1
|
Himmelreich N, Ramón-Maiques S, Navarrete R, Castejon-Fernandez N, Garbade SF, Martinez A, Desviat LR, Pérez B, Blau N. Significance of utilizing in silico structural analysis and phenotypic data to characterize phenylalanine hydroxylase variants: A PAH landscape. Mol Genet Metab 2024; 142:108514. [PMID: 38905920 DOI: 10.1016/j.ymgme.2024.108514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Revised: 06/10/2024] [Accepted: 06/12/2024] [Indexed: 06/23/2024]
Abstract
Phenylketonuria (PKU) is a genetic disorder caused by variations in the phenylalanine hydroxylase (PAH) gene. Among the 3369 reported PAH variants, 33.7% are missense alterations. Unfortunately, 30% of these missense variants are classified as variants of unknown significance (VUS), posing challenges for genetic risk assessment. In our study, we focused on analyzing 836 missense PAH variants following the American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines specified by ClinGen PAH Variant Curation Expert Panel (VCEP) criteria. We utilized and compared variant annotator tools like Franklin and Varsome, conducted 3D structural analysis of PAH, and examined active and regulatory site hotspots. In addition, we assessed potential splicing effect of apparent missense variants. By evaluating phenotype data from 22962 PKU patients, our aim was to reassess the pathogenicity of missense variants. Our comprehensive approach successfully reclassified 309 VUSs out of 836 missense variants as likely pathogenic or pathogenic (37%), upgraded 370 likely pathogenic variants to pathogenic, and reclassified one previously considered likely benign variant as likely pathogenic. Phenotypic information was available for 636 missense variants, with 441 undergoing 3D structural analysis and active site hotspot identification for 180 variants. After our analysis, only 6% of missense variants were classified as VUSs, and three of them (c.23A>C/p.Asn8Thr, c.59_60delinsCC/p.Gln20Pro, and c.278A >T/p.Asn93Ile) may be influenced by abnormal splicing. Moreover, a pathogenic variant (c.168G>T/p.Glu56Asp) was identified to have a risk exceeding 98% for modifications of the consensus splice site, with high scores indicating a donor loss of 0.94. The integration of ACMG/AMP guidelines with in silico structural analysis and phenotypic data significantly reduced the number of missense VUSs, providing a strong basis for genetic counseling and emphasizing the importance of metabolic phenotype information in variant curation. This study also sheds light on the current landscape of PAH variants.
Collapse
Affiliation(s)
- Nastassja Himmelreich
- Dietmar-Hopp Metabolic Center and Centre for Pediatrics and Adolescent Medicine, University Children's Hospital, Heidelberg, Germany
| | - Santiago Ramón-Maiques
- Instituto de Biomedicina de Valencia (IBV), CSIC, Valencia, Spain; Group 739, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER)-Instituto de Salud Carlos III, Valencia, Spain
| | - Rosa Navarrete
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular, CIBERER, IdiPAZ, Universidad Autónoma de Madrid, Madrid, Spain
| | - Natalia Castejon-Fernandez
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular, CIBERER, IdiPAZ, Universidad Autónoma de Madrid, Madrid, Spain
| | - Sven F Garbade
- Dietmar-Hopp Metabolic Center and Centre for Pediatrics and Adolescent Medicine, University Children's Hospital, Heidelberg, Germany
| | - Aurora Martinez
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Lourdes R Desviat
- Centro de Biología Molecular Severo Ochoa UAM-CSIC, CIBERER, IdiPAZ, Universidad Autónoma de Madrid, Madrid, Spain
| | - Belén Pérez
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular, CIBERER, IdiPAZ, Universidad Autónoma de Madrid, Madrid, Spain.
| | - Nenad Blau
- Divisions of Metabolism, University Children's Hospital, Zürich, Switzerland.
| |
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
|
Tendi EA, Morello G, Guarnaccia M, La Cognata V, Petralia S, Messina MA, Meli C, Fiumara A, Ruggieri M, Cavallaro S. Detection of Single-Nucleotide and Copy Number Defects Underlying Hyperphenylalaninemia by Next-Generation Sequencing. Biomedicines 2023; 11:1899. [PMID: 37509538 PMCID: PMC10377317 DOI: 10.3390/biomedicines11071899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 06/27/2023] [Accepted: 06/29/2023] [Indexed: 07/30/2023] Open
Abstract
Hyperphenylalaninemia (HPA) is the most common inherited amino acid metabolism disorder characterized by serious clinical manifestations, including irreversible brain damage, intellectual deficiency and epilepsy. Due to its extensive genic and allelic heterogeneity, next-generation sequencing (NGS) technology may help to identify the molecular basis of this genetic disease. Herein, we describe the development and validation of a targeted NGS (tNGS) approach for the simultaneous detection of single-nucleotide changes and copy number variations (CNVs) in genes associated with HPA (PAH, GCH1, PTS, QDPR, PCBD1, DNAJC12) or useful for its differential diagnosis (SPR). Our tNGS approach offers the possibility to detail, with a high accuracy and in a single workflow, the combined effect of a broader spectrum of genomic variants in a comprehensive view, providing a significant step forward in the development of optimized patient care and management.
Collapse
Affiliation(s)
- Elisabetta Anna Tendi
- Biomedical Sciences Department, Institute for Biomedical Research and Innovation, National Research Council, Via Paolo Gaifami 18, 95026 Catania, Italy
| | - Giovanna Morello
- Biomedical Sciences Department, Institute for Biomedical Research and Innovation, National Research Council, Via Paolo Gaifami 18, 95026 Catania, Italy
| | - Maria Guarnaccia
- Biomedical Sciences Department, Institute for Biomedical Research and Innovation, National Research Council, Via Paolo Gaifami 18, 95026 Catania, Italy
| | - Valentina La Cognata
- Biomedical Sciences Department, Institute for Biomedical Research and Innovation, National Research Council, Via Paolo Gaifami 18, 95026 Catania, Italy
| | - Salvatore Petralia
- Department of Drug and Health Sciences, University of Catania, 95125 Catania, Italy
| | - Maria Anna Messina
- Regional Reference Center for the Treatment and Control of Congenital Metabolic Diseases of Childhood, Department of Clinical and Experimental Medicine, University Hospital Policlinico "Rodolico-San Marco", 95123 Catania, Italy
| | - Concetta Meli
- Regional Reference Center for the Treatment and Control of Congenital Metabolic Diseases of Childhood, Department of Clinical and Experimental Medicine, University Hospital Policlinico "Rodolico-San Marco", 95123 Catania, Italy
| | - Agata Fiumara
- Regional Reference Center for the Treatment and Control of Congenital Metabolic Diseases of Childhood, Department of Clinical and Experimental Medicine, University Hospital Policlinico "Rodolico-San Marco", 95123 Catania, Italy
| | - Martino Ruggieri
- Unit of Rare Diseases of the Nervous System in Childhood, Section of Pediatrics and Child Neuropsychiatry, Department of Clinical and Experimental Medicine, University Hospital Policlinico "Rodolico-San Marco", 95123 Catania, Italy
| | - Sebastiano Cavallaro
- Biomedical Sciences Department, Institute for Biomedical Research and Innovation, National Research Council, Via Paolo Gaifami 18, 95026 Catania, Italy
| |
Collapse
|
4
|
Rovelli V, Cefalo G, Ercoli V, Zuvadelli J, Olivia T, Graziani D, Luisella A, Bassi D, Re Dionigi A, Selmi R, Paci S, Salvatici E, Banderali G. Hyperphenylalaninemias genotyping: Results of over 60 years of history in Lombardy, Italy. Endocrinol Diabetes Metab 2023; 6:e396. [PMID: 36537053 PMCID: PMC10000623 DOI: 10.1002/edm2.396] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/11/2022] [Accepted: 11/23/2022] [Indexed: 03/11/2023] Open
Abstract
BACKGROUND Hyperphenylalaninemias (HPA) are due to several gene mutations, of which the PAH gene is the most frequently involved. Prevalence and incidence of disease vary between populations, with genotype/phenotype correlations not always capable to correctly predict disease severity. The aim of this study was to give an overview of PAH mutations among one of the largest cohort of patients among Europe, born in Lombardy (Italy) starting from late 1970 s and including over a 60 years of activity; furthermore, to evaluate and discuss identified genotype/phenotype correlations and related reliability. PATIENTS/METHODS Eight hundred and twenty-six HPA patients in current follow-up at the San Paolo Hospital in Milan (Italy) were retrospectively reviewed, including molecular results and allelic phenotype and genotype values (attributed on the basis of the APV/GPV system) to verify genotype-phenotype correlations. RESULTS A total of 166 different PAH variants were reviewed; of those, seven variants were identified as not previously described in literature. Most frequently reported variant was p.Ala403Val, followed by p.Arg261Gln, p.Val245Ala, IVS10-11 g>a, p.Tyr414Cys and p.Leu48Ser. Phenotype prediction, based on APV/GPV, matched the actual phenotype in most cases, but not always. CONCLUSION/DISCUSSION The cohort of patients included in this study constitute a representative sample of the HPA population worldwide. Studies on this sample may allow to improve clinical and genetic evaluation performances for affected patients, consequently to develop personalized medicine interventions and provide more precise indications on the correct treatment approach based on the accumulated evidence, also in light of a prognostically reliable but not always conclusive APV/GPV system.
Collapse
Affiliation(s)
- Valentina Rovelli
- Clinical Department of Pediatrics, Inborn Errors of Metabolism Unit, San Paolo Hospital, ASST Santi Paolo e CarloUniversity of MilanMilanItaly
| | - Graziella Cefalo
- Clinical Department of Pediatrics, Inborn Errors of Metabolism Unit, San Paolo Hospital, ASST Santi Paolo e CarloUniversity of MilanMilanItaly
| | - Vittoria Ercoli
- Clinical Department of Pediatrics, Inborn Errors of Metabolism Unit, San Paolo Hospital, ASST Santi Paolo e CarloUniversity of MilanMilanItaly
| | - Juri Zuvadelli
- Clinical Department of Pediatrics, Inborn Errors of Metabolism Unit, San Paolo Hospital, ASST Santi Paolo e CarloUniversity of MilanMilanItaly
| | - Turri Olivia
- Department of Laboratory Diagnostic TechnologiesSan Paolo Hospital, ASST Santi Paolo e CarloMilanItaly
| | - Daniela Graziani
- Department of Laboratory Diagnostic TechnologiesSan Paolo Hospital, ASST Santi Paolo e CarloMilanItaly
| | - Alberti Luisella
- Regional Laboratory of Newborn Screening, Department of Women, Mothers and Neonatal Care, Children's Hospital “V. Buzzi”ASST Fatebenefratelli SaccoMilanItaly
| | - Davide Bassi
- Clinical Department of Pediatrics, Inborn Errors of Metabolism Unit, San Paolo Hospital, ASST Santi Paolo e CarloUniversity of MilanMilanItaly
| | - Alice Re Dionigi
- Clinical Department of Pediatrics, Inborn Errors of Metabolism Unit, San Paolo Hospital, ASST Santi Paolo e CarloUniversity of MilanMilanItaly
| | - Raed Selmi
- Clinical Department of Pediatrics, Inborn Errors of Metabolism Unit, San Paolo Hospital, ASST Santi Paolo e CarloUniversity of MilanMilanItaly
| | - Sabrina Paci
- Clinical Department of Pediatrics, Inborn Errors of Metabolism Unit, San Paolo Hospital, ASST Santi Paolo e CarloUniversity of MilanMilanItaly
| | - Elisabetta Salvatici
- Clinical Department of Pediatrics, Inborn Errors of Metabolism Unit, San Paolo Hospital, ASST Santi Paolo e CarloUniversity of MilanMilanItaly
| | - Giuseppe Banderali
- Clinical Department of Pediatrics, Inborn Errors of Metabolism Unit, San Paolo Hospital, ASST Santi Paolo e CarloUniversity of MilanMilanItaly
| |
Collapse
|
5
|
Luo X, Wang R, Sun Y, Qiu W, Lu D, Wang Y, Gong Z, Zhang H, Han L, Liang L, Gu X, Yu Y, Xiao B. Deep Intronic PAH Variants Explain Missing Heritability in Hyperphenylalaninemia. J Mol Diagn 2023; 25:284-294. [PMID: 36849017 DOI: 10.1016/j.jmoldx.2023.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 01/18/2023] [Accepted: 02/02/2023] [Indexed: 02/27/2023] Open
Abstract
Phenylalanine hydroxylase (PAH) deficiency or phenylketonuria (PKU) is the most common cause of hyperphenylalaninemia (HPA), and approximately 5% of patients remain genetically unsolved. Identifying deep intronic PAH variants may help improve their molecular diagnostic rate. Next-generation sequencing was utilized to detect the whole PAH gene in 96 patients with genetically unsolved HPA from 2013 to 2022. The effects of deep intronic variants on pre-mRNA splicing were investigated by minigene-based assay. The allelic phenotype values of recurrent deep intronic variants were calculated. Twelve deep intronic PAH variants, located in intron 5 (c.509+434C>T), intron 6 (c.706+288T>G, c.706+519T>C, c.706+531T>C, c.706+535G>T, c.706+600A>C, c.706+603T>G, and c.706+608A>C), intron 10 (c.1065+241C>A and c.1065+258C>A), and intron 11 (c.1199+502A>T and c.1199+745T>A) were identified in 80.2% (77/96) patients. Ten of the 12 variants were novel, and they all generated pseudoexons in mRNA, leading to frameshift or lengthened proteins. The most prevalent deep intronic variant was c.1199+502A>T, followed by c.1065+241C>A, c.1065+258C>A, and c.706+531T>C. The metabolic phenotypes of the four variants were assigned as classic PKU, mild HPA, mild HPA, and mild PKU, respectively. The results suggest that deep intronic PAH variants improved the diagnostic rate from 95.3% to 99.3% in the overall patients with HPA. Our data demonstrate the importance of assessing noncoding variants in genetic diseases. Pseudoexon inclusion caused by deep intronic variants could represent a recurrent mechanism.
Collapse
Affiliation(s)
- Xiaomei Luo
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Ruifang Wang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Yu Sun
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Wenjuan Qiu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Deyun Lu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Yu Wang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Zhuwen Gong
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Huiwen Zhang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Lianshu Han
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Lili Liang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Xuefan Gu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China
| | - Yongguo Yu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China.
| | - Bing Xiao
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China; Shanghai Institute for Pediatric Research, Shanghai, China.
| |
Collapse
|
6
|
Compound Heterozygosis in AADC Deficiency and Its Complex Phenotype in Terms of AADC Protein Population. Int J Mol Sci 2022; 23:ijms231911238. [PMID: 36232540 PMCID: PMC9570296 DOI: 10.3390/ijms231911238] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 09/21/2022] [Accepted: 09/22/2022] [Indexed: 11/16/2022] Open
Abstract
Aromatic amino acid decarboxylase (AADC) deficiency is a rare monogenic disease due to mutations in the ddc gene producing AADC, a homodimeric pyridoxal 5′-phosphate-dependent enzyme. The disorder is often fatal in the first decade and is characterized by profound motor impairments and developmental delay. In the last two years, there has been a net rise in the number of patients and variants identified, maybe also pushed by the ongoing gene therapy trials. The majority of the identified genotypes are compound heterozygous (about 70%). Efforts are underway to reach early diagnosis, find possible new markers/new fast methods, and predict clinical outcome. However, no clear correlation of genotype-to-phenotype exists to date. Nevertheless, for homozygous patients, reliable results have been obtained using genetic methods combined with available computational tools on crystal structures corroborated by biochemical investigations on recombinant homodimeric AADC variants that have been obtained and characterized in solution. For these variants, the molecular basis for the defect has been suggested and validated, since it correlates quite well with mildness/severity of the homozygous phenotype. Instead, prediction for compound heterozygous patients is more difficult since complementation effects could happen. Here, by analyzing the existing literature on compound heterozygosity in AADC deficiency and other genetic disorders, we highlight that, in order to assess pathogenicity, the measurement of activity of the AADC heterodimeric variant should be integrated by bioinformatic, structural, and functional data on the whole protein constellation theoretically present in such patients. A wider discussion on symptomatic heterozygosity in AADC deficiency is also presented.
Collapse
|
7
|
Khaghani F, Eshraghi P, Hamzehloei T. Tetrahydrobiopterin responsiveness in Phenylalanine hydroxylase deficient patients from North-east of Iran: Genotype-phenotype correlation, identification of a novel mutation and 7 new responsive genotypes. Eur J Med Genet 2022; 65:104536. [PMID: 35690318 DOI: 10.1016/j.ejmg.2022.104536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/03/2022] [Accepted: 06/05/2022] [Indexed: 11/03/2022]
Abstract
Phenylalanine hydroxylase enzyme defects result in a hereditary metabolic disorder called phenylketonuria. Sapropterin (tetrahydrobiopterin) is one of the treatment strategies for this disorder. Even though a correlation between genotype and BH4 responsiveness was established by earlier studies, a subset of mutations often presented inconsistent responses and/or phenotypes. Different genetic background is one of the potential reasons for this fact. In this study, the genotype of a total of 34 PAH deficient patients from Khorasan-Razavi providence in the north-east of Iran was obtained. Among this patients, 21 individuals took the 24 h and 48 h BH4 loading test and if the result was positive, their Phenylalanine tolerance was assessed. It is the first study of its type in patients from Iran to evaluate genotype role in predicting the most probable responsive individuals. The known pathogenic variant p.R169P and the novel variant p. Leu72_Asp75delinsTyr were first classified as responsive.Seven genotypes were reported as responsive for the first time. All patients carrying at least one pathogenic variant, which was previously reported as BH4 responsive, respond to BH4. Three patients with p.L48S, p.R261Q and p.A309V pathogenic variants were exceptions. There was no certain statistical correlation between genotype and response. Genotype and phenotype were significantly correlated and majority of patients with mild phenotype carried at least one non-null pathogenic variant. In Khorasan-Razavi province of Iran, patients with at least one non-null mutation are most probable to demonstrate mild phenotype and respond to BH4 phenotype.
Collapse
Affiliation(s)
- Faeze Khaghani
- Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran; Medical Genetics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Peyman Eshraghi
- Department of Pediatric and Endocrinology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Tayebeh Hamzehloei
- Medical Genetics Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; Metabolic Syndrome Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
| |
Collapse
|
8
|
Elhawary NA, AlJahdali IA, Abumansour IS, Elhawary EN, Gaboon N, Dandini M, Madkhali A, Alosaimi W, Alzahrani A, Aljohani F, Melibary EM, Kensara OA. Genetic etiology and clinical challenges of phenylketonuria. Hum Genomics 2022; 16:22. [PMID: 35854334 PMCID: PMC9295449 DOI: 10.1186/s40246-022-00398-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 07/08/2022] [Indexed: 02/08/2023] Open
Abstract
This review discusses the epidemiology, pathophysiology, genetic etiology, and management of phenylketonuria (PKU). PKU, an autosomal recessive disease, is an inborn error of phenylalanine (Phe) metabolism caused by pathogenic variants in the phenylalanine hydroxylase (PAH) gene. The prevalence of PKU varies widely among ethnicities and geographic regions, affecting approximately 1 in 24,000 individuals worldwide. Deficiency in the PAH enzyme or, in rare cases, the cofactor tetrahydrobiopterin results in high blood Phe concentrations, causing brain dysfunction. Untreated PKU, also known as PAH deficiency, results in severe and irreversible intellectual disability, epilepsy, behavioral disorders, and clinical features such as acquired microcephaly, seizures, psychological signs, and generalized hypopigmentation of skin (including hair and eyes). Severe phenotypes are classic PKU, and less severe forms of PAH deficiency are moderate PKU, mild PKU, mild hyperphenylalaninaemia (HPA), or benign HPA. Early diagnosis and intervention must start shortly after birth to prevent major cognitive and neurological effects. Dietary treatment, including natural protein restriction and Phe-free supplements, must be used to maintain blood Phe concentrations of 120-360 μmol/L throughout the life span. Additional treatments include the casein glycomacropeptide (GMP), which contains very limited aromatic amino acids and may improve immunological function, and large neutral amino acid (LNAA) supplementation to prevent plasma Phe transport into the brain. The synthetic BH4 analog, sapropterin hydrochloride (i.e., Kuvan®, BioMarin), is another potential treatment that activates residual PAH, thus decreasing Phe concentrations in the blood of PKU patients. Moreover, daily subcutaneous injection of pegylated Phe ammonia-lyase (i.e., pegvaliase; PALYNZIQ®, BioMarin) has promised gene therapy in recent clinical trials, and mRNA approaches are also being studied.
Collapse
Affiliation(s)
- Nasser A. Elhawary
- grid.412832.e0000 0000 9137 6644Department of Medical Genetics, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Imad A. AlJahdali
- grid.412832.e0000 0000 9137 6644Department of Community Medicine, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Iman S. Abumansour
- grid.412832.e0000 0000 9137 6644Department of Medical Genetics, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Ezzeldin N. Elhawary
- grid.123047.30000000103590315Faculty of Medicine, MS Genomic Medicine Program, University of Southampton, Southampton General Hospital, Southampton, UK
| | - Nagwa Gaboon
- grid.7269.a0000 0004 0621 1570Department of Clinical Genetics, Faculty of Medicine, Ain Shams University, Cairo, Egypt
| | - Mohammed Dandini
- Department of Laboratory and Blood Bank, Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Abdulelah Madkhali
- grid.415254.30000 0004 1790 7311Department of Pathology and Laboratory Medicine, King Abdulaziz Medical City, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
| | - Wafaa Alosaimi
- Department of Hematology, Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Abdulmajeed Alzahrani
- Department of Laboratory and Blood Bank at Maternity and Children Hospital, Mecca, Saudi Arabia
| | - Fawzia Aljohani
- Department of Pediatric Clinics, Maternity and Children Hospital, King Salman Medical City, Madinah, Saudi Arabia
| | - Ehab M. Melibary
- grid.412832.e0000 0000 9137 6644Department of Medical Genetics, College of Medicine, Umm Al-Qura University, P.O. Box 57543, Mecca, 21955 Saudi Arabia
| | - Osama A. Kensara
- grid.412832.e0000 0000 9137 6644Department of Clinical Nutrition, Faculty of Applied Medical Sciences, Umm Al-Qura University, Jeddah, Saudi Arabia
- Department of Biochemistry, Batterjee Medical College, Jeddah, Saudi Arabia
| |
Collapse
|
9
|
Longo C, Montioli R, Bisello G, Palazzi L, Mastrangelo M, Brennenstuhl H, de Laureto PP, Opladen T, Leuzzi V, Bertoldi M. Compound heterozygosis in AADC deficiency: A complex phenotype dissected through comparison among heterodimeric and homodimeric AADC proteins. Mol Genet Metab 2021; 134:147-155. [PMID: 34479793 DOI: 10.1016/j.ymgme.2021.08.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 10/20/2022]
Abstract
Compound heterozygosis is the most diffuse and hardly to tackle condition in aromatic amino acid decarboxylase (AADC) deficiency, a genetic disease leading to severe neurological impairment. Here, by using an appropriate vector, we succeeded in obtaining high yields of AADC protein and characterizing two new heterodimers, T69M/S147R and C281W/M362T, detected in two AADC deficiency patients. We performed an extensive biochemical characterization of the heterodimeric recombinant proteins and of the related homodimers, by a combination of dichroic and fluorescence spectroscopy and activity assays together with bioinformatic analyses. We found that T69M/S147R exhibits negative complementation in terms of activity but it is more stable than the average of the homodimeric counterparts. The heterodimer C281W/M362T retains a nearly good catalytic efficiency, whereas M362T homodimer is less affected and C281W homodimer is recovered as insoluble. These results, which are consistent with the related phenotypes, and the data emerging from previous studies, suggest that the severity of AADC deficiency is not directly explained by positive or negative complementation phenomena, but rather depends on: i) the integrity of one or both active sites; ii) the structural and functional properties of the entire pool of AADC proteins expressed. Overall, this integrated and cross-sectional approach enables proper characterization and depicts the functional result of subunit interactions in the dimeric structure and will help to elucidate the physio-pathological mechanisms in AADC deficiency.
Collapse
Affiliation(s)
- Carmen Longo
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biological Chemistry, Strada Le Grazie 8, 37134 Verona, Italy
| | - Riccardo Montioli
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biological Chemistry, Strada Le Grazie 8, 37134 Verona, Italy
| | - Giovanni Bisello
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biological Chemistry, Strada Le Grazie 8, 37134 Verona, Italy
| | - Luana Palazzi
- Department of Pharmaceutical and Pharmacological Sciences, CRIBI Biotechnology Center, University of Padua, Padua, Italy
| | - Mario Mastrangelo
- Unit of Child Neurology and Psychiatry Unit, Department of Human Neuroscience, Sapienza University of Rome, Italy
| | - Heiko Brennenstuhl
- University Children's Hospital Heidelberg, Department of General Pediatrics, Division of Neuropediatrics and Metabolic Medicine, Heidelberg, Germany
| | - Patrizia Polverino de Laureto
- Department of Pharmaceutical and Pharmacological Sciences, CRIBI Biotechnology Center, University of Padua, Padua, Italy
| | - Thomas Opladen
- University Children's Hospital Heidelberg, Department of General Pediatrics, Division of Neuropediatrics and Metabolic Medicine, Heidelberg, Germany
| | - Vincenzo Leuzzi
- Unit of Child Neurology and Psychiatry Unit, Department of Human Neuroscience, Sapienza University of Rome, Italy
| | - Mariarita Bertoldi
- Department of Neuroscience, Biomedicine and Movement Sciences, Section of Biological Chemistry, Strada Le Grazie 8, 37134 Verona, Italy.
| |
Collapse
|
10
|
Mikó Á, Kaposi A, Schnabel K, Seidl D, Tory K. Identification of incompletely penetrant variants and interallelic interactions in autosomal recessive disorders by a population-genetic approach. Hum Mutat 2021; 42:1473-1487. [PMID: 34405919 DOI: 10.1002/humu.24273] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Revised: 07/30/2021] [Accepted: 08/15/2021] [Indexed: 01/11/2023]
Abstract
We aimed to identify incompletely penetrant (IP) variants and interallelic interactions in autosomal recessive disorders by a population-genetic approach. Genotype and clinical data were collected from 9038 patients of European origin with ASL, ATP7B, CAPN3, CFTR, CTNS, DHCR7, GAA, GALNS, GALT, IDUA, MUT, NPHS1, NPHS2, PAH, PKHD1, PMM2, or SLC26A4-related disorders. We calculated the relative allele frequency of each pathogenic variant (n = 1936) to the loss-of-function (LOF) variants of the corresponding gene in the patient ( A C p t V / A C p t L O F ) and the general population ( AC gnomAD V / AC gnomAD LOF ) and estimated the penetrance of each variant by calculating their ratio: ( A C p t V / A C p t L O F ) ( A C g n o m A D V / A C g n o m A D L O F ) (V/LOF ratio). We classified all variants as null or hypomorphic based on the associated clinical phenotype. We found 25 variants, 29% of the frequent 85 variants, to be underrepresented in the patient population (V/LOF ratio <30% with p < 7.22 × 10-5 ), including 22 novel ones in the ASL, CAPN3, CFTR, GAA, GALNS, PAH, and PKHD1 genes. In contrast to the completely penetrant variants (CP), the majority of the IP variants were hypomorphic (IP: 16/18, 88%; CP: 177/933, 19.0%; p = 5.12 × 10-10 ). Among them, only the NPHS2 R229Q variant was subject to interallelic interactions. The proposed algorithm identifies frequent IP variants and estimates their penetrance and interallelic interactions in large patient cohorts.
Collapse
Affiliation(s)
- Ágnes Mikó
- MTA-SE Lendület Nephrogenetic Laboratory, Hungarian Academy of Sciences, Budapest, Hungary.,1st Department of Pediatrics, Semmelweis University, Budapest, Hungary
| | - Ambrus Kaposi
- MTA-SE Lendület Nephrogenetic Laboratory, Hungarian Academy of Sciences, Budapest, Hungary.,Department of Programming Languages and Compilers, Faculty of Informatics, Eötvös Loránd University, Budapest, Hungary
| | - Karolina Schnabel
- MTA-SE Lendület Nephrogenetic Laboratory, Hungarian Academy of Sciences, Budapest, Hungary.,1st Department of Pediatrics, Semmelweis University, Budapest, Hungary
| | - Dániel Seidl
- MTA-SE Lendület Nephrogenetic Laboratory, Hungarian Academy of Sciences, Budapest, Hungary.,1st Department of Pediatrics, Semmelweis University, Budapest, Hungary
| | - Kálmán Tory
- MTA-SE Lendület Nephrogenetic Laboratory, Hungarian Academy of Sciences, Budapest, Hungary.,1st Department of Pediatrics, Semmelweis University, Budapest, Hungary
| |
Collapse
|
11
|
Abstract
Phenylketonuria (PKU; also known as phenylalanine hydroxylase (PAH) deficiency) is an autosomal recessive disorder of phenylalanine metabolism, in which especially high phenylalanine concentrations cause brain dysfunction. If untreated, this brain dysfunction results in severe intellectual disability, epilepsy and behavioural problems. The prevalence varies worldwide, with an average of about 1:10,000 newborns. Early diagnosis is based on newborn screening, and if treatment is started early and continued, intelligence is within normal limits with, on average, some suboptimal neurocognitive function. Dietary restriction of phenylalanine has been the mainstay of treatment for over 60 years and has been highly successful, although outcomes are still suboptimal and patients can find the treatment difficult to adhere to. Pharmacological treatments are available, such as tetrahydrobiopterin, which is effective in only a minority of patients (usually those with milder PKU), and pegylated phenylalanine ammonia lyase, which requires daily subcutaneous injections and causes adverse immune responses. Given the drawbacks of these approaches, other treatments are in development, such as mRNA and gene therapy. Even though PAH deficiency is the most common defect of amino acid metabolism in humans, brain dysfunction in individuals with PKU is still not well understood and further research is needed to facilitate development of pathophysiology-driven treatments.
Collapse
Affiliation(s)
- Francjan J van Spronsen
- Beatrix Children's Hospital, University Medical Centre Groningen, University of Groningen, Groningen, Netherlands.
| | - Nenad Blau
- University Children's Hospital in Zurich, Zurich, Switzerland
| | - Cary Harding
- Department of Molecular and Medical Genetics and Department of Pediatrics, Oregon Health & Science University, Oregon, USA
| | | | - Nicola Longo
- Department of Pediatrics, University of Utah, Salt Lake City, Utah, USA
| | - Annet M Bosch
- University of Amsterdam, Department of Pediatrics, Division of Metabolic Disorders, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands
| |
Collapse
|
12
|
Aslan T, Yenenler-Kutlu A, Gerlevik U, Aktuğlu Zeybek AÇ, Kıykım E, Sezerman OU, Birgul Iyison N. Identifying and elucidating the roles of Y198N and Y204F mutations in the PAH enzyme through molecular dynamic simulations. J Biomol Struct Dyn 2021; 40:9018-9029. [PMID: 33970801 DOI: 10.1080/07391102.2021.1921619] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Phenylketonuria is an autosomal recessive disorder caused by mutations in the phenylalanine hydroxylase gene. In phenylketonuria causes various symptoms including severe mental retardation. PAH gene of a classical Phenylketonuria patient was sequenced, and two novel heterozygous mutations, p.Y198N and p.Y204F, were found. This study aimed to reveal the impacts of these variants on the structural stability of the PAH enzyme. In-silico analyses using prediction tools and molecular dynamics simulations were performed. Mutations were introduced to the wild type catalytic monomer and full length tetramer crystal structures. Variant pathogenicity analyses predicted p.Y198N to be damaging, and p.Y204F to be benign by some prediction tools and damaging by others. Simulations suggested p.Y198N mutation cause significant fluctuations in the spatial organization of two catalytic residues in the temperature accelerated MD simulations with the monomer and increased root-mean-square deviations in the tetramer structure. p.Y204F causes noticeable changes in the spatial positioning of T278 suggesting a possible segregation from the catalytic site in temperature accelerated MD simulations with the monomer. This mutation also leads to increased root-mean-square fluctuations in the regulatory domain which may lead to conformational change resulting in inhibition of dimerization and enzyme activation. Our study reports two novel mutations in the PAH gene and gives insight to their effects on the PAH activity. MD simulations did not yield conclusive results that explains the phenotype but gave plausible insight to possible effects which should be investigated further with in-silico and in-vitro studies to assess the roles of these mutations in etiology of PKU. Communicated by Ramaswamy H. Sarma.
Collapse
Affiliation(s)
- Tolga Aslan
- Faculty of Arts and Sciences, Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkey
| | - Aslı Yenenler-Kutlu
- Department of Biostatistics and Medical Informatics, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey.,Faculty of Science and Literature, Department of Molecular Biology & Genetics, Istinye University, Istanbul, Turkey
| | - Umut Gerlevik
- Department of Biostatistics and Medical Informatics, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Ayşe Çiğdem Aktuğlu Zeybek
- Cerrahpasa Faculty of Medicine, Divisions of Nutrition and Metabolism, Department of Pediatrics, Istanbul University, İstanbul, Turkey
| | - Ertuğrul Kıykım
- Cerrahpasa Faculty of Medicine, Divisions of Nutrition and Metabolism, Department of Pediatrics, Istanbul University, İstanbul, Turkey
| | - Osman Uğur Sezerman
- Department of Biostatistics and Medical Informatics, School of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Necla Birgul Iyison
- Faculty of Arts and Sciences, Department of Molecular Biology and Genetics, Bogazici University, Istanbul, Turkey
| |
Collapse
|
13
|
Hillert A, Anikster Y, Belanger-Quintana A, Burlina A, Burton BK, Carducci C, Chiesa AE, Christodoulou J, Đorđević M, Desviat LR, Eliyahu A, Evers RAF, Fajkusova L, Feillet F, Bonfim-Freitas PE, Giżewska M, Gundorova P, Karall D, Kneller K, Kutsev SI, Leuzzi V, Levy HL, Lichter-Konecki U, Muntau AC, Namour F, Oltarzewski M, Paras A, Perez B, Polak E, Polyakov AV, Porta F, Rohrbach M, Scholl-Bürgi S, Spécola N, Stojiljković M, Shen N, Santana-da Silva LC, Skouma A, van Spronsen F, Stoppioni V, Thöny B, Trefz FK, Vockley J, Yu Y, Zschocke J, Hoffmann GF, Garbade SF, Blau N. The Genetic Landscape and Epidemiology of Phenylketonuria. Am J Hum Genet 2020; 107:234-250. [PMID: 32668217 PMCID: PMC7413859 DOI: 10.1016/j.ajhg.2020.06.006] [Citation(s) in RCA: 121] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 06/05/2020] [Indexed: 11/22/2022] Open
Abstract
Phenylketonuria (PKU), caused by variants in the phenylalanine hydroxylase (PAH) gene, is the most common autosomal-recessive Mendelian phenotype of amino acid metabolism. We estimated that globally 0.45 million individuals have PKU, with global prevalence 1:23,930 live births (range 1:4,500 [Italy]-1:125,000 [Japan]). Comparing genotypes and metabolic phenotypes from 16,092 affected subjects revealed differences in disease severity in 51 countries from 17 world regions, with the global phenotype distribution of 62% classic PKU, 22% mild PKU, and 16% mild hyperphenylalaninemia. A gradient in genotype and phenotype distribution exists across Europe, from classic PKU in the east to mild PKU in the southwest and mild hyperphenylalaninemia in the south. The c.1241A>G (p.Tyr414Cys)-associated genotype can be traced from Northern to Western Europe, from Sweden via Norway, to Denmark, to the Netherlands. The frequency of classic PKU increases from Europe (56%) via Middle East (71%) to Australia (80%). Of 758 PAH variants, c.1222C>T (p.Arg408Trp) (22.2%), c.1066-11G>A (IVS10-11G>A) (6.4%), and c.782G>A (p.Arg261Gln) (5.5%) were most common and responsible for two prevalent genotypes: p.[Arg408Trp];[Arg408Trp] (11.4%) and c.[1066-11G>A];[1066-11G>A] (2.6%). Most genotypes (73%) were compound heterozygous, 27% were homozygous, and 55% of 3,659 different genotypes occurred in only a single individual. PAH variants were scored using an allelic phenotype value and correlated with pre-treatment blood phenylalanine concentrations (n = 6,115) and tetrahydrobiopterin loading test results (n = 4,381), enabling prediction of both a genotype-based phenotype (88%) and tetrahydrobiopterin responsiveness (83%). This study shows that large genotype databases enable accurate phenotype prediction, allowing appropriate targeting of therapies to optimize clinical outcome.
Collapse
Affiliation(s)
- Alicia Hillert
- Division of Child Neurology and Metabolic Medicine, Centre for Child and Adolescent Medicine, Clinic I, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Yair Anikster
- Metabolic Disease Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Aviv University, 52621 Tel-Aviv, Israel
| | - Amaya Belanger-Quintana
- Unidad de Enfermedades Metabolicas, Servicio de Pediatria, Hospital Ramon y Cajal, 28034 Madrid, Spain
| | - Alberto Burlina
- Division of Inherited Metabolic Diseases, Department of Woman's and Child's Health, University Hospital, 35129 Padua, Italy
| | - Barbara K Burton
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL 60611, USA
| | - Carla Carducci
- Department of Experimental Medicine, Sapienza University of Rome, 00185 Rome, Italy
| | - Ana E Chiesa
- Fundación de Endocrinología Infantil (FEI), C1425 Buenos Aires, Argentina
| | - John Christodoulou
- Murdoch Children's Research Institute and Department of Pediatrics, University of Melbourne, Melbourne, VIC 3052, Australia
| | - Maja Đorđević
- Institute of Mother and Child Healthcare "Dr. Vukan Čupić," 11000 Belgrade, Serbia
| | - Lourdes R Desviat
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular CSIC-UAM, Universidad Autónoma de Madrid. CIBERER, IdiPAz, 28049 Madrid, Spain
| | - Aviva Eliyahu
- Metabolic Disease Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Aviv University, 52621 Tel-Aviv, Israel
| | - Roeland A F Evers
- University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Section of Metabolic Diseases, 9712 CP Groningen, the Netherlands
| | - Lena Fajkusova
- Centre of Molecular Biology and Gene Therapy, University Hospital Brno, 62500 Brno, Czech Republic
| | - François Feillet
- Reference Center for Inherited Metabolic Diseases, University Hospital of Nancy, 54511 Vandoeuvre-lès-Nancy, France
| | - Pedro E Bonfim-Freitas
- Laboratory of Inborn Errors of Metabolism, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, Brazil
| | - Maria Giżewska
- Department of Pediatrics, Endocrinology, Diabetology, Metabolic Diseases and Cardiology, Pomeranian Medical University, 71-252 Szczecin, Poland
| | | | - Daniela Karall
- Clinic of Pediatrics, Division of Inherited Metabolic Disorders, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Katya Kneller
- Metabolic Disease Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Tel-Aviv University, 52621 Tel-Aviv, Israel
| | | | - Vincenzo Leuzzi
- Department of Human Neuroscience, Sapienza University of Rome, 00185 Rome, Italy
| | - Harvey L Levy
- Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | | | - Ania C Muntau
- University Children's Hospital, University Medical Center Hamburg Eppendorf, 20246 Hamburg, Germany
| | - Fares Namour
- Reference Center for Inherited Metabolic Diseases, University Hospital of Nancy, 54511 Vandoeuvre-lès-Nancy, France
| | - Mariusz Oltarzewski
- Department of Screening and Metabolic Diagnostics, Institute of Mother and Child, 01-211 Warsaw, Poland
| | - Andrea Paras
- Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL 60611, USA
| | - Belen Perez
- Centro de Diagnóstico de Enfermedades Moleculares, Centro de Biología Molecular CSIC-UAM, Universidad Autónoma de Madrid. CIBERER, IdiPAz, 28049 Madrid, Spain
| | - Emil Polak
- Comenius University, Faculty of Natural Sciences, Department of Molecular Biology, 84215 Bratislava 4, Slovak Republic
| | | | - Francesco Porta
- Department of Pediatrics, AOU Citta' della Salute e della Scienza di Torino, 10126 Torino, Italy
| | - Marianne Rohrbach
- Division of Metabolism, University Children's Hospital, 8032 Zürich, Switzerland
| | - Sabine Scholl-Bürgi
- Clinic of Pediatrics, Division of Inherited Metabolic Disorders, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Norma Spécola
- Unidad de Metabolismo. Hospital de Niños "Sor Ludovica" de La Plata, 1904 Buenos Aires, Argentina
| | - Maja Stojiljković
- Institute of Molecular Genetics and Genetic Engineering, University of Belgrade, 11000 Belgrade, Serbia
| | - Nan Shen
- Department of Infectious Diseases, Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, 2000025 Shanghai, China
| | - Luiz C Santana-da Silva
- Laboratory of Inborn Errors of Metabolism, Institute of Biological Sciences, Federal University of Pará, Belém 66075-110, Brazil
| | | | - Francjan van Spronsen
- University of Groningen, University Medical Center Groningen, Beatrix Children's Hospital, Section of Metabolic Diseases, 9712 CP Groningen, the Netherlands
| | - Vera Stoppioni
- Centro Screening Neonatale Regione Marche, Azienda Ospedaliera Ospedali Riuniti Marche Nord, 61032 Fano, Italy
| | - Beat Thöny
- Division of Metabolism, University Children's Hospital, 8032 Zürich, Switzerland
| | - Friedrich K Trefz
- Division of Child Neurology and Metabolic Medicine, Centre for Child and Adolescent Medicine, Clinic I, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Jerry Vockley
- UPMC, Children's Hospital of Pittsburgh, Pittsburgh, PA 15224, USA
| | - Youngguo Yu
- Department of Pediatric Endocrinology/Genetics, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Institute for Pediatric Research, 2000025 Shanghai, China
| | - Johannes Zschocke
- Institute of Human Genetics, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Georg F Hoffmann
- Division of Child Neurology and Metabolic Medicine, Centre for Child and Adolescent Medicine, Clinic I, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Sven F Garbade
- Division of Child Neurology and Metabolic Medicine, Centre for Child and Adolescent Medicine, Clinic I, University Hospital Heidelberg, 69120 Heidelberg, Germany.
| | - Nenad Blau
- Division of Child Neurology and Metabolic Medicine, Centre for Child and Adolescent Medicine, Clinic I, University Hospital Heidelberg, 69120 Heidelberg, Germany; Division of Metabolism, University Children's Hospital, 8032 Zürich, Switzerland.
| |
Collapse
|
14
|
Sarodaya N, Suresh B, Kim KS, Ramakrishna S. Protein Degradation and the Pathologic Basis of Phenylketonuria and Hereditary Tyrosinemia. Int J Mol Sci 2020; 21:ijms21144996. [PMID: 32679806 PMCID: PMC7404301 DOI: 10.3390/ijms21144996] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 07/10/2020] [Accepted: 07/13/2020] [Indexed: 12/15/2022] Open
Abstract
A delicate intracellular balance among protein synthesis, folding, and degradation is essential to maintaining protein homeostasis or proteostasis, and it is challenged by genetic and environmental factors. Molecular chaperones and the ubiquitin proteasome system (UPS) play a vital role in proteostasis for normal cellular function. As part of protein quality control, molecular chaperones recognize misfolded proteins and assist in their refolding. Proteins that are beyond repair or refolding undergo degradation, which is largely mediated by the UPS. The importance of protein quality control is becoming ever clearer, but it can also be a disease-causing mechanism. Diseases such as phenylketonuria (PKU) and hereditary tyrosinemia-I (HT1) are caused due to mutations in PAH and FAH gene, resulting in reduced protein stability, misfolding, accelerated degradation, and deficiency in functional proteins. Misfolded or partially unfolded proteins do not necessarily lose their functional activity completely. Thus, partially functional proteins can be rescued from degradation by molecular chaperones and deubiquitinating enzymes (DUBs). Deubiquitination is an important mechanism of the UPS that can reverse the degradation of a substrate protein by covalently removing its attached ubiquitin molecule. In this review, we discuss the importance of molecular chaperones and DUBs in reducing the severity of PKU and HT1 by stabilizing and rescuing mutant proteins.
Collapse
Affiliation(s)
- Neha Sarodaya
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (N.S.); (B.S.)
| | - Bharathi Suresh
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (N.S.); (B.S.)
| | - Kye-Seong Kim
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (N.S.); (B.S.)
- College of Medicine, Hanyang University, Seoul 04763, Korea
- Correspondence: (K.-S.K.); or (S.R.)
| | - Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Korea; (N.S.); (B.S.)
- College of Medicine, Hanyang University, Seoul 04763, Korea
- Correspondence: (K.-S.K.); or (S.R.)
| |
Collapse
|
15
|
Caletti MT, Bettocchi I, Baronio F, Brodosi L, Cataldi S, Petroni ML, Cassio A, Marchesini G. Maternal PKU: Defining phenylalanine tolerance and its variation during pregnancy, according to genetic background. Nutr Metab Cardiovasc Dis 2020; 30:977-983. [PMID: 32409273 DOI: 10.1016/j.numecd.2020.02.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 02/11/2020] [Accepted: 02/12/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND AND AIMS Phenylketonuria (PKU)-affected women may become pregnant, and dietary phenylalanine (Phe) intake must be adjusted according to Phe tolerance. We report our experience with maternal PKU in relation to genotype PKU heterogeneity. METHODS AND RESULTS A total of 10 pregnancies in 7 PKU women (7 different genotypes) were followed up as part of personalized care. Phe tolerance during preconception and pregnancy was assessed by strict dietary control and weekly Phe measurement (blood spots) in relation to genotype. Most women had stopped PKU diet during childhood or adolescence and six pregnancies were unplanned; a phenylalanine-restricted diet was reinstituted soon after conception. Women were classified according to their Phe levels at birth screening and genotype. Phe tolerance increased systematically in the course of pregnancy in all cases, but the increase was different in subjects with classic PKU (cPKU) when compared with cases with mild hyperphenylalaninemia (mHPA), both on average (+297 mg/day in cPKU vs. 597 in mHPA; P = 0.017) and as percentage (+107% in cPKU vs. +17% in mHPA). Notably, Phe tolerance also varied in the same women in the course of different pregnancies, when body weight gain was also different. Two newborns from the same cPKU mother (unplanned pregnancies on free diet) were affected by congenital alterations. CONCLUSIONS Several factors influence metabolic phenotype in maternal PKU, to an unpredictable extent even in the same woman. The number of maternal PKU cases is growing in dedicated Nutrition Units, and the burden associated with careful management of this condition for the health care system should be adequately considered.
Collapse
Affiliation(s)
- Maria T Caletti
- Unit of Metabolic Diseases and Clinical Dietetics - DIMEC, "Alma Mater" University, Bologna, Italy
| | - Ilaria Bettocchi
- Unit of Pediatrics - DIMEC, "Alma Mater" University, Bologna, Italy
| | - Federico Baronio
- Unit of Pediatrics - DIMEC, "Alma Mater" University, Bologna, Italy
| | - Lucia Brodosi
- Unit of Metabolic Diseases and Clinical Dietetics - DIMEC, "Alma Mater" University, Bologna, Italy
| | - Sara Cataldi
- Unit of Metabolic Diseases and Clinical Dietetics - DIMEC, "Alma Mater" University, Bologna, Italy
| | - Maria L Petroni
- Unit of Metabolic Diseases and Clinical Dietetics - DIMEC, "Alma Mater" University, Bologna, Italy
| | | | - Giulio Marchesini
- Unit of Metabolic Diseases and Clinical Dietetics - DIMEC, "Alma Mater" University, Bologna, Italy.
| |
Collapse
|
16
|
Rajabi F, Rohr F, Wessel A, Martell L, Dobrowolski SF, Guldberg P, Güttler F, Levy HL. Phenylalanine hydroxylase genotype-phenotype associations in the United States: A single center study. Mol Genet Metab 2019; 128:415-421. [PMID: 31623983 DOI: 10.1016/j.ymgme.2019.09.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 09/12/2019] [Accepted: 09/13/2019] [Indexed: 11/28/2022]
Abstract
Phenylketonuria (PKU) is an autosomal recessive inborn error of metabolism caused by pathogenic variants in the phenylalanine hydroxylase gene (PAH). The correlation between genotype and phenotype can be complex and sometimes variable but often very useful for categorizing and predicting dietary tolerance and potential outcome. We reviewed medical records for 367 patients diagnosed with PKU or persistent mild hyperphenylalaninemia (MHP) between 1950 and 2015 who had PAH genotyping. In 351 we had the full PAH genotype as well as phenotypic characteristics such as phenylalanine (Phe) concentrations (at newborn screening, confirmation, and highest known), and dietary Phe tolerance. On 716 mutant chromosomes, including 14 in genotypes with only one identified variant, we identified 114 different pathogenic variants. The most frequent, p.R408W, was present in 15.4% of the alleles; other frequent variants were c.1315 + 1G > A (6.1%), p.I65T (5.7%), and p.R261Q (5.7%). Three variants, c.142 T > G (p.L48 V), c.615G > C (p.E205D), and c.1342_1345delCTCC, were novel. We used the phenotypic parameters of variants paired with null alleles (functional hemizygotes) to assign the variants as classic PKU, moderate PKU, mild PKU, MHP-gray zone, or MHP. We also included the phenotype association(s) for all of the full genotypes. In 103 patients, we also could assign sapropterin dihydrochloride responsiveness, which is a synthetic form of the tetrahydrobiopterin (BH4) PAH cofactor. This compilation from a single metabolic center provides further information on PAH variants in the United States and the correlations between genotype and phenotype.
Collapse
Affiliation(s)
- Farrah Rajabi
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - Frances Rohr
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - Ann Wessel
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - Leslie Martell
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | | | - Per Guldberg
- Danish Cancer Society Research Center, Copenhagen, Denmark
| | | | - Harvey L Levy
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA; Department of Pediatrics, Harvard Medical School, Boston, MA, USA.
| |
Collapse
|
17
|
Zastrow DB, Baudet H, Shen W, Thomas A, Si Y, Weaver MA, Lager AM, Liu J, Mangels R, Dwight SS, Wright MW, Dobrowolski SF, Eilbeck K, Enns GM, Feigenbaum A, Lichter-Konecki U, Lyon E, Pasquali M, Watson M, Blau N, Steiner RD, Craigen WJ, Mao R. Unique aspects of sequence variant interpretation for inborn errors of metabolism (IEM): The ClinGen IEM Working Group and the Phenylalanine Hydroxylase Gene. Hum Mutat 2019; 39:1569-1580. [PMID: 30311390 DOI: 10.1002/humu.23649] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 08/28/2018] [Accepted: 09/06/2018] [Indexed: 11/09/2022]
Abstract
The ClinGen Inborn Errors of Metabolism Working Group was tasked with creating a comprehensive, standardized knowledge base of genes and variants for metabolic diseases. Phenylalanine hydroxylase (PAH) deficiency was chosen to pilot development of the Working Group's standards and guidelines. A PAH variant curation expert panel (VCEP) was created to facilitate this process. Following ACMG-AMP variant interpretation guidelines, we present the development of these standards in the context of PAH variant curation and interpretation. Existing ACMG-AMP rules were adjusted based on disease (6) or strength (5) or both (2). Disease adjustments include allele frequency thresholds, functional assay thresholds, and phenotype-specific guidelines. Our validation of PAH-specific variant interpretation guidelines is presented using 85 variants. The PAH VCEP interpretations were concordant with existing interpretations in ClinVar for 69 variants (81%). Development of biocurator tools and standards are also described. Using the PAH-specific ACMG-AMP guidelines, 714 PAH variants have been curated and will be submitted to ClinVar. We also discuss strategies and challenges in applying ACMG-AMP guidelines to autosomal recessive metabolic disease, and the curation of variants in these genes.
Collapse
Affiliation(s)
- Diane B Zastrow
- Palo Alto Medical Foundation, Palo Alto, California.,Stanford University, Stanford, California
| | - Heather Baudet
- University of North Carolina, Chapel Hill, North Carolina
| | - Wei Shen
- ARUP Laboratories, Salt Lake City, Utah.,University of Utah, Salt Lake City, Utah
| | - Amanda Thomas
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, New York
| | - Yue Si
- GeneDx, Gaithersburg, Maryland
| | - Meredith A Weaver
- American College of Medical Genetics and Genomics, Bethesda, Maryland
| | - Angela M Lager
- Section of Hematology/Oncology, Department of Medicine, University of Chicago, Chicago, Illinois
| | - Jixia Liu
- Marshfield Clinic Research Institute, Marshfield, Wisconsin
| | | | | | | | | | | | | | - Annette Feigenbaum
- Rady Children's Hospital and University of California, San Diego, California
| | - Uta Lichter-Konecki
- Children's Hospital of Pittsburg of UPMC, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Elaine Lyon
- ARUP Laboratories, Salt Lake City, Utah.,University of Utah, Salt Lake City, Utah
| | - Marzia Pasquali
- ARUP Laboratories, Salt Lake City, Utah.,University of Utah, Salt Lake City, Utah
| | - Michael Watson
- American College of Medical Genetics and Genomics, Bethesda, Maryland
| | - Nenad Blau
- Dietmar-Hopp Metabolic Center, University Children's Hospital, Department of General Pediatrics, Heidelberg, Germany
| | - Robert D Steiner
- Marshfield Clinic Research Institute, Marshfield, Wisconsin.,University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | | | - Rong Mao
- ARUP Laboratories, Salt Lake City, Utah.,University of Utah, Salt Lake City, Utah
| | | |
Collapse
|
18
|
Arturo EC, Gupta K, Hansen MR, Borne E, Jaffe EK. Biophysical characterization of full-length human phenylalanine hydroxylase provides a deeper understanding of its quaternary structure equilibrium. J Biol Chem 2019; 294:10131-10145. [PMID: 31076506 PMCID: PMC6664189 DOI: 10.1074/jbc.ra119.008294] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 05/09/2019] [Indexed: 11/06/2022] Open
Abstract
Dysfunction of human phenylalanine hydroxylase (hPAH, EC 1.14.16.1) is the primary cause of phenylketonuria, the most common inborn error of amino acid metabolism. The dynamic domain rearrangements of this multimeric protein have thwarted structural study of the full-length form for decades, until now. In this study, a tractable C29S variant of hPAH (C29S) yielded a 3.06 Å resolution crystal structure of the tetrameric resting-state conformation. We used size-exclusion chromatography in line with small-angle X-ray scattering (SEC-SAXS) to analyze the full-length hPAH solution structure both in the presence and absence of Phe, which serves as both substrate and allosteric activators. Allosteric Phe binding favors accumulation of an activated PAH tetramer conformation, which is biophysically distinct in solution. Protein characterization with enzyme kinetics and intrinsic fluorescence revealed that the C29S variant and hPAH are otherwise equivalent in their response to Phe, further supported by their behavior on various chromatography resins and by analytical ultracentrifugation. Modeling of resting-state and activated forms of C29S against SAXS data with available structural data created and evaluated several new models for the transition between the architecturally distinct conformations of PAH and highlighted unique intra- and inter-subunit interactions. Three best-fitting alternative models all placed the allosteric Phe-binding module 8-10 Å farther from the tetramer center than do all previous models. The structural insights into allosteric activation of hPAH reported here may help inform ongoing efforts to treat phenylketonuria with novel therapeutic approaches.
Collapse
Affiliation(s)
- Emilia C Arturo
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111
- the Department of Biochemistry and Molecular Biology, Drexel University College of Medicine, Philadelphia, Pennsylvania 19102, and
| | - Kushol Gupta
- the Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Michael R Hansen
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111
| | - Elias Borne
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111
| | - Eileen K Jaffe
- From the Molecular Therapeutics Program, Fox Chase Cancer Center, Temple University Health Systems, Philadelphia, Pennsylvania 19111,
| |
Collapse
|
19
|
Pecimonova M, Kluckova D, Csicsay F, Reblova K, Krahulec J, Procházkova D, Skultety L, Kadasi L, Soltysova A. Structural and Functional Impact of Seven Missense Variants of Phenylalanine Hydroxylase. Genes (Basel) 2019; 10:E459. [PMID: 31208052 PMCID: PMC6628251 DOI: 10.3390/genes10060459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 06/12/2019] [Accepted: 06/13/2019] [Indexed: 11/17/2022] Open
Abstract
The molecular genetics of well-characterized inherited diseases, such as phenylketonuria (PKU) and hyperphenylalaninemia (HPA) predominantly caused by mutations in the phenylalanine hydroxylase (PAH) gene, is often complicated by the identification of many novel variants, often with no obvious impact on the associated disorder. To date, more than 1100 PAH variants have been identified of which a substantial portion have unknown clinical significance. In this work, we study the functionality of seven yet uncharacterized PAH missense variants p.Asn167Tyr, p.Thr200Asn, p.Asp229Gly, p.Gly239Ala, p.Phe263Ser, p.Ala342Pro, and p.Ile406Met first identified in the Czech PKU/HPA patients. From all tested variants, three of them, namely p.Asn167Tyr, p.Thr200Asn, and p.Ile406Met, exerted residual enzymatic activity in vitro similar to wild type (WT) PAH, however, when expressed in HepG2 cells, their protein level reached a maximum of 72.1% ± 4.9%, 11.2% ± 4.2%, and 36.6% ± 7.3% compared to WT PAH, respectively. Remaining variants were null with no enzyme activity and decreased protein levels in HepG2 cells. The chaperone-like effect of applied BH4 precursor increased protein level significantly for p.Asn167Tyr, p.Asp229Gly, p.Ala342Pro, and p.Ile406Met. Taken together, our results of functional characterization in combination with in silico prediction suggest that while p.Asn167Tyr, p.Thr200Asn, and p.Ile406Met PAH variants have a mild impact on the protein, p.Asp229Gly, p.Gly239Ala, p.Phe263Ser, and p.Ala342Pro severely affect protein structure and function.
Collapse
Affiliation(s)
- Martina Pecimonova
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia.
| | - Daniela Kluckova
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia.
| | - Frantisek Csicsay
- Insitute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia.
| | - Kamila Reblova
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic.
| | - Jan Krahulec
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia.
| | - Dagmar Procházkova
- Department of Pediatrics, Medical Faculty of Masaryk University and University Hospital Brno, Černopolní 9, 625 00 Brno, Czech Republic.
| | - Ludovit Skultety
- Insitute of Virology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia.
| | - Ludevit Kadasi
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia.
- Institute for Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia.
| | - Andrea Soltysova
- Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 842 15 Bratislava, Slovakia.
- Institute for Clinical and Translational Research, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, 845 05 Bratislava, Slovakia.
| |
Collapse
|
20
|
In vitro residual activities in 20 variants of phenylalanine hydroxylase and genotype-phenotype correlation in phenylketonuria patients. Gene 2019; 707:239-245. [PMID: 31102715 DOI: 10.1016/j.gene.2019.05.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 04/12/2019] [Accepted: 05/13/2019] [Indexed: 11/21/2022]
Abstract
Phenylketonuria (PKU), caused by phenylalanine hydroxylase (PAH) gene variants, is a common autosomal inherited metabolic disease. So far, 1111 PAH variants have been revealed. The residual activity of the PAH variants is the key determinant of the metabolic phenotype and BH4 responsiveness in PKU patients. In this study, the spectrum of PAH variants in 1083 Chinese PKU patients was analyzed. Then 20 variants (p.L52F, p.R86P, p.L128P, p.L142P, p.D163N, p.C203G, p.E214G, p.F260L, p.M276T, p.L311R, p.P314A, p.L364F, p.Q375H, p.F382I, p.A395S, p.V412D, p.E108*, p.C203*, p.C284* and p.E353*) were expressed in COS-7 cells. The residual activities and protein expression levels were detected by isotope-dilution liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) and Western blotting, respectively. We compared the results of the phenotypic prediction based on APV and PAH activity respectively, and further explored the relationship between residual activity and phenotype in PKU patients. We reported 9 newly discovered PAH variants for the first time, thereby expanding the spectrum of PAH variants. Among the 20 variants in our assay, 8 variants showed mild impaired residual activities (48-92%) and approximately normal protein expression levels compared to the wild-type PAH. In contrast, 9 variants showed severely impaired residual activities (0-34%) and reduced protein expression. However, three variants (p.L52F, p.F260L and p.P314A) showed impaired residual activities (5%, 32% and 29%), although the proteins were well expressed. We assigned APV scores for 14 variants, in which the results of the phenotypic prediction were consistent for 12/14 (86%) variants based on APV and residual activity respectively, and the residual activity correctly predicted 17/22 (77%) of the patients. Our study helped to further understand the genotype-phenotype correlation in PKU patients.
Collapse
|
21
|
Jung-Kc K, Himmelreich N, Prestegård KS, Shi TJS, Scherer T, Ying M, Jorge-Finnigan A, Thöny B, Blau N, Martinez A. Phenylalanine hydroxylase variants interact with the co-chaperone DNAJC12. Hum Mutat 2019; 40:483-494. [PMID: 30667134 DOI: 10.1002/humu.23712] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 01/12/2019] [Accepted: 01/19/2019] [Indexed: 12/13/2022]
Abstract
DNAJC12, a type III member of the HSP40/DNAJ family, has been identified as the specific co-chaperone of phenylalanine hydroxylase (PAH) and the other aromatic amino acid hydroxylases. DNAJ proteins work together with molecular chaperones of the HSP70 family to assist in proper folding and maintenance of intracellular stability of their clients. Autosomal recessive mutations in DNAJC12 were found to reduce PAH levels, leading to hyperphenylalaninemia (HPA) in patients without mutations in PAH. In this work, we investigated the interaction of normal wild-type DNAJC12 with mutant PAH in cells expressing several PAH variants associated with HPA in humans, as well as in the Enu1/1 mouse model, homozygous for the V106A-Pah variant, which leads to severe protein instability, accelerated PAH degradation and mild HPA. We found that mutant PAH exhibits increased ubiquitination, instability, and aggregation compared with normal PAH. In mouse liver lysates, we showed that DNAJC12 interacts with monoubiquitin-tagged PAH. This form represented a major fraction of PAH in the Enu1/1 but was also present in liver of wild-type PAH mice. Our results support a role of DNAJC12 in the processing of misfolded ubiquitinated PAH by the ubiquitin-dependent proteasome/autophagy systems and add to the evidence that the DNAJ proteins are important players both for proper folding and degradation of their clients.
Collapse
Affiliation(s)
- Kunwar Jung-Kc
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | | | | | - Tanja Scherer
- Division of Metabolism, University Children's Hospital Zürich, Zürich, Switzerland
| | - Ming Ying
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | | | - Beat Thöny
- Division of Metabolism, University Children's Hospital Zürich, Zürich, Switzerland
| | - Nenad Blau
- Dietmar-Hopp-Metabolic Center, University Children's Hospital, Heidelberg, Germany.,Division of Metabolism, University Children's Hospital Zürich, Zürich, Switzerland
| | - Aurora Martinez
- Department of Biomedicine, University of Bergen, Bergen, Norway
| |
Collapse
|
22
|
Kure S, Shintaku H. Tetrahydrobipterin-responsive phenylalanine hydroxylase deficiency. J Hum Genet 2019; 64:67-71. [PMID: 30504912 DOI: 10.1038/s10038-018-0529-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 10/16/2018] [Accepted: 10/19/2018] [Indexed: 11/08/2022]
Affiliation(s)
- Shigeo Kure
- Department of Pediatrics, Tohoku University Graduate School of Medicine, Sendai, Japan.
| | - Haruo Shintaku
- Department of Pediatrics, Osaka City University Graduate School of Medicine, Osaka, Japan
| |
Collapse
|
23
|
Radiosynthesis and Preliminary Biological Evaluation of 18F-Fluoropropionyl-Chlorotoxin as a Potential PET Tracer for Glioma Imaging. CONTRAST MEDIA & MOLECULAR IMAGING 2018; 2018:8439162. [PMID: 30670934 PMCID: PMC6317094 DOI: 10.1155/2018/8439162] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 10/15/2018] [Accepted: 10/24/2018] [Indexed: 01/15/2023]
Abstract
Purposes Chlorotoxin can specifically bind to matrix metalloproteinase 2 (MMP-2), which are overexpressed in the glioma. In this work, radiosynthesis of [18F]-fluoropropionyl-chlorotoxin ([18F]-FP-chlorotoxin) as a novel PET tracer was investigated, and biodistribution in vivo and PET imaging were performed in the C6 glioma model. Procedures [18F]-FP-chlorotoxin was prepared from the reaction of chlorotoxin with [18F]-NFB (4-nitrophenyl 2-[18F]-fluoropropionate), which was synthesized from multistep reactions. Biodistribution was determined in 20 normal Kunming mice. Small-animal PET imaging with [18F]-FP-chlorotoxin was performed on the same rats bearing orthotopic C6 glioma at different time points (60 min, 90 min, and 120 min) after injection and compared with 2-deoxy-2-[18F] fluoro-D-glucose ([18F]-FDG). Results [18F]-FP-Chlorotoxin was successfully synthesized in the radiochemical yield of 41% and the radiochemical purity of more than 98%. Among all the organs, the brain had the lowest and stable uptake of [18F]-FP-chlorotoxin, while the kidney showed the highest uptake. Compared with [18F]-FDG, a low uptake of [18F]-FP-chlorotoxin was detected in normal brain parenchyma and a high accumulation of [18F]-FP-chlorotoxin was found in the gliomas tissue. The glioma to normal brain uptake ratio of [18F]-FP-chlorotoxin was higher than that of [18F]-FDG. Furthermore, the uptake of [18F]-FP-chlorotoxin at 90 min after injection was better than that at 60 min after injection. Conclusions Compared with [18F]-FDG, [18F]-FP-chlorotoxin has a low and stable uptake in normal brain parenchyma. [18F]-FP-Chlorotoxin seems to be a potential PET tracer with a good performance in diagnosis of the glioma.
Collapse
|
24
|
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
|
25
|
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
|
26
|
Garbade SF, Shen N, Himmelreich N, Haas D, Trefz FK, Hoffmann GF, Burgard P, Blau N. Allelic phenotype values: a model for genotype-based phenotype prediction in phenylketonuria. Genet Med 2018; 21:580-590. [DOI: 10.1038/s41436-018-0081-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 05/31/2018] [Indexed: 02/08/2023] Open
|
27
|
Scherer T, Allegri G, Sarkissian CN, Ying M, Grisch-Chan HM, Rassi A, Winn SR, Harding CO, Martinez A, Thöny B. Tetrahydrobiopterin treatment reduces brain L-Phe but only partially improves serotonin in hyperphenylalaninemic ENU1/2 mice. J Inherit Metab Dis 2018; 41:709-718. [PMID: 29520738 PMCID: PMC6041158 DOI: 10.1007/s10545-018-0150-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 01/26/2018] [Accepted: 01/30/2018] [Indexed: 12/16/2022]
Abstract
Hyperphenylalaninemia (HPA) caused by hepatic phenylalanine hydroxylase (PAH) deficiency has severe consequences on brain monoamine neurotransmitter metabolism. We have studied monoamine neurotransmitter status and the effect of tetrahydrobiopterin (BH4) treatment in Pahenu1/enu2 (ENU1/2) mice, a model of partial PAH deficiency. These mice exhibit elevated blood L-phenylalanine (L-Phe) concentrations similar to that of mild hyperphenylalaninemia (HPA), but brain levels of L-Phe are still ~5-fold elevated compared to wild-type. We found that brain L-tyrosine, L-tryptophan, BH4 cofactor and catecholamine concentrations, and brain tyrosine hydroxylase (TH) activity were normal in these mice but that brain serotonin, 5-hydroxyindolacetic acid (5HIAA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) content, and brain TH protein, as well as tryptophan hydroxylase type 2 (TPH2) protein levels and activity were reduced in comparison to wild-type mice. Parenteral L-Phe loading conditions did not lead to significant changes in brain neurometabolite concentrations. Remarkably, enteral BH4 treatment, which normalized brain L-Phe levels in ENU1/2 mice, lead to only partial recovery of brain serotonin and 5HIAA concentrations. Furthermore, indirect evidence indicated that the GTP cyclohydrolase I (GTPCH) feedback regulatory protein (GFRP) complex may be a sensor for brain L-Phe elevation to ameliorate the toxic effects of HPA. We conclude that BH4 treatment of HPA toward systemic L-Phe lowering reverses elevated brain L-Phe content but the recovery of TPH2 protein and activity as well as serotonin levels is suboptimal, indicating that patients with mild HPA and mood problems (depression or anxiety) treated with the current diet may benefit from supplementation with BH4 and 5-OH-tryptophan.
Collapse
Affiliation(s)
- Tanja Scherer
- Department of Pediatrics, Divisions of Metabolism and of Clinical Chemistry and Biochemistry, University of Zürich, Zürich, Switzerland
| | - Gabriella Allegri
- Department of Pediatrics, Divisions of Metabolism and of Clinical Chemistry and Biochemistry, University of Zürich, Zürich, Switzerland
| | | | - Ming Ying
- Department of Biomedicine and K.G. Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, Bergen, Norway
| | - Hiu Man Grisch-Chan
- Department of Pediatrics, Divisions of Metabolism and of Clinical Chemistry and Biochemistry, University of Zürich, Zürich, Switzerland
| | - Anahita Rassi
- Department of Pediatrics, Divisions of Metabolism and of Clinical Chemistry and Biochemistry, University of Zürich, Zürich, Switzerland
| | - Shelley R Winn
- Department of Molecular and Medical Genetics, School of Medicine, Oregon Science & Health University, Portland, OR, USA
| | - Cary O Harding
- Department of Molecular and Medical Genetics, School of Medicine, Oregon Science & Health University, Portland, OR, USA
| | - Aurora Martinez
- Department of Biomedicine and K.G. Jebsen Centre for Neuropsychiatric Disorders, University of Bergen, Bergen, Norway.
| | - Beat Thöny
- Department of Pediatrics, Divisions of Metabolism and of Clinical Chemistry and Biochemistry, University of Zürich, Zürich, Switzerland.
| |
Collapse
|
28
|
Stráner P, Balogh E, Schay G, Arrondel C, Mikó Á, L'Auné G, Benmerah A, Perczel A, K Menyhárd D, Antignac C, Mollet G, Tory K. C-terminal oligomerization of podocin mediates interallelic interactions. Biochim Biophys Acta Mol Basis Dis 2018; 1864:2448-2457. [PMID: 29660491 DOI: 10.1016/j.bbadis.2018.04.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 03/22/2018] [Accepted: 04/11/2018] [Indexed: 01/01/2023]
Abstract
Interallelic interactions of membrane proteins are not taken into account while evaluating the pathogenicity of sequence variants in autosomal recessive disorders. Podocin, a membrane-anchored component of the slit diaphragm, is encoded by NPHS2, the major gene mutated in hereditary podocytopathies. We formerly showed that its R229Q variant is only pathogenic when trans-associated to specific 3' mutations and suggested the causal role of an abnormal C-terminal dimerization. Here we show by FRET analysis and size exclusion chromatography that podocin oligomerization occurs exclusively through the C-terminal tail (residues 283-382): principally through the first C-terminal helical region (H1, 283-313), which forms a coiled coil as shown by circular dichroism spectroscopy, and through the 332-348 region. We show the principal role of the oligomerization sites in mediating interallelic interactions: while the monomer-forming R286Tfs*17 podocin remains membranous irrespective of the coexpressed podocin variant identity, podocin variants with an intact H1 significantly influence each other's localization (r2 = 0.68, P = 9.2 × 10-32). The dominant negative effect resulting in intracellular retention of the pathogenic F344Lfs*4-R229Q heterooligomer occurs in parallel with a reduction in the FRET efficiency, suggesting the causal role of a conformational rearrangement. On the other hand, oligomerization can also promote the membrane localization: it can prevent the endocytosis of F344Lfs*4 or F344* podocin mutants induced by C-terminal truncation. In conclusion, C-terminal oligomerization of podocin can mediate both a dominant negative effect and interallelic complementation. Interallelic interactions of NPHS2 are not restricted to the R229Q variant and have to be considered in compound heterozygous individuals.
Collapse
Affiliation(s)
- Pál Stráner
- MTA-ELTE Protein Modeling Research Group and Laboratory of Structural Chemistry and Biology, Eötvös Loránd University, Budapest, Hungary
| | - Eszter Balogh
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary; Semmelweis University, Ist Department of Pediatrics, Budapest, Hungary
| | - Gusztáv Schay
- Semmelweis University, Department of Biophysics and Radiation Biology, Budapest, Hungary
| | - Christelle Arrondel
- Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Paris, France; Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Ágnes Mikó
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary; Semmelweis University, Ist Department of Pediatrics, Budapest, Hungary
| | - Gerda L'Auné
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary; Semmelweis University, Ist Department of Pediatrics, Budapest, Hungary
| | - Alexandre Benmerah
- Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Paris, France; Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - András Perczel
- MTA-ELTE Protein Modeling Research Group and Laboratory of Structural Chemistry and Biology, Eötvös Loránd University, Budapest, Hungary
| | - Dóra K Menyhárd
- MTA-ELTE Protein Modeling Research Group and Laboratory of Structural Chemistry and Biology, Eötvös Loránd University, Budapest, Hungary
| | - Corinne Antignac
- Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Paris, France; Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France; Assistance Publique - Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Département de Génétique, Paris, France
| | - Géraldine Mollet
- Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Paris, France; Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France
| | - Kálmán Tory
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary; Semmelweis University, Ist Department of Pediatrics, Budapest, Hungary; Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Paris, France; Université Paris Descartes-Sorbonne Paris Cité, Imagine Institute, Paris, France.
| |
Collapse
|
29
|
Wang R, Shen N, Ye J, Han L, Qiu W, Zhang H, Liang L, Sun Y, Fan Y, Wang L, Wang Y, Gong Z, Liu H, Wang J, Yan H, Blau N, Gu X, Yu Y. Mutation spectrum of hyperphenylalaninemia candidate genes and the genotype-phenotype correlation in the Chinese population. Clin Chim Acta 2018; 481:132-138. [PMID: 29499199 DOI: 10.1016/j.cca.2018.02.035] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 02/10/2018] [Accepted: 02/27/2018] [Indexed: 11/25/2022]
Abstract
BACKGROUND Hyperphenylalaninemia (HPA) is an inherited metabolic disorder that is caused by a deficiency of phenylalanine hydroxylase (PAH) or tetrahydrobiopterin. The prevalence of HPA varies widely around the world. METHODS A spectrum of HPA candidate genes in 1020 Chinese HPA patients was reported. Sanger sequencing, next generation sequencing (NGS), multiplex ligation-dependent probe amplification (MLPA) and quantitative real-time PCR (qRT-PCR) were applied to precisely molecular diagnose HPA patients. The allelic phenotype values (APV) and genotypic phenotype values (GPV) were calculated in PAH-deficient patients based on a recently developed formula. RESULTS Apart from genetic diagnoses confirmed in 915 HPA patients (89.7%) by Sanger sequencing, pathogenic variants were discovered in another 57 patients (5.6%) through deep detections (NGS, MLPA and qRT-PCR). We identified 196, 42, 10 and 2 variants in PAH, PTS, QDPR and GCH1, respectively. And a total of 47 novel variants were found in these genes. Through the APV and GPV calculations, it was found that the new GPV system was well correlated with metabolic phenotypes in most PAH-deficient patients. CONCLUSIONS More HPA candidate variants were identified using new molecular diagnostic methods. The new APV and GPV system is likely to be highly beneficial for predicting clinical phenotypes for PAH-deficient patients.
Collapse
Affiliation(s)
- Ruifang Wang
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Nan Shen
- Department of Rehabilitation Medicine, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Jun Ye
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Lianshu Han
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Wenjuan Qiu
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Huiwen Zhang
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Lili Liang
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Yu Sun
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Yanjie Fan
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Lili Wang
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Yu Wang
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Zhuwen Gong
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Huili Liu
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Jianguo Wang
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Hui Yan
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China
| | - Nenad Blau
- Dietmar-Hopp Metabolic Center, University Children's Hospital, 69120 Heidelberg, Germany.
| | - Xuefan Gu
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China.
| | - Yongguo Yu
- Department of Pediatric Endocrinology and Genetic Metabolism, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200092, China.
| |
Collapse
|
30
|
Jaffe EK. New protein structures provide an updated understanding of phenylketonuria. Mol Genet Metab 2017; 121:289-296. [PMID: 28645531 PMCID: PMC5549558 DOI: 10.1016/j.ymgme.2017.06.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 06/08/2017] [Indexed: 11/16/2022]
Abstract
Phenylketonuria (PKU) and less severe hyperphenylalaninemia (HPA) constitute the most common inborn error of amino acid metabolism, and is most often caused by defects in phenylalanine hydroxylase (PAH) function resulting in accumulation of Phe to neurotoxic levels. Despite the success of dietary intervention in preventing permanent neurological damage, individuals living with PKU clamor for additional non-dietary therapies. The bulk of disease-associated mutations are PAH missense variants, which occur throughout the entire 452 amino acid human PAH protein. While some disease-associated mutations affect protein structure (e.g. truncations) and others encode catalytically dead variants, most have been viewed as defective in protein folding/stability. Here we refine this view to address how PKU-associated missense variants can perturb the equilibrium among alternate native PAH structures (resting-state PAH and activated PAH), thus shifting the tipping point of this equilibrium to a neurotoxic Phe concentration. This refined view of PKU introduces opportunities for the design or discovery of therapeutic pharmacological chaperones that can help restore the tipping point to healthy Phe levels and how such a therapeutic might work with or without the inhibitory pharmacological chaperone BH4. Dysregulation of an equilibrium of architecturally distinct native PAH structures departs from the concept of "misfolding", provides an updated understanding of PKU, and presents an enhanced foundation for understanding genotype/phenotype relationships.
Collapse
Affiliation(s)
- Eileen K Jaffe
- Fox Chase Cancer Center - Temple University Health System, 333 Cottman Ave, Philadelphia, PA 19111, USA.
| |
Collapse
|
31
|
CRISPR RNA-guided FokI nucleases repair a PAH variant in a phenylketonuria model. Sci Rep 2016; 6:35794. [PMID: 27786189 PMCID: PMC5081532 DOI: 10.1038/srep35794] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/05/2016] [Indexed: 01/17/2023] Open
Abstract
The CRISPR/Cas9 system is a recently developed genome editing technique. In this study, we used a modified CRISPR system, which employs the fusion of inactive Cas9 (dCas9) and the FokI endonuclease (FokI-dCas9) to correct the most common variant (allele frequency 21.4%) in the phenylalanine hydroxylase (PAH) gene - c.1222C>T (p.Arg408Trp) - as an approach toward curing phenylketonuria (PKU). PKU is the most common inherited diseases in amino acid metabolism. It leads to severe neurological and neuropsychological symptoms if untreated or late diagnosed. Correction of the disease-causing variants could rescue residual PAH activity and restore normal function. Co-expression of a single guide RNA plasmid, a FokI-dCas9-zsGreen1 plasmid, and the presence of a single-stranded oligodeoxynucleotide in PAH_c.1222C>T COS-7 cells – an in vitro model for PKU – corrected the PAH variant and restored PAH activity. Also in this system, the HDR enhancer RS-1 improved correction efficiency. This proof-of-concept indicates the potential of the FokI-dCas9 system for precision medicine, in particular for targeting PKU and other monogenic metabolic diseases.
Collapse
|
32
|
Abstract
More than 950 phenylalanine hydroxylase (PAH) gene variants have been identified in people with phenylketonuria (PKU). These vary in their consequences for the residual level of PAH activity, from having little or no effect to abolishing PAH activity completely. Advances in genotyping technology and the availability of locus-specific and genotype databases have greatly expanded our understanding of the correlations between individual gene variant, residual PAH activity, tetrahydrobiopterin (BH4 ) responsiveness, and the clinical PKU phenotype. Most patients (∼76%) have compound heterozygous PAH gene variants and one mutated allele may markedly influence the activity of the second mutated allele, which in turn may influence either positively or negatively the activity of the biologically active heterotetrameric form of the PAH. While it is possible to predict the level of BH4 responsiveness (∼71%) and PKU severity (∼78%) from the nature of the underlying gene variants, these relationships remain complex and incompletely understood. A greater understanding of these relationships may increase the potential for individualized management of PKU in future. Inherited deficiencies in BH4 metabolism account for about 1%-2% of all hyperphenylalaninemias and are clinically more severe than PKU. Almost 90% of all patients are deficient in 6-pyruvoyl-tetrahydropterin synthase and dihydropteridine reductase.
Collapse
Affiliation(s)
- Nenad Blau
- Dietmar-Hopp-Metabolic Center, University Children's Hospital, Heidelberg, Germany
| |
Collapse
|