research Center, Tehran University of Medical Sciences, Tehran, Iran
- Department of Pediatrics, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza Alaei
- Department of Pediatric Endocrinology and Metabolism, Mofid Children's Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Leila Youssefian
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
- Genetic, Genomics and Cancer Biology PhD Program, Thomas Jefferson University, Philadelphia, PA, USA
- Department of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Ashraf Samavat
- Genetics Office, CDC, Ministry of Health of Iran, Tehran, Iran
| | - Andrew Touati
- Drexel University College of Medicine, Philadelphia, PA, USA
| | - Mohammad-Sadegh Fallah
- Kawsar Human Genetics Research Center, 41 Majlesi St., Vali Asr St., Tehran, 1595645513, Iran
| | - Hassan Vahidnezhad
- Department of Dermatology and Cutaneous Biology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
- Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Morteza Karimipoor
- Department of Molecular Medicine, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran
| | - Sarah Azadmehr
- Kawsar Human Genetics Research Center, 41 Majlesi St., Vali Asr St., Tehran, 1595645513, Iran
| | - Marzieh Raeisi
- Research Institute for Endocrine Science, Shahid Beheshti University of Medical Sciences, Tehran, Iran
- Department of cellular and molecular biology, Islamic Azad University North Tehran branch, Tehran, Iran
| | - Ameneh Bandehi Sarhadi
- Kawsar Human Genetics Research Center, 41 Majlesi St., Vali Asr St., Tehran, 1595645513, Iran
| | | | - Mojdeh Jamali
- Kawsar Human Genetics Research Center, 41 Majlesi St., Vali Asr St., Tehran, 1595645513, Iran
| | - Zahra Zeinali
- Kawsar Human Genetics Research Center, 41 Majlesi St., Vali Asr St., Tehran, 1595645513, Iran
| | - Maryam Abiri
- Department of Medical Genetics, School of Medicine, Iran University of Medical Sciences, Tehran, Iran.
| | - Sirous Zeinali
- Kawsar Human Genetics Research Center, 41 Majlesi St., Vali Asr St., Tehran, 1595645513, Iran.
- Department of Molecular Medicine, Biotech Research Center, Pasteur Institute of Iran, Tehran, Iran.
| |
Collapse
|
11
|
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
|
12
|
Three novel variants (p.Glu178Lys, p.Val245Met, p.Ser250Phe) of the phenylalanine hydroxylase (PAH) gene impair protein expression and function in vitro. Gene 2018; 668:135-139. [PMID: 29653233 DOI: 10.1016/j.gene.2018.03.078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 03/10/2018] [Accepted: 03/26/2018] [Indexed: 11/21/2022]
Abstract
Phenylketonuria (PKU) is the most common inherited metabolic disease, an autosomal recessive disorder affecting >10,000 newborns each year globally. It can be caused by over 1000 different naturally occurring mutations in the phenylalanine hydroxylase (PAH) gene. We analyzed three novel naturally occurring PAH gene variants: p.Glu178Lys (c.532G>A), p.Val245Met (c.733G>A) and p.Ser250Phe (c.749C>T). The mutant effect on the PAH enzyme structure and function was predicted by bioinformatics software. Vectors expressing the corresponding PAH variants were generated for expression in E. coli and in HEK293T cells. The RNA expression of the three PAH variants was measured by quantitative reverse transcription polymerase chain reaction (RT-qPCR). The mutant PAH protein levels were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), western blot and enzyme-linked immunosorbent assay (ELISA). All three variants were predicted to be pathogenic by bioinformatics analysis. The transcription of the three PAH variants was similar to the wild type PAH gene in HEK293T cells. In contrast, the levels of mutant PAH proteins decreased significantly compared to the wild type control, in both E. coli and HEK293T cells. Our results indicate that the three novel PAH gene variants (p.Glu178Lys, p.Val245Met, p.Ser250Phe) impair PAH protein expression and function in prokaryotic and eukaryotic cells.
Collapse
|
13
|
Li N, He C, Li J, Tao J, Liu Z, Zhang C, Yuan Y, Jiang H, Zhu J, Deng Y, Guo Y, Li Q, Yu P, Wang Y. Analysis of the genotype-phenotype correlation in patients with phenylketonuria in mainland China. Sci Rep 2018; 8:11251. [PMID: 30050108 PMCID: PMC6062512 DOI: 10.1038/s41598-018-29640-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 07/13/2018] [Indexed: 11/22/2022] Open
Abstract
Mutations in the gene encoding phenylalanine hydroxylase (PAH) are associated with various degrees of phenylketonuria (PKU). The aim of our study was to define the genotype-phenotype correlations of mutations in the PAH gene that cause phenylketonuria (PKU) among the Chinese mainland population. Mutations in the PAH gene were analysed by next-generation sequencing, and a genotype-phenotype correlation analysis was performed in 1079 patients. Fifteen “null + null” genotypes, including four homoallelic and eleven heteroallelic genotypes, were clearly associated with classic PKU. Five functionally hemizygous (p.E280K, p.R252Q, p.E56D, p.S310F and p.T372R) and four compound heterozygous (p.T278I/p.S359L, p.R408W/p.R243Q, p.F161S/p.R243Q and p.F161S/p.R413P) genotypes were clearly associated with classic PKU. Ten functionally hemizygous genotypes, p.G257V, p.R158W, p.L255S, p.G247V, p.F161S, p.R158Q, p.V388M, p.I65T, p.I324N and p.R400K, were frequently associated with classic PKU. Three functionally hemizygous genotypes, p.P147L, p.I95del and p.F331S, and four compound heterozygous genotypes, p.G257V/p.R408Q, p.A434D/p.R413P, p.R243Q/p.A47E and p.R241C/p.G239D, were consistently correlated with mild PKU. Three functionally hemizygous genotypes, p.H107R, p.Q419R and p.F392I, and nine compound heterozygous genotypes (p.G312V/p.R241C, p.R243Q/p.V230I, p.R243Q/p.A403V, p.R243Q/p.Q419R, p.R243Q/p.R53H, p.R243Q/p.H107R, p.R241C/p.R408Q, p.R241C/p.H220P and p.R53H/p.R400K) were consistent with mild hyperphenylalaninaemia (MHP). Our study provides further support for the hypothesis that the PAH genotype is the main factor that determines the phenotype of PKU.
Collapse
Affiliation(s)
- Nana Li
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Chunhua He
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Jing Li
- Laboratory of Translational Medicine, Chinese PLA General Hospital, Beijing, China
| | - Jing Tao
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Zhen Liu
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Chunyan Zhang
- Laboratory of Translational Medicine, Chinese PLA General Hospital, Beijing, China
| | - Yuan Yuan
- Tianjin Medical Laboratory, BGI-Tianjin, BGI-Shenzhen, Tianjin, 300308, China
| | - Hui Jiang
- BGI-Shenzhen, Shenzhen, 518103, China.,China National GeneBank, BGI-Shenzhen, Shenzhen, 518120, China
| | - Jun Zhu
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Ying Deng
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Yixiong Guo
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China.,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Qintong Li
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Ping Yu
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China. .,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China.
| | - Yanping Wang
- National Center for Birth Defect Monitoring, West China Second University Hospital, Sichuan University, Chengdu, China. .,Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China.
| |
Collapse
|
14
|
Taipale M. Disruption of protein function by pathogenic mutations: common and uncommon mechanisms 1. Biochem Cell Biol 2018; 97:46-57. [PMID: 29693415 DOI: 10.1139/bcb-2018-0007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mutations in protein-coding regions underlie almost all Mendelian disorders, drive tumorigenesis, and contribute to susceptibility to common diseases. Despite the great diversity of diseases that are caused by coding mutations, the cellular processes that affect, and are affected by, pathogenic variants at the molecular level are fundamentally conserved. Experimental and computational approaches have revealed that a substantial fraction of disease mutations are not simple loss-of-function alleles. Rather, these pathogenic variants disrupt protein function in more subtle ways by tuning protein folding pathways, altering subcellular trafficking, interrupting signaling cascades, and rewiring highly connected interaction networks. Focusing mainly on Mendelian disorders, this review discusses the common mechanisms by which deleterious mutations disrupt protein function and how these disruptions can be exploited in the development of novel therapies.
Collapse
Affiliation(s)
- Mikko Taipale
- a Donnelly Centre, Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 3E1, Canada.,b Molecular Architecture of Life Program, Canadian Institute for Advanced Research, Toronto, ON M5S 1M1, Canada
| |
Collapse
|
15
|
Hamilton V, Santa María L, Fuenzalida K, Morales P, Desviat LR, Ugarte M, Pérez B, Cabello JF, Cornejo V. Characterization of Phenyalanine Hydroxylase Gene Mutations in Chilean PKU Patients. JIMD Rep 2017; 42:71-77. [PMID: 29288420 PMCID: PMC6226402 DOI: 10.1007/8904_2017_85] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 12/01/2017] [Accepted: 12/07/2017] [Indexed: 02/10/2023] Open
Abstract
UNLABELLED Phenylketonuria (PKU, OMIM 261600) is an autosomal recessive disease, caused by mutations in the Phenylalanine Hydroxylase (PAH) gene situated in chromosome 12q22-q24.2. This gene has 13 exons. To date, 991 mutations have been described. The genotype is one of the main factors that determine the phenotype of this disease. OBJECTIVE Characterize PKU genotype and phenotype seen in Chilean PKU patients. METHODS We studied the PAH gene by restriction fragment length polymorphism (RFLP) and/or sequencing techniques to identify pathogenic mutations in 71 PKU subjects. We classified the phenotype according to Guldberg predicted value. RESULTS We identified 26 different mutations in 134 of the 142 alleles studied (94.4%), 88.7% of the subjects had biallelic pathogenic mutations while 11.3% had only one pathogenic mutation identified. Compound heterozygous represented 85.9% of the cases. Exon 7 included the majority of mutations (26.9%) and 50% of mutations were missense. The most frequent mutations were c.1066-11G > A, c.442-?_509+?del and p.Val388Met. The majority of subjects (52.3%) had the classic phenotype. CONCLUSIONS The most frequent mutations in our Chilean PKU population were p.Val388Met, c.442?_509+?del and c.1066-11G > A. It is possible to predict phenotype by detecting the genotype, and use this information to determine disease prognosis and adjust patient's medical and nutritional management accordingly.
Collapse
Affiliation(s)
- V Hamilton
- Instituto de Nutrición y Tecnología de los Alimentos, Dr. Fernando Monckeberg Barros, Universidad de Chile, Santiago, Chile.
| | - L Santa María
- Instituto de Nutrición y Tecnología de los Alimentos, Dr. Fernando Monckeberg Barros, Universidad de Chile, Santiago, Chile
| | - K Fuenzalida
- Instituto de Nutrición y Tecnología de los Alimentos, Dr. Fernando Monckeberg Barros, Universidad de Chile, Santiago, Chile
| | - P Morales
- Instituto de Nutrición y Tecnología de los Alimentos, Dr. Fernando Monckeberg Barros, Universidad de Chile, Santiago, Chile
| | - L R Desviat
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), CIBERER Universidad Autónoma de Madrid, Madrid, Spain
| | - M Ugarte
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), CIBERER Universidad Autónoma de Madrid, Madrid, Spain
| | - B Pérez
- Centro de Diagnóstico de Enfermedades Moleculares (CEDEM), CIBERER Universidad Autónoma de Madrid, Madrid, Spain
| | - J F Cabello
- Instituto de Nutrición y Tecnología de los Alimentos, Dr. Fernando Monckeberg Barros, Universidad de Chile, Santiago, Chile
| | - V Cornejo
- Instituto de Nutrición y Tecnología de los Alimentos, Dr. Fernando Monckeberg Barros, Universidad de Chile, Santiago, Chile
| |
Collapse
|
16
|
Yang H, Al-Hertani W, Cyr D, Laframboise R, Parizeault G, Wang SP, Rossignol F, Berthier MT, Giguère Y, Waters PJ, Mitchell GA. Hypersuccinylacetonaemia and normal liver function in maleylacetoacetate isomerase deficiency. J Med Genet 2016; 54:241-247. [PMID: 27876694 DOI: 10.1136/jmedgenet-2016-104289] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/29/2016] [Accepted: 11/01/2016] [Indexed: 11/04/2022]
Abstract
BACKGROUND A high level of succinylacetone (SA) in blood is a sensitive, specific newborn screening marker for hepatorenal tyrosinemia type 1 (HT1, MIM 276700) caused by deficiency of fumarylacetoacetate hydrolase (FAH). Newborns with HT1 are usually clinically asymptomatic but show liver dysfunction with coagulation abnormalities (prolonged prothrombin time and/or high international normalised ratio). Early treatment with nitisinone (NTBC) plus dietary restriction of tyrosine and phenylalanine prevents the complications of severe liver disease and neurological crises. METHODS AND RESULTS Six newborns referred for hypersuccinylacetonaemia but who had normal coagulation testing on initial evaluation had sequence variants in the GSTZ1 gene, encoding maleylacetoacetate isomerase (MAAI), the enzyme preceding FAH in tyrosine degradation. Initial plasma SA levels ranged from 233 to 1282 nmol/L, greater than normal (<24 nmol/L) but less than the initial values of patients with HT1 (16 944-74 377 nmol/L, n=15). Four individuals were homozygous for c.449C>T (p.Ala150Val). One was compound heterozygous for c.259C>T (p.Arg87Ter) and an intronic sequence variant. In one, a single heterozygous GSTZ1 sequence variant was identified, c.295G>A (p.Val99Met). Bacterial expression of p.Ala150Val and p.Val99Met revealed low MAAI activity. The six individuals with mild hypersuccinylacetonaemia (MHSA) were not treated with diet or nitisinone. Their clinical course has been normal for up to 13 years. CONCLUSIONS MHSA can be caused by sequence variants in GSTZ1. Such individuals have thus far remained asymptomatic despite receiving no specific treatment.
Collapse
Affiliation(s)
- Hao Yang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada.,College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, China
| | - Walla Al-Hertani
- Departments of Medical Genetics and Paediatrics, Cumming School of Medicine, University of Calgary and Alberta Children's Hospital, Calgary, Alberta, Canada.,Department of Medical Genetics, Centre universitaire de Santé McGill (CUSM), Québec, Canada
| | - Denis Cyr
- Service de Génétique médicale, Département de Pédiatrie, Centre hospitalier universitaire de Sherbrooke (CHUS), Sherbrooke, Québec, Canada
| | - Rachel Laframboise
- Service de Génétique médicale, Département de Pédiatrie, CHU de Québec-Centre hospitalier de l'Université Laval (CHUL), Québec City, Québec, Canada
| | - Guy Parizeault
- Département de Pédiatrie, Centre Hospitalier de la Sagamie, Sagamie, Québec, Canada
| | - Shu Pei Wang
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada
| | - Francis Rossignol
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada
| | - Marie-Thérèse Berthier
- Programme québécois de Dépistage Néonatal Sanguin, CHU de Québec-Université Laval, Québec City, Québec, Canada
| | - Yves Giguère
- Programme québécois de Dépistage Néonatal Sanguin, CHU de Québec-Université Laval, Québec City, Québec, Canada
| | - Paula J Waters
- Service de Génétique médicale, Département de Pédiatrie, Centre hospitalier universitaire de Sherbrooke (CHUS), Sherbrooke, Québec, Canada
| | - Grant A Mitchell
- Division of Medical Genetics, Department of Pediatrics, CHU Sainte-Justine and Université de Montréal, Montréal, Québec, Canada
| | | |
Collapse
|
17
|
Abstract
Detection of individuals with phenylketonuria (PKU), an autosomal recessively inherited disorder in phenylalanine degradation, is straightforward and efficient due to newborn screening programs. A recent introduction of the pharmacological treatment option emerged rapid development of molecular testing. However, variants responsible for PKU do not all suppress enzyme activity to the same extent. A spectrum of over 850 variants, gives rise to a continuum of hyperphenylalaninemia from very mild, requiring no intervention, to severe classical PKU, requiring urgent intervention. Locus-specific and genotypes database are today an invaluable resource of information for more efficient classification and management of patients. The high-tech molecular methods allow patients' genotype to be obtained in a few days, especially if each laboratory develops a panel for the most frequent variants in the corresponding population.
Collapse
Affiliation(s)
- Nenad Blau
- Division of Inborn Metabolic Diseases, University Children's Hospital, Im Neuenheimer Feld 430, 69120 Heidelberg, Germany
| | | | | |
Collapse
|
18
|
Abstract
Phenylketonuria (PKU) is an inborn error of metabolism of the amino acid phenylalanine. It is an autosomal recessive disorder with a rate of incidence of 1 in 10,000 in Caucasian populations. Mutations in the phenylalanine hydroxylase (PAH) gene are the major cause of PKU, due to the loss of the catalytic activity of the enzyme product PAH. Newborn screening for PKU allows early intervention, avoiding irreparable neurological damage and intellectual disability that would arise from untreated PKU. The current primary treatment of PKU is the limitation of dietary protein intake, which in the long term may be associated with poor compliance in some cases and other health problems due to malnutrition. The only alternative therapy currently approved is the supplementation of BH4, the requisite co-factor of PAH, in the orally-available form of sapropterin dihydrochloride. This treatment is not universally available, and is only effective for a proportion (estimated 30%) of PKU patients. Research into novel therapies for PKU has taken many different approaches to address the lack of PAH activity at the core of this disorder: enzyme replacement via virus-mediated gene transfer, transplantation of donor liver and recombinant PAH protein, enzyme substitution using phenylalanine ammonia lyase (PAL) to provide an alternative pathway for the metabolism of phenylalanine, and restoration of native PAH activity using chemical chaperones and nonsense read-through agents. It is hoped that continuing efforts into these studies will translate into a significant improvement in the physical outcome, as well as quality of life, for patients with PKU.
Collapse
Affiliation(s)
- Gladys Ho
- 1 Genetic Metabolic Disorders Research Unit; 2 Disciplines of Paediatrics and Child Health and 3 Genetic Medicine, University of Sydney, Sydney, NSW, Australia ; 4 Genetic Metabolic Disorders Service, Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, NSW, Australia
| | - John Christodoulou
- 1 Genetic Metabolic Disorders Research Unit; 2 Disciplines of Paediatrics and Child Health and 3 Genetic Medicine, University of Sydney, Sydney, NSW, Australia ; 4 Genetic Metabolic Disorders Service, Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, NSW, Australia
| |
Collapse
|
19
|
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]
|
20
|
Heintz C, Cotton RGH, Blau N. Tetrahydrobiopterin, its mode of action on phenylalanine hydroxylase, and importance of genotypes for pharmacological therapy of phenylketonuria. Hum Mutat 2013; 34:927-36. [PMID: 23559577 DOI: 10.1002/humu.22320] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Revised: 03/20/2013] [Accepted: 03/20/2013] [Indexed: 11/11/2022]
Abstract
In about 20%-30% of phenylketonuria (PKU) patients (all phenotypes of PAH deficiency), Phe levels may be controlled through phenylalanine hydroxylase cofactor tetrahydrobiopterin therapy. These patients can be diagnosed by an oral tetrahydrobiopterin challenge and are characterized by mutations coding for proteins with substantial residual PAH activity. They can be treated with a commercially available synthetic form of tetrahydrobiopterin, either as a monotherapy or as adjunct to the diet. This review article summarizes molecular and metabolic bases of PKU and the importance of the tetrahydrobiopterin loading test used for PKU patients. On the basis of in vitro residual PAH activity, more than 1,200 genotypes from patients challenged with tetrahydrobiopterin were categorized as predictive for tetrahydrobiopterin responsiveness or non-responsiveness and correlated with the loading test, phenotype, and residual in vitro PAH activity. The coexpression of two distinct PAH mutant alleles revealed possible dominance effects (positive or negative) by one of the mutations on residual activity as result of interallelic complementation. The treatment of the transfected cells with tetrahydrobiopterin showed an increase in residual PAH activity with several mutations coexpressed.
Collapse
|
21
|
Sarkissian CN, Ying M, Scherer T, Thöny B, Martinez A. The mechanism of BH4 -responsive hyperphenylalaninemia--as it occurs in the ENU1/2 genetic mouse model. Hum Mutat 2012; 33:1464-73. [PMID: 22644647 DOI: 10.1002/humu.22128] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Accepted: 05/15/2012] [Indexed: 01/07/2023]
Abstract
The Pah(enu1/enu2) (ENU1/2) mouse is a heteroallelic orthologous model displaying blood phenylalanine (Phe) concentrations characteristic of mild hyperphenylalaninemia. ENU1/2 mice also have reduced liver phenylalanine hydroxylase (PAH) protein content (∼20% normal) and activity (∼2.5% normal). The mutant PAH protein is highly ubiquitinated, which is likely associated with its increased misfolding and instability. The administration of a single subcutaneous injection of l-Phe (1.1 mg l-Phe/g body weight) leads to an approximately twofold to threefold increase of blood Phe and phenylalanine/tyrosine (Phe/Tyr) ratio, and a 1.6-fold increase of both nonubiquitinated PAH protein content and PAH activity. It also results in elevated concentrations of liver 6R-l-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)), potentially through the influence of Phe on GTP cyclohydrolase I and its feedback regulatory protein. The increased BH(4) content seems to stabilize PAH. Supplementing ENU1/2 mice with BH(4) (50 mg/kg/day for 10 days) reduces the blood Phe/Tyr ratio within the mild hyperphenylalaninemic range; however, PAH content and activity were not elevated. It therefore appears that BH(4) supplementation of ENU1/2 mice increases Phe hydroxylation levels through a kinetic rather than a chaperone stabilizing effect. By boosting blood Phe concentrations, and by BH(4) supplementation, we have revealed novel insights into the processing and regulation of the ENU1/2-mutant PAH.
Collapse
Affiliation(s)
- Christineh N Sarkissian
- Department of Human Genetics, McGill University-Montreal Children's Hospital Research Institute, Montreal, Quebec, Canada
| | | | | | | | | |
Collapse
|
22
|
Groselj U, Tansek MZ, Kovac J, Hovnik T, Podkrajsek KT, Battelino T. Five novel mutations and two large deletions in a population analysis of the phenylalanine hydroxylase gene. Mol Genet Metab 2012; 106:142-8. [PMID: 22513348 DOI: 10.1016/j.ymgme.2012.03.015] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2012] [Revised: 03/22/2012] [Accepted: 03/22/2012] [Indexed: 11/30/2022]
Abstract
Mutational spectrum of the phenylalanine hydroxylase (PAH) deficiency was investigated in 107 families (90% of the Slovene PKU population). The entire coding region of the PAH gene was analyzed with dHPLC to select the samples where subsequently the automated sequencing analysis was performed. MLPA analysis was performed to identify large deletions, which were later confirmed with long-range PCR. Correlations with patients' phenotypes and genotype-based predictions of BH(4)-responsiveness were assessed. Altogether, disease-causing mutations were identified on 209 alleles (detection rate 97.7%). A spectrum of 36 different disease-causing mutations was identified: 20 missense mutations (80% of the alleles), eight splicing mutations (13% of the alleles), one nonsense mutation (0.5% of the alleles), four small deletions with frame shift (6% of the alleles), one small insertion with frame shift (0.5% of the alleles), and two large deletions (2% of the alleles). The most frequent mutation was p.R408W in exon 12, representing 29% of the alleles, which is in concordance with other neighboring and/or Slavic PKU populations. Other common mutations were: p.R158Q, p.A403V, p.P281L and p.E390G, accounting for 9%, 7%, 7% and 7% of the alleles respectively. Five novel mutations were detected: c.43_44insAG, c.56_59+1delACAGG, p.V45A, p.L62P and p.R157S. Large deletion of exon 5 (EX5del955) was found in three patients and a deletion of exon 3 (EX3del4765) in one patient. A spectrum of 64 different genotypes was found, seven of them accounting for over than a third of all families. Among thirteen families with homozygous mutation (13% of the PKU population), 10 had p.R408W, two had p.R158Q and one had p.E390G. Among 107 families, 58 were classified as classic PKU (54.2%), 28 as mild PKU (25.9%) and 21 as MHP (19.6%). Twenty-six different genotypes (40.6%) were predicted to be BH(4)-responsive, represented by 38 different families (35.5%).
Collapse
Affiliation(s)
- Urh Groselj
- Department of Pediatric Endocrinology, Diabetes and Metabolic Diseases, University Children's Hospital, UMC Ljubljana, Ljubljana, Slovenia
| | | | | | | | | | | |
Collapse
|
23
|
Underhaug J, Aubi O, Martinez A. Phenylalanine hydroxylase misfolding and pharmacological chaperones. Curr Top Med Chem 2012; 12:2534-45. [PMID: 23339306 PMCID: PMC3664513 DOI: 10.2174/1568026611212220008] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 08/28/2012] [Accepted: 08/29/2012] [Indexed: 12/15/2022]
Abstract
Phenylketonuria (PKU) is a loss-of-function inborn error of metabolism. As many other inherited diseases the main pathologic mechanism in PKU is an enhanced tendency of the mutant phenylalanine hydroxylase (PAH) to misfold and undergo ubiquitin-dependent degradation. Recent alternative approaches with therapeutic potential for PKU aim at correcting the PAH misfolding, and in this respect pharmacological chaperones are the focus of increasing interest. These compounds, which often resemble the natural ligands and show mild competitive inhibition, can rescue the misfolded proteins by stimulating their renaturation in vivo. For PKU, a few studies have proven the stabilization of PKU-mutants in vitro, in cells, and in mice by pharmacological chaperones, which have been found either by using the tetrahydrobiopterin (BH(4)) cofactor as query structure for shape-focused virtual screening or by high-throughput screening of small compound libraries. Both approaches have revealed a number of compounds, most of which bind at the iron-binding site, competitively with respect to BH(4). Furthermore, PAH shares a number of ligands, such as BH(4), amino acid substrates and inhibitors, with the other aromatic amino acid hydroxylases: the neuronal/neuroendocrine enzymes tyrosine hydroxylase (TH) and the tryptophan hydroxylases (TPHs). Recent results indicate that the PAH-targeted pharmacological chaperones should also be tested on TH and the TPHs, and eventually be derivatized to avoid unwanted interactions with these other enzymes. After derivatization and validation in animal models, the PAH-chaperoning compounds represent novel possibilities in the treatment of PKU.
Collapse
Affiliation(s)
| | | | - Aurora Martinez
- Department of Biomedicine, and K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway
| |
Collapse
|
24
|
Ben-Rebeh I, Hertecant JL, Al-Jasmi FA, Aburawi HE, Al-Yahyaee SA, Al-Gazali L, Ali BR. Identification of mutations underlying 20 inborn errors of metabolism in the United Arab Emirates population. Genet Test Mol Biomarkers 2011; 16:366-71. [PMID: 22106832 DOI: 10.1089/gtmb.2011.0175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Inborn errors of metabolism (IEM) are frequently encountered by physicians in the United Arab Emirates (UAE). However, the mutations underlying a large number of these disorders have not yet been determined. Therefore, the objective of this study was to identify the mutations underlying a number of IEM disorders among UAE residents from both national and expatriate families. A case series of patients from 34 families attending the metabolic clinic at Tawam Hospital were clinically evaluated, and molecular testing was carried out to determine their causative mutations. The mutation analysis was carried out at molecular genetics diagnostic laboratories. Thirty-eight mutations have been identified as responsible for twenty IEM disorders, including in the metabolism of amino acids, lipids, steroids, metal transport and mitochondrial energy metabolism, and lysosomal storage disorders. Nine of the identified mutations are novel, including two missense mutations, three premature stop codons and four splice site mutations. Mutation analysis of IEM disorders in the UAE population has an important impact on molecular diagnosis and genetic counseling for families affected by these disorders.
Collapse
Affiliation(s)
- Imen Ben-Rebeh
- Department of Pathology, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | | | | | | | | | | | | |
Collapse
|
25
|
Blau N, Hennermann JB, Langenbeck U, Lichter-Konecki U. Diagnosis, classification, and genetics of phenylketonuria and tetrahydrobiopterin (BH4) deficiencies. Mol Genet Metab 2011; 104 Suppl:S2-9. [PMID: 21937252 DOI: 10.1016/j.ymgme.2011.08.017] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2011] [Revised: 08/17/2011] [Accepted: 08/17/2011] [Indexed: 11/29/2022]
Abstract
This article summarizes the present knowledge, recent developments, and common pitfalls in the diagnosis, classification, and genetics of hyperphenylalaninemia, including tetrahydrobiopterin (BH4) deficiency. It is a product of the recent workshop organized by the European Phenylketonuria Group in March 2011 in Lisbon, Portugal. Results of the workshop demonstrate that following newborn screening for phenylketonuria (PKU), using tandem mass-spectrometry, every newborn with even slightly elevated blood phenylalanine (Phe) levels needs to be screened for BH4 deficiency. Dried blood spots are the best sample for the simultaneous measurement of amino acids (phenylalanine and tyrosine), pterins (neopterin and biopterin), and dihydropteridine reductase activity from a single specimen. Following diagnosis, the patient's phenotype and individually tailored treatment should be established as soon as possible. Not only blood Phe levels, but also daily tolerance for dietary Phe and potential responsiveness to BH4 are part of the investigations. Efficiency testing with synthetic BH4 (sapropterin dihydrochloride) over several weeks should follow the initial 24-48-hour screening test with 20mg/kg/day BH4. The specific genotype, i.e. the combination of both PAH alleles of the patient, helps or facilitates to determine both the biochemical phenotype (severity of PKU) and the responsiveness to BH4. The rate of Phe metabolic disposal after Phe challenge may be an additional useful tool in the interpretation of phenotype-genotype correlation.
Collapse
Affiliation(s)
- Nenad Blau
- University Children's Hospital, Zürich, Switzerland.
| | | | | | | |
Collapse
|
26
|
Rivera I, Mendes D, Afonso Â, Barroso M, Ramos R, Janeiro P, Oliveira A, Gaspar A, Tavares de Almeida I. Phenylalanine hydroxylase deficiency: molecular epidemiology and predictable BH4-responsiveness in South Portugal PKU patients. Mol Genet Metab 2011; 104 Suppl:S86-92. [PMID: 21871829 DOI: 10.1016/j.ymgme.2011.07.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 07/27/2011] [Accepted: 07/28/2011] [Indexed: 11/23/2022]
Abstract
Hyperphenylalaninemia (HPA, OMIM #261600), which includes phenylketonuria (PKU), is caused by mutations in the gene encoding phenylalanine hydroxylase (PAH), being already described more than 600 different mutations. Genotype-phenotype correlation is a useful tool to predict the metabolic phenotype, to establish the better tailored diet and, more recently, to assess the potential responsiveness to BH(4) therapy, a current theme on PKU field. The aim of this study was the molecular analysis of the PAH gene, evaluation of genotype-phenotype relationships and prediction of BH(4)-responsiveness in the HPA population living in South Portugal. We performed the molecular characterization of 83 HPA patients using genomic DNA extracted from peripheral blood samples or Guthrie cards. PAH mutations were scanned by PCR amplification of exons and related intronic boundaries, followed by direct sequence analysis. Intragenic polymorphisms were determined by PCR-RFLP analysis. The results allowed the full characterization of 67 patients. The mutational spectrum encompasses 34 distinct mutations, being the most frequent IVS10nt-11G>A (14.6%), V388M (10.8%), R261Q (8.2%) and R270K (7.6%), which account for 46% of all mutant alleles. Moreover, 12 different haplotypes were identified and most mutations were associated with a single one. Notably, more than half of the 34 mutations belong to the group of more than 70 mutations already identified in BH(4)-responsive patients, according to BIOPKU database. Fifty one different genotypic combinations were found, most of them in single patients and involving a BH(4)-responsive mutation. In conclusion, a significant number (30-35%) of South Portugal PKU patients may potentially benefit from BH(4) therapy which, combined with a less strict diet, or eventually in special cases as monotherapy, may contribute to reduce nutritional deficiencies and minimize neurological and psychological dysfunctions.
Collapse
Affiliation(s)
- Isabel Rivera
- Metabolism and Genetics Group, Faculty of Pharmacy, iMed.UL-Research Institute for Medicines and Pharmaceutical Sciences,University of Lisbon, Portugal.
| | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Muntau AC, Gersting SW. Phenylketonuria as a model for protein misfolding diseases and for the development of next generation orphan drugs for patients with inborn errors of metabolism. J Inherit Metab Dis 2010; 33:649-58. [PMID: 20824346 DOI: 10.1007/s10545-010-9185-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Revised: 07/22/2010] [Accepted: 07/26/2010] [Indexed: 11/28/2022]
Abstract
The lecture dedicated to Professor Horst Bickel describes the advances, successes, and opportunities concerning the understanding of the biochemical and molecular basis of phenylketonuria and the innovative treatment strategies introduced for these patients during the last 60 years. These concepts were transferred to other inborn errors of metabolism and led to significant reduction in morbidity and to an improvement in quality of life. Important milestones were the successful development of a low-phenylalanine diet for phenylketonuria patients, the recognition of tetrahydrobiopterin as an option to treat these individuals pharmacologically, and finally market approval of this drug. The work related to the discovery of a pharmacological treatment led metabolic researchers and pediatricians to new insights into the molecular processes linked to mutations in the phenylalanine hydroxylase gene at the cellular and structural level. Again, phenylketonuria became a prototype disorder for a previously underestimated but now rapidly expanding group of diseases: protein misfolding disorders with loss of function. Due to potential general biological mechanisms underlying these disorders, the door may soon open to a systematic development of a new class of pharmaceutical products. These pharmacological chaperones are likely to correct misfolding of proteins involved in numerous genetic and nongenetic diseases.
Collapse
Affiliation(s)
- Ania C Muntau
- Dr von Hauner Children's Hospital, Department of Molecular Pediatrics, Ludwig Maximilians University, Lindwurmstrasse 4, 80337 Munich, Germany.
| | | |
Collapse
|
28
|
Leandro J, Simonsen N, Saraste J, Leandro P, Flatmark T. Phenylketonuria as a protein misfolding disease: The mutation pG46S in phenylalanine hydroxylase promotes self-association and fibril formation. Biochim Biophys Acta Mol Basis Dis 2010; 1812:106-20. [PMID: 20937381 DOI: 10.1016/j.bbadis.2010.09.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 09/02/2010] [Accepted: 09/21/2010] [Indexed: 10/19/2022]
Abstract
The missense mutation pG46S in the regulatory (R) domain of human phenylalanine hydroxylase (hPAH), associated with a severe form of phenylketonuria, generates a misfolded protein which is rapidly degraded on expression in HEK293 cells. When overexpressed as a MBP-G46S fusion protein, soluble and fully active tetrameric/dimeric forms are assembled and recovered in a metastable conformational state. When MBP is cleaved off, G46S undergoes a conformational change and self-associates with a lag phase and an autocatalytic growth phase (tetramers≫dimers), as determined by light scattering. The self-association is controlled by pH, ionic strength, temperature, protein concentration and the phosphorylation state of Ser16; the net charge of the protein being a main modulator of the process. A superstoichiometric amount of WT dimers revealed a 2-fold enhancement of the rate of G46S dimer self-association. Electron microscopy demonstrates the formation of higher-order oligomers and linear polymers of variable length, partly as a branching network, and partly as individual long and twisted fibrils (diameter ~145-300Å). The heat-shock proteins Hsp70/Hsp40, Hsp90 and a proposed pharmacological PAH chaperone (3-amino-2-benzyl-7-nitro-4-(2-quinolyl)-1,2-dihydroisoquinolin-1-one) partly inhibit the self-association process. Our data indicate that the G46S mutation results in a N-terminal extension of α-helix 1 which perturbs the wild-type α-β sandwich motif in the R-domain and promotes new intermolecular contacts, self-association and non-amyloid fibril formation. The metastable conformational state of G46S as a MBP fusion protein, and its self-association propensity when released from MBP, may represent a model system for the study of other hPAH missense mutations characterized by misfolded proteins.
Collapse
Affiliation(s)
- João Leandro
- Department of Biomedicine, University of Bergen, Jonas Lies vei 91, N-5009 Bergen, Norway
| | | | | | | | | |
Collapse
|
29
|
Popova NK, Kulikov AV. Targeting tryptophan hydroxylase 2 in affective disorder. Expert Opin Ther Targets 2010; 14:1259-71. [DOI: 10.1517/14728222.2010.524208] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
30
|
Kozich V, Sokolová J, Klatovská V, Krijt J, Janosík M, Jelínek K, Kraus JP. Cystathionine beta-synthase mutations: effect of mutation topology on folding and activity. Hum Mutat 2010; 31:809-19. [PMID: 20506325 PMCID: PMC2966864 DOI: 10.1002/humu.21273] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 04/14/2010] [Indexed: 01/08/2023]
Abstract
Misfolding of mutant enzymes may play an important role in the pathogenesis of cystathionine beta-synthase (CBS) deficiency. We examined properties of a series of 27 mutant variants, which together represent 70% of known alleles observed in patients with homocystinuria due to CBS deficiency. The median amount of SDS-soluble mutant CBS polypeptides in the pellet after centrifugation of bacterial extracts was increased by 50% compared to the wild type. Moreover, mutants formed on average only 12% of tetramers and their median activity reached only 3% of the wild-type enzyme. In contrast to the wild-type CBS about half of mutants were not activated by S-adenosylmethionine. Expression at 18 degrees C substantially increased the activity of five mutants in parallel with increasing the amounts of tetramers. We further analyzed the role of solvent accessibility of mutants as a determinant of their folding and activity. Buried mutations formed on average less tetramers and exhibited 23 times lower activity than the solvent exposed mutations. In summary, our results show that topology of mutations predicts in part the behavior of mutant CBS, and that misfolding may be an important and frequent pathogenic mechanism in CBS deficiency.
Collapse
Affiliation(s)
- Viktor Kozich
- First Faculty of Medicine, Charles University in Prague and General University Hospital in Prague, Institute of Inherited Metabolic Disorders, Prague, Czech Republic.
| | | | | | | | | | | | | |
Collapse
|
31
|
De Silva V, Oldham CD, May SW. L-Phenylalanine concentration in blood of phenylketonuria patients: a modified enzyme colorimetric assay compared with amino acid analysis, tandem mass spectrometry, and HPLC methods. Clin Chem Lab Med 2010; 48:1271-9. [DOI: 10.1515/cclm.2010.271] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
32
|
Santos L, Fonseca C, Starling A, Janu�rio J, Aguiar M, Peixoto M, Carvalho M. Variations in genotype-phenotype correlations in phenylketonuria patients. GENETICS AND MOLECULAR RESEARCH 2010; 9:1-8. [DOI: 10.4238/vol9-1gmr670] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
33
|
Molecular Diagnosis of Phenylketonuria: From Defective Protein to Disease-Causing Gene Mutation. J Med Biochem 2009. [DOI: 10.2478/v10011-009-0021-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Molecular Diagnosis of Phenylketonuria: From Defective Protein to Disease-Causing Gene MutationPhenylketonuria (PKU) is the most common inborn error of amino acid metabolism, with an average incidence of 1/10000 in Caucasians. PKU is caused by more than 500 mutations in the phenylalanine hydroxylase gene (PAH) which result in phenylalanine hydroxylase (PAH) enzyme deficiency. Two approaches, in vitro expression analysis of mutant PAH and genotype-phenotype correlation study, are used for the assessment of severity ofPAHmutations. It has been shown that there is a significant correlation between mutantPAHgenotypes and PKU phenotypes. As a result, the molecular diagnosis is completely shifted toward the detection of mutations in the phenylalanine hydroxylase gene. The study of the molecular basis of PKU in Serbia included identification of the spectrum and frequency ofPAHmutations in Serbian PKU patients and genotype-phenotype correlation analysis. By using both PCR-RFLP and »broad range« DGGE/DNA sequencing analysis, the mutation detection rate reached 97%. Thus, the base for molecular diagnosis, genetic counseling and selection of BH4-responsive PKU patients in Serbia was created.
Collapse
|
34
|
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
|
35
|
The Missense p.S231F Phenylalanine Hydroxylase Gene Mutation Causes Complete Loss of Enzymatic Activity In Vitro. Protein J 2009; 28:294-9. [DOI: 10.1007/s10930-009-9194-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
36
|
Daniele A, Scala I, Cardillo G, Pennino C, Ungaro C, Sibilio M, Parenti G, Esposito L, Zagari A, Andria G, Salvatore F. Functional and structural characterization of novel mutations and genotype-phenotype correlation in 51 phenylalanine hydroxylase deficient families from Southern Italy. FEBS J 2009; 276:2048-59. [DOI: 10.1111/j.1742-4658.2009.06940.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
37
|
Janošík M, Sokolová J, Janošíková B, Krijt J, Klatovská V, Kožich V. Birth prevalence of homocystinuria in Central Europe: frequency and pathogenicity of mutation c.1105C>T (p.R369C) in the cystathionine beta-synthase gene. J Pediatr 2009; 154:431-7. [PMID: 18950795 PMCID: PMC2653617 DOI: 10.1016/j.jpeds.2008.09.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2008] [Revised: 08/11/2008] [Accepted: 09/04/2008] [Indexed: 11/25/2022]
Abstract
OBJECTIVES To estimate the frequency of the cystathionine beta-synthase deficiency caused by c.1105C>T mutation in Central Europe compared to Norway, and to examine the pathogenicity of the corresponding p.R369C mutant enzyme. STUDY DESIGN Mutation c.1105C>T was analyzed in 600 anonymous Czech newborn blood spots. Catalytic activity and quaternary structure of the p.R369C mutant was evaluated after expression in 2 cellular systems. RESULTS Population frequency of the c.1105C>T mutation was 0.005, predicting the birth prevalence of homocystinuria of 1:40000, which increased to 1:15500 in a model including 10 additional mutations. In Escherichia coli the p.R369C mutant misfolded, and its activity was severely reduced, and expression in Chinese hamster ovary cells enabled proper folding with activity decreased to 63% of the wild-type enzyme. This decreased activity was not due to impaired K(m) for both substrates but resulted from V(max) lowered to 55% of the normal cystathionine beta-synthase enzyme. CONCLUSIONS The c.1105C>T (p.R369C) allele is common also in the Czech population. Although the p.R369C mutation impairs folding and decreases velocity of the enzymatic reaction, our data are congruent with rather mild clinical phenotype in homozygotes or compound heterozygotes carrying this mutation.
Collapse
Affiliation(s)
| | | | | | | | | | - Viktor Kožich
- Institute of Inherited Metabolic Disorders, Charles University in Prague—1st Faculty of Medicine, Prague, Czech Republic
| |
Collapse
|
38
|
Discovery science: uncovering new questions. Pediatr Crit Care Med 2008; 9:543-4. [PMID: 18779706 DOI: 10.1097/pcc.0b013e3181849f95] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
39
|
Haavik J, Blau N, Thöny B. Mutations in human monoamine-related neurotransmitter pathway genes. Hum Mutat 2008; 29:891-902. [PMID: 18444257 DOI: 10.1002/humu.20700] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Biosynthesis and metabolism of serotonin and catecholamines involve at least eight individual enzymes that are mainly expressed in tissues derived from the neuroectoderm, e.g., the central nervous system (CNS), pineal gland, adrenal medulla, enterochromaffin tissue, sympathetic nerves, and ganglia. Some of the enzymes appear to have additional biological functions and are also expressed in the heart and various other internal organs. The biosynthetic enzymes are tyrosine hydroxylase (TH), tryptophan hydroxylases type 1 and 2 (TPH1, TPH2), aromatic amino acid decarboxylase (AADC), dopamine beta-hydroxylase (DbetaH), and phenylethanolamine N-methyltransferase (PNMT), and the specific catabolic enzymes are monoamine oxidase A (MAO-A) and catechol O-methyltransferase (COMT). For the TH, DDC, DBH, and MAOA genes, many single nucleotide polymorphisms (SNPs) with unknown function, and small but increasing numbers of cases with autosomal recessive mutations have been recognized. For the remaining genes (TPH1, TPH2, PNMT, and COMT) several different genetic markers have been suggested to be associated with regulation of mood, pain perception, and aggression, as well as psychiatric disturbances such as schizophrenia, depression, suicidality, and attention deficit/hyperactivity disorder. The genetic markers may either have a functional role of their own, or be closely linked to other unknown functional variants. In the future, molecular testing may become important for the diagnosis of such conditions. Here we present an overview on mutations and polymorphisms in the group of genes encoding monoamine neurotransmitter metabolizing enzymes. At the same time we propose a unified nomenclature for the nucleic acid aberrations in these genes. New variations or details on mutations will be updated in the Pediatric Neurotransmitter Disorder Data Base (PNDDB) database (www.bioPKU.org).
Collapse
Affiliation(s)
- Jan Haavik
- Department of Biomedicine, University of Bergen, Norway
| | | | | |
Collapse
|
40
|
Gersting SW, Kemter KF, Staudigl M, Messing DD, Danecka MK, Lagler FB, Sommerhoff CP, Roscher AA, Muntau AC. Loss of function in phenylketonuria is caused by impaired molecular motions and conformational instability. Am J Hum Genet 2008; 83:5-17. [PMID: 18538294 PMCID: PMC2443833 DOI: 10.1016/j.ajhg.2008.05.013] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 05/09/2008] [Accepted: 05/17/2008] [Indexed: 11/21/2022] Open
Abstract
A significant share of patients with phenylalanine hydroxylase (PAH) deficiency benefits from pharmacological doses of tetrahydrobiopterin (BH(4)), the natural PAH cofactor. Phenylketonuria (PKU) is hypothesized to be a conformational disease, with loss of function due to protein destabilization, and the restoration of enzyme function that is observed in BH(4) treatment might be transmitted by correction of protein misfolding. To elucidate the molecular basis of functional impairment in PAH deficiency, we investigated the impact of ten PAH gene mutations identified in patients with BH(4)-responsiveness on enzyme kinetics, stability, and conformation of the protein (F55L, I65S, H170Q, P275L, A300S, S310Y, P314S, R408W, Y414C, Y417H). Residual enzyme activity was generally high, but allostery was disturbed in almost all cases and pointed to altered protein conformation. This was confirmed by reduced proteolytic stability, impaired tetramer assembly or aggregation, increased hydrophobicity, and accelerated thermal unfolding--with particular impact on the regulatory domain--observed in most variants. Three-dimensional modeling revealed the involvement of functionally relevant amino acid networks that may communicate misfolding throughout the protein. Our results substantiate the view that PAH deficiency is a protein-misfolding disease in which global conformational changes hinder molecular motions essential for physiological enzyme function. Thus, PKU has evolved from a model of a genetic disease that leads to severe neurological impairment to a model of a treatable protein-folding disease with loss of function.
Collapse
Affiliation(s)
- Søren W. Gersting
- Department of Molecular Pediatrics, Children's Research Center, Dr. von Hauner Children's Hospital, Ludwig Maximilians University, 80337 Munich, Germany
| | - Kristina F. Kemter
- Department of Molecular Pediatrics, Children's Research Center, Dr. von Hauner Children's Hospital, Ludwig Maximilians University, 80337 Munich, Germany
| | - Michael Staudigl
- Department of Molecular Pediatrics, Children's Research Center, Dr. von Hauner Children's Hospital, Ludwig Maximilians University, 80337 Munich, Germany
| | - Dunja D. Messing
- Department of Molecular Pediatrics, Children's Research Center, Dr. von Hauner Children's Hospital, Ludwig Maximilians University, 80337 Munich, Germany
| | - Marta K. Danecka
- Department of Molecular Pediatrics, Children's Research Center, Dr. von Hauner Children's Hospital, Ludwig Maximilians University, 80337 Munich, Germany
| | - Florian B. Lagler
- Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, 6020 Innsbruck, Austria
| | - Christian P. Sommerhoff
- Department of Clinical Chemistry and Clinical Biochemistry, Surgical Clinic, Ludwig Maximilians University, 80337 Munich, Germany
| | - Adelbert A. Roscher
- Department of Molecular Pediatrics, Children's Research Center, Dr. von Hauner Children's Hospital, Ludwig Maximilians University, 80337 Munich, Germany
| | - Ania C. Muntau
- Department of Molecular Pediatrics, Children's Research Center, Dr. von Hauner Children's Hospital, Ludwig Maximilians University, 80337 Munich, Germany
| |
Collapse
|
41
|
Bercovich D, Elimelech A, Zlotogora J, Korem S, Yardeni T, Gal N, Goldstein N, Vilensky B, Segev R, Avraham S, Loewenthal R, Schwartz G, Anikster Y. Genotype-phenotype correlations analysis of mutations in the phenylalanine hydroxylase (PAH) gene. J Hum Genet 2008; 53:407-418. [PMID: 18299955 DOI: 10.1007/s10038-008-0264-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2007] [Accepted: 01/28/2008] [Indexed: 10/22/2022]
Abstract
The aims of our research were to define the genotype-phenotype correlations of mutations in the phenylalanine hydroxylase (PAH) gene that cause phenylketonuria (PKU) among the Israeli population. The mutation spectrum of the PAH gene in PKU patients in Israel is described, along with a discussion on genotype-phenotype correlations. By using polymerase chain reaction/denaturing high-performance liquid chromatography (PCR/dHPLC) and DNA sequencing, we screened all exons of the PAH gene in 180 unrelated patients with four different PKU phenotypes [classic PKU, moderate PKU, mild PKU, and mild hyperphenylalaninemia (MHP)]. In 63.2% of patient genotypes, the metabolic phenotype could be predicted, though evidence is also found for both phenotypic inconsistencies among subjects with more than one type of mutation in the PAH gene. Data analysis revealed that about 25% of patients could participate in the future in (6R)-L: -erythro-5, 6, 7, 8-tetrahydrobiopterin (BH4) treatment trials according to their mutation genotypes. This study enables us to construct a national database in Israel that will serve as a valuable tool for genetic counseling and a prognostic evaluation of future cases of PKU.
Collapse
Affiliation(s)
- Dani Bercovich
- MIGAL, Galilee Technology Center, Human Molecular Genetics and Pharmacogenetics Laboratory, Kiryat Shmona, Israel. .,Tel-Hai Academic College, Upper Galilee, Israel.
| | - Arava Elimelech
- MIGAL, Galilee Technology Center, Human Molecular Genetics and Pharmacogenetics Laboratory, Kiryat Shmona, Israel
| | - Joel Zlotogora
- Department of Genetic Community, Public Health Services, Health Ministry and Hebrew University, Jerusalem, Israel
| | - Sigal Korem
- MIGAL, Galilee Technology Center, Human Molecular Genetics and Pharmacogenetics Laboratory, Kiryat Shmona, Israel.,Tel-Hai Academic College, Upper Galilee, Israel
| | - Tal Yardeni
- MIGAL, Galilee Technology Center, Human Molecular Genetics and Pharmacogenetics Laboratory, Kiryat Shmona, Israel
| | - Nurit Gal
- Metabolic Disease Unit, Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel
| | - Nurit Goldstein
- Metabolic Disease Unit, Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel
| | - Bela Vilensky
- Metabolic Disease Unit, Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel
| | - Roni Segev
- Metabolic Disease Unit, Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel
| | - Smadar Avraham
- Metabolic Disease Unit, Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel
| | - Ron Loewenthal
- Tissue Typing Unit and Safra Children Hospital, Sheba Medical Center, Tel-Hashomer, Israel.,Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Gerard Schwartz
- Metabolic Disease Unit, Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel
| | - Yair Anikster
- Metabolic Disease Unit, Safra Children's Hospital, Sheba Medical Center, Tel-Hashomer, Israel.,Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| |
Collapse
|
42
|
Daniele A, Cardillo G, Pennino C, Carbone MT, Scognamiglio D, Esposito L, Correra A, Castaldo G, Zagari A, Salvatore F. Five human phenylalanine hydroxylase proteins identified in mild hyperphenylalaninemia patients are disease-causing variants. Biochim Biophys Acta Mol Basis Dis 2008; 1782:378-84. [PMID: 18346471 DOI: 10.1016/j.bbadis.2008.01.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 01/26/2008] [Accepted: 01/29/2008] [Indexed: 10/22/2022]
Abstract
Hyperphenylalaninemia is a group of autosomal recessive disorders caused by a wide range of phenylalanine hydroxylase (PAH) gene variants. To study the effects of mutations on PAH activity, we have reproduced five mutations (p.N223Y, p.R297L, p.F382L, p.K398N and p.Q419R) that we recently identified in a population of Southern Italy. Transient expression of mutant full-length cDNAs in human HEK293 cells yielded PAH variants whose l-phenylalanine hydroxylase activity was between 40% and 70% that of the wild-type enzyme. Moreover, Western blot analysis revealed a 50-kD monomer in all mutants thereby indicating normal synthesis of the mutant proteins. Because of the clinical mild nature of the phenotypes we performed an in vivo BH4 loading test. This was positive in all tested patients, which indicates that they are likely to respond to the coenzyme in vivo. We also analysed the environment of each mutation site in the available crystal structures of PAH by using molecular graphics tools. The structural alteration produced by each mutation was elucidated and correlated to the mutated properties of the mutant enzymes. All the data obtained demonstrate the disease-causing nature of the five novel variants.
Collapse
Affiliation(s)
- Aurora Daniele
- CEINGE - Biotecnologie Avanzate Scarl, Via Comunale Margherita, 482, 80145, Naples, Italy
| | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Martinez A, Calvo AC, Teigen K, Pey AL. Rescuing Proteins of Low Kinetic Stability by Chaperones and Natural Ligands: Phenylketonuria, a Case Study. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2008; 83:89-134. [DOI: 10.1016/s0079-6603(08)00603-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
44
|
Huang Y, Choi MY, Au SWN, Au DMY, Lam VMS, Engel PC. Purification and detailed study of two clinically different human glucose 6-phosphate dehydrogenase variants, G6PD(Plymouth) and G6PD(Mahidol): Evidence for defective protein folding as the basis of disease. Mol Genet Metab 2008; 93:44-53. [PMID: 17959407 DOI: 10.1016/j.ymgme.2007.08.122] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2007] [Revised: 08/17/2007] [Accepted: 08/18/2007] [Indexed: 11/23/2022]
Abstract
In an attempt to investigate the molecular mechanism underlying human glucose-6-phosphate dehydrogenase (G6PD) deficiency caused by two mutations, G6PD(Plymouth) (G163D) and G6PD(Mahidol) (G163S), the two variants were constructed by site-directed mutagenesis and expressed in G6PD-deficient E. coli DF 213 cells. A first indication of impaired folding came from problems in expressing these clinical mutants, which were only overcome by lowering the growth temperature or co-expressing with molecular chaperones (GroEL and GroES). Both strategies significantly increased soluble expression of recombinant G6PD(Plymouth) and G6PD(Mahidol), judged by both G6PD activity in extracts and the amount of immunoreactive protein. Using a modified 3-step protocol, the two mutant enzymes were successfully purified for the first time. Steady-state kinetic parameters (K(m) for NADP(+), K(m) for G6P and k(cat)) of the two mutants are very similar to the wild-type values, indicating that the catalytic efficiency of the two mutants remains unchanged. The two mutants are, however, markedly less stable than wild-type G6PD in both thermostability and urea-induced inactivation tests. In a typical experiment at 37 degrees C and pH 7.2 after 24h G6PD WT, G6PD(Mahidol) and G6PD(Plymouth) retained 58.3%, 27.0% and 3.9%, respectively, of their corresponding initial activity. The stability of all three enzymes is enhanced by addition of NADP(+). According to unfolding and refolding experiments, the two mutants are impaired in their folding properties. Thus structural instability appears to be the molecular basis of the clinical phenotype in G6PD(Plymouth) and G6PD(Mahidol) and in particular of the differing clinical severity of the two mutations. The 3-D structure solved for G6PD(Canton) allows an interpretation of these effects in terms of steric hindrance.
Collapse
Affiliation(s)
- Yuxiang Huang
- Department of Biochemistry, The University of Hong Kong, Hong Kong SAR, China
| | | | | | | | | | | |
Collapse
|
45
|
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
|
46
|
Daniele A, Cardillo G, Pennino C, Carbone MT, Scognamiglio D, Correra A, Pignero A, Castaldo G, Salvatore F. Molecular epidemiology of phenylalanine hydroxylase deficiency in Southern Italy: a 96% detection rate with ten novel mutations. Ann Hum Genet 2006; 71:185-93. [PMID: 17096675 DOI: 10.1111/j.1469-1809.2006.00328.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hyperphenylalaninemia (HPA) comprises a group of autosomal recessive disorders mainly caused by phenylalanine hydroxylase (PAH) gene mutations. We investigated PAH mutations in 126 HPA patients from Southern Italy who were identified in a neonatal screening program. The promoter, coding and exon-flanking intronic sequences of the PAH gene were amplified and sequenced. Mutations were identified in 240/249 alleles (detection rate: 96.4%). We found 60 gene variants; the most frequent were p.R261Q (15.7% of alleles), p.A403V (11.6% of alleles) and c.1066-11G > A (8.8% of alleles). The remaining mutations were rare, and ten are novel. This mutation epidemiology differs from that reported for Northern Italy and other European countries. We also identified several discordant genotype/phenotype correlations. About two-thirds of all mild phenylketonuria patients showed at least one tetrahydrobiopterin (BH4)-responsive mutation, and are thus candidates for a customized therapeutic approach.
Collapse
Affiliation(s)
- A Daniele
- CEINGE-Biotecnologie Avanzate, scarl, Naples, Italy.
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Abstract
Protein misfolding is a common event in living cells. In young and healthy cells, the misfolded protein load is disposed of by protein quality control (PQC) systems. In aging cells and in cells from certain individuals with genetic diseases, the load may overwhelm the PQC capacity, resulting in accumulation of misfolded proteins. Dependent on the properties of the protein and the efficiency of the PQC systems, the accumulated protein may be degraded or assembled into toxic oligomers and aggregates. To illustrate this concept, we discuss a number of very different protein misfolding diseases including phenylketonuria, Parkinson's disease, alpha-1-antitrypsin deficiency, familial neurohypophyseal diabetes insipidus, and short-chain acyl-CoA dehydrogenase deficiency. Despite the differences, an emerging paradigm suggests that the cellular effects of protein misfolding provide a common framework that may contribute to the elucidation of the cell pathology and guide intervention and treatment strategies of many genetic and age-dependent diseases.
Collapse
Affiliation(s)
- Niels Gregersen
- Research Unit for Molecular Medicine, Institute of Clinical Medicine, Aarhus University Hospital and Faculty of Health Sciences, University of Aarhus, Skejby Sygehus, 8200 Aarhus N, Denmark.
| | | | | | | |
Collapse
|
48
|
Gregersen N. Protein misfolding disorders: pathogenesis and intervention. J Inherit Metab Dis 2006; 29:456-70. [PMID: 16763918 DOI: 10.1007/s10545-006-0301-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2005] [Accepted: 02/02/2006] [Indexed: 11/26/2022]
Abstract
Newly synthesized proteins in the living cell must go through a folding process to attain their functional structure. To achieve this in an efficient fashion, all organisms, including humans, have evolved a large set of molecular chaperones that assist the folding as well as the maintenance of the functional structure of cellular proteins. Aberrant proteins, the result of production errors, inherited or acquired amino acid substitutions or damage, especially oxidative modifications, can in many cases not fold correctly and will be trapped in misfolded conformations. To rid the cell of misfolded proteins, the living cell contains a large number of intracellular proteases, e.g. the proteasome, which together with the chaperones comprise the cellular protein quality control systems. Many inherited disorders due to amino acid substitutions exhibit loss-of-function pathogenesis because the aberrant protein is eliminated by one of the protein quality control systems. Examples are cystic fibrosis and phenylketonuria. However, not all aberrant proteins can be eliminated and the misfolded protein may accumulate and form toxic oligomeric and/or aggregated inclusions. In this case the loss of function may be accompanied by a gain-of-function pathogenesis, which in many cases determines the pathological and clinical features. Examples are Parkinson and Huntington diseases. Although a number of strategies have been tried to decrease the amounts of accumulated and aggregated proteins, a likely future strategy seems to be the use of chemical or pharmacological chaperones with specific effects on the misfolded protein in question. Positive examples are enzyme enhancement in a number of lysosomal disorders.
Collapse
Affiliation(s)
- N Gregersen
- Research Unit for Molecular Medicine, Institute of Clinical Medicine, Aarhus University Hospital, Skejby Sygehus, 8200, Aarhus N, Denmark
| |
Collapse
|
49
|
Peyne É, Meyer M, Vasson MP. Prise en charge nutritionnelle du jeune patient phénylcétonurique. NUTR CLIN METAB 2006. [DOI: 10.1016/j.nupar.2005.12.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
50
|
Zhang X, Beaulieu JM, Gainetdinov RR, Caron MG. Functional polymorphisms of the brain serotonin synthesizing enzyme tryptophan hydroxylase-2. Cell Mol Life Sci 2006; 63:6-11. [PMID: 16378243 PMCID: PMC2792355 DOI: 10.1007/s00018-005-5417-4] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Many neuropsychiatric disorders are considered to be related to the dysregulation of brain serotonergic neurotransmission. Tryptophan hydroxylase-2 (TPH2) is the neuronal-specific enzyme that controls brain serotonin synthesis. There is growing genetic evidence for the possible involvement of TPH2 in serotonin-related neuropsychiatric disorders; however, the degree of genetic variation in TPH2 and, in particular, its possible functional consequences remain unknown. In this short review, we will summarize some recent findings with respect to the functional analysis of TPH2.
Collapse
Affiliation(s)
- X. Zhang
- Department of Cell Biology, and Center for Models of Human Disease, Institute for Genome Sciences and Policy, Duke University Medical Center, Box 3287, Durham, North Carolina 27710 USA
| | - J.-M. Beaulieu
- Department of Cell Biology, and Center for Models of Human Disease, Institute for Genome Sciences and Policy, Duke University Medical Center, Box 3287, Durham, North Carolina 27710 USA
| | - R. R. Gainetdinov
- Department of Cell Biology, and Center for Models of Human Disease, Institute for Genome Sciences and Policy, Duke University Medical Center, Box 3287, Durham, North Carolina 27710 USA
| | - M. G. Caron
- Department of Cell Biology, and Center for Models of Human Disease, Institute for Genome Sciences and Policy, Duke University Medical Center, Box 3287, Durham, North Carolina 27710 USA
| |
Collapse
|