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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] [MESH Headings] [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.
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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.
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Zhang X, Ji W, Wang Y, Zhou Z, Guo J, Tian G. Comparative analysis of inherited metabolic diseases in normal newborns and high-risk children: Insights from a 10-year study in Shanghai. Clin Chim Acta 2024; 558:117893. [PMID: 38582244 DOI: 10.1016/j.cca.2024.117893] [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: 08/15/2023] [Revised: 03/11/2024] [Accepted: 03/27/2024] [Indexed: 04/08/2024]
Abstract
BACKGROUND Compare the differences between normal newborns and high-risk children with inherited metabolic diseases. The disease profile includes amino acidemias, fatty acid oxidation disorders, and organic acidemias. METHODS Data was collected on newborns and children from high-risk populations in Shanghai from December 2010 to December 2020. RESULTS 232,561 newborns were screened for disorders of organic, amino acid, and fatty acid metabolism. The initial positive rate was 0.66 % (1,526/232,561) and the positive recall rate was 77.85 %. The positive predictive value is 4.71 %. Among them, 56 cases were diagnosed as metabolic abnormalities. The total incidence rate is 1:4153. Hyperphenylalaninemia and short-chain acyl-CoA dehydrogenase are the most common diseases in newborns. In addition, in 56 children, 39 (69.42 %) were diagnosed by genetic sequencing. Some hotspot mutations in 14 IEMs have been observed, including PAH gene c.728G > A, c.611A > G, and ACADS gene c. 1031A > G, c.164C > T. A total of 49,860 symptomatic patients were screened, of which 185 were diagnosed with IEM, with a detection rate of 0.37 %. The most commonly diagnosed diseases in high-risk infants aremethylmalonic acidemia and hyperphenylalaninemia. CONCLUSION There are more clinical cases of congenital metabolic errors diagnosed by tandem mass spectrometry than newborn screening. The spectrum of diseases, prevalence, and genetic characteristics of normal newborns and high-risk children are quite different.
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Affiliation(s)
- Xiaofen Zhang
- Department of Newborn Screening Center, Shanghai Children's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200040, China.
| | - Wei Ji
- Department of Newborn Screening Center, Shanghai Children's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200040, China.
| | - Yanmin Wang
- Department of Newborn Screening Center, Shanghai Children's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200040, China.
| | - Zhuo Zhou
- Department of Newborn Screening Center, Shanghai Children's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200040, China.
| | - Jing Guo
- Department of Newborn Screening Center, Shanghai Children's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200040, China.
| | - Guoli Tian
- Department of Newborn Screening Center, Shanghai Children's Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200040, China.
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Tebieva IS, Mishakova PV, Gabisova YV, Khokhova AV, Kaloeva TG, Marakhonov AV, Shchagina OA, Polyakov AV, Ginter EK, Kutsev SI, Zinchenko RA. Genetic Landscape and Clinical Features of Hyperphenylalaninemia in North Ossetia-Alania: High Frequency of P281L and P211T Genetic Variants in the PAH Gene. Int J Mol Sci 2024; 25:4598. [PMID: 38731816 PMCID: PMC11083185 DOI: 10.3390/ijms25094598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2024] [Revised: 03/30/2024] [Accepted: 04/05/2024] [Indexed: 05/13/2024] Open
Abstract
This study, conducted in the Republic of North Ossetia-Alania (RNOA), aimed to explore the genetic landscape of hyperphenylalaninemia (HPA) and phenylketonuria (PKU) in the Ossetian population using data from newborn screening (NBS). Through comprehensive molecular genetic analysis of 29 patients with HPA from diverse ethnic backgrounds, two major genetic variants in the PAH gene, P281L and P211T, were identified, constituting 50% of all detected pathogenic alleles in Ossetian patients. Remarkably, these variants exhibited an exceptionally high frequency in the Ossetian population, surpassing global prevalence rates. This study unveiled a notable prevalence of mild forms of HPA (78%), underscoring the importance of genetic counseling for carriers of pathogenic variants in the PAH gene. Moreover, the findings emphasized the necessity for ongoing monitoring of patients with mild forms, as they may lack significant symptoms for diagnosis, potentially impacting offspring. Overall, this research offers valuable insights into the genetic landscape of HPA and PKU in the Ossetian population.
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Affiliation(s)
- Inna S. Tebieva
- North-Ossetian State Medical Academy, 362003 Vladikavkaz, Russia; (I.S.T.); (T.G.K.)
- Republican Children’s Clinical Hospital, 362003 Vladikavkaz, Russia; (Y.V.G.); (A.V.K.)
| | - Polina V. Mishakova
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (P.V.M.); (A.V.M.); (O.A.S.); (A.V.P.); (E.K.G.); (S.I.K.)
| | - Yulia V. Gabisova
- Republican Children’s Clinical Hospital, 362003 Vladikavkaz, Russia; (Y.V.G.); (A.V.K.)
| | - Alana V. Khokhova
- Republican Children’s Clinical Hospital, 362003 Vladikavkaz, Russia; (Y.V.G.); (A.V.K.)
| | - Tamara G. Kaloeva
- North-Ossetian State Medical Academy, 362003 Vladikavkaz, Russia; (I.S.T.); (T.G.K.)
| | - Andrey V. Marakhonov
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (P.V.M.); (A.V.M.); (O.A.S.); (A.V.P.); (E.K.G.); (S.I.K.)
| | - Olga A. Shchagina
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (P.V.M.); (A.V.M.); (O.A.S.); (A.V.P.); (E.K.G.); (S.I.K.)
| | - Alexander V. Polyakov
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (P.V.M.); (A.V.M.); (O.A.S.); (A.V.P.); (E.K.G.); (S.I.K.)
| | - Evgeny K. Ginter
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (P.V.M.); (A.V.M.); (O.A.S.); (A.V.P.); (E.K.G.); (S.I.K.)
| | - Sergey I. Kutsev
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (P.V.M.); (A.V.M.); (O.A.S.); (A.V.P.); (E.K.G.); (S.I.K.)
| | - Rena A. Zinchenko
- Research Centre for Medical Genetics, 115522 Moscow, Russia; (P.V.M.); (A.V.M.); (O.A.S.); (A.V.P.); (E.K.G.); (S.I.K.)
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Upadia J, Crivelly K, Noh G, Cunningham A, Cerminaro C, Li Y, Mckoin M, Chenevert M, Andersson HC. Maximal dietary responsiveness after tetrahydrobiopterin (BH4) in 19 phenylalanine hydroxylase deficiency patients: What super-responders can expect. Mol Genet Metab Rep 2024; 38:101050. [PMID: 38469087 PMCID: PMC10926188 DOI: 10.1016/j.ymgmr.2024.101050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 01/05/2024] [Indexed: 03/13/2024] Open
Abstract
Background Inherited phenylalanine hydroxylase deficiency, also known as phenylketonuria (PKU), causes poor growth and neurologic deficits in the untreated state. After ascertainment through newborn screen and dietary phenylalanine (Phe) restriction to achieve plasma Phe in the range of 120-360 μmol/L, these disease manifestations can be prevented. Poor compliance with protein restricted diets supported by medical food is typical in later years, beginning in the late toddler and teenage years. Pharmacologic doses of oral tetrahydrobiopterin (BH4; sapropterin dihydrochloride) is effective in reducing plasma Phe in about 40-50% of PKU patients but effectiveness is highly variable. Objective To assess the maximal responsiveness to 20 mg/kg/day oral BH4 as it affects plasma Phe and dietary Phe allowance in PKU patients. Materials and methods This was a single-center, retrospective observational study, combining case reports of individual patients. We reported an outcome of 85 patients with PKU who were trialed on BH4. Phe levels and dietary records of 19 BH4 "super-responders" were analyzed. Results Overall, 63.5% of the patients (54/85) were considered BH4 responders. However, we quantitated the dietary liberalization of 19 of our responsive patients (35%), those with at least a 2-fold increase in dietary Phe and maintenance of plasma Phe in treatment range. In these "super-responders", the mean plasma Phe at baseline was 371 ± 237 μmol/L and decreased to 284 ± 273 μmol/L after 1 year on BH4. Mean dietary Phe tolerance increased significantly from 595 ± 256 to 2260 ± 1414 mg/day (p ≤0.0001), while maintaining mean plasma Phe levels within treatment range. Four patients no longer required dietary Phe restriction and could discontinue medical food. The majority of patients had at least one BH4-responsive genotype. Conclusion This cohort demonstrates the maximally achievable dietary liberalization which some PKU patients may expect with BH4 therapy. Health benefits are considered to accrue in patients with increased intact protein.
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Affiliation(s)
- Jariya Upadia
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Kea Crivelly
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Grace Noh
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Amy Cunningham
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Caroline Cerminaro
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Yuwen Li
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Meredith Mckoin
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Madeline Chenevert
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
| | - Hans C. Andersson
- Hayward Genetics Center, New Orleans, LA 70112, USA
- Department of Pediatrics, Tulane University School of Medicine, New Orleans, LA 70112, USA
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5
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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.
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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)
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Tokatly Latzer I, Roullet JB, Cesaro S, DiBacco ML, Arning E, Rotenberg A, Lee HHC, Opladen T, Jeltsch K, García-Cazorla À, Juliá-Palacios N, Gibson KM, Bertoldi M, Pearl PL. Phenotypic correlates of structural and functional protein impairments resultant from ALDH5A1 variants. Hum Genet 2023; 142:1755-1776. [PMID: 37962671 DOI: 10.1007/s00439-023-02613-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Accepted: 10/27/2023] [Indexed: 11/15/2023]
Abstract
To investigate the genotype-to-protein-to-phenotype correlations of succinic semialdehyde dehydrogenase deficiency (SSADHD), an inherited metabolic disorder of γ-aminobutyric acid catabolism. Bioinformatics and in silico mutagenesis analyses of ALDH5A1 variants were performed to evaluate their impact on protein stability, active site and co-factor binding domains, splicing, and homotetramer formation. Protein abnormalities were then correlated with a validated disease-specific clinical severity score and neurological, neuropsychological, biochemical, neuroimaging, and neurophysiological metrics. A total of 58 individuals (1:1 male/female ratio) were affected by 32 ALDH5A1 pathogenic variants, eight of which were novel. Compared to individuals with single homotetrameric or multiple homo and heterotetrameric proteins, those predicted not to synthesize any functional enzyme protein had significantly lower expression of ALDH5A1 (p = 0.001), worse overall clinical outcomes (p = 0.008) and specifically more severe cognitive deficits (p = 0.01), epilepsy (p = 0.04) and psychiatric morbidity (p = 0.04). Compared to individuals with predictions of having no protein or a protein impaired in catalytic functions, subjects whose proteins were predicted to be impaired in stability, folding, or oligomerization had a better overall clinical outcome (p = 0.02) and adaptive skills (p = 0.04). The quantity and type of enzyme proteins (no protein, single homotetramers, or multiple homo and heterotetramers), as well as their structural and functional impairments (catalytic or stability, folding, or oligomerization), contribute to phenotype severity in SSADHD. These findings are valuable for assessment of disease prognosis and management, including patient selection for gene replacement therapy. Furthermore, they provide a roadmap to determine genotype-to-protein-to-phenotype relationships in other autosomal recessive disorders.
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Affiliation(s)
- Itay Tokatly Latzer
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Ave, Boston, MA, 02115, USA
- Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - Jean-Baptiste Roullet
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Samuele Cesaro
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Strada Le Grazie 8, 37134, Verona, VR, Italy
| | - Melissa L DiBacco
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Ave, Boston, MA, 02115, USA
| | - Erland Arning
- Institute of Metabolic Disease, Baylor Scott & White Research Institute, Dallas, TX, USA
| | - Alexander Rotenberg
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Ave, Boston, MA, 02115, USA
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Henry H C Lee
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA
- Rosamund Stone Zander Translational Neuroscience Center, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Thomas Opladen
- Division of Neuropediatrics and Metabolic Medicine, University Children's Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany
| | - Kathrin Jeltsch
- Division of Neuropediatrics and Metabolic Medicine, University Children's Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany
| | - Àngels García-Cazorla
- Neurometabolic Unit, Neurology Department, Institut de Recerca, Hospital Sant Joan de Déu, Barcelona, Spain
| | - Natalia Juliá-Palacios
- Neurometabolic Unit, Neurology Department, Institut de Recerca, Hospital Sant Joan de Déu, Barcelona, Spain
| | - K Michael Gibson
- Department of Pharmacotherapy, College of Pharmacy and Pharmaceutical Sciences, Washington State University, Spokane, WA, USA
| | - Mariarita Bertoldi
- Department of Neuroscience, Biomedicine and Movement Sciences, University of Verona, Strada Le Grazie 8, 37134, Verona, VR, Italy.
| | - Phillip L Pearl
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Ave, Boston, MA, 02115, USA.
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7
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Vela-Amieva M, Alcántara-Ortigoza MA, González-del Angel A, Ibarra-González I, Fernández-Hernández L, Guillén-López S, López-Mejía L, Fernández-Lainez C. In Silico Structural Protein Evaluation of the Phenylalanine Hydroxylase p.(Tyr77His) Variant Associated with Benign Hyperphenylalaninemia as Identified through Mexican Newborn Screening. CHILDREN (BASEL, SWITZERLAND) 2023; 10:1865. [PMID: 38136067 PMCID: PMC10742057 DOI: 10.3390/children10121865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 11/23/2023] [Accepted: 11/24/2023] [Indexed: 12/24/2023]
Abstract
Hyperphenylalaninemia (HPA), which includes phenylketonuria (PKU), is a genetic autosomal recessive disorder arising from a deficiency in the enzyme named phenylalanine hydroxylase (PAH). Affected patients can experience severe and irreversible neurological impairments when phenylalanine (Phe) blood concentration exceeds 360 μmol/L (6 mg/dL). Here, we describe a female HPA patient who was born in Mexico to Cuban non-consanguineous parents and identified by newborn screening, and who bears the previously unreported PAH NM_000277.3(PAH):c.[229T>C];[1222C>T] or p.[Tyr77His];[Arg408Trp] genotype. At diagnosis, the patient showed a Phe blood level of 321 μmol/L (5.3 mg/dL), indicative of mild HPA. Neither of the PAH variants found in this patient had been previously reported in the mutational PAH spectrum of the Mexican population. The c.229T>C or p.(Tyr77His) PAH variant was previously related to mild HPA in the Swedish population. Our in silico structural analysis and molecular docking showed that mutated His 77 residue is located in the allosteric site of PAH at the interface of the two monomers. The PDBsum in silico tool predicted that this variant would cause minimal structural disturbance of the protein interface in the presence of Phe at the allosteric site. Docking studies revealed that these structural changes might be attenuated by the allosteric effect of Phe. Given the classic PKU phenotype conditioned by the "Celtic" or c.[1222C>T] or p.(Arg408Trp) PAH variant, which is the second variant in this patient, we propose that p.(Tyr77His) has a hypomorphic feature that could explain her mild HPA phenotype. Our results show the importance of following up on cases detected by NBS and the value of genetic studies and in silico tools that aid in the establishment of correct therapeutic strategies.
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Affiliation(s)
- Marcela Vela-Amieva
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico; (M.V.-A.); (S.G.-L.); (L.L.-M.)
| | - Miguel Angel Alcántara-Ortigoza
- Laboratorio de Biología Molecular, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico; (M.A.A.-O.); (A.G.-d.A.); (L.F.-H.)
- Centro de Alta Especialidad en Genética Humana DNA-GEN S.C., Ciudad de México 14070, Mexico
| | - Ariadna González-del Angel
- Laboratorio de Biología Molecular, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico; (M.A.A.-O.); (A.G.-d.A.); (L.F.-H.)
- Centro de Alta Especialidad en Genética Humana DNA-GEN S.C., Ciudad de México 14070, Mexico
| | - Isabel Ibarra-González
- Unidad de Genética de la Nutrición, Instituto de Investigaciones Biomédicas UNAM, Ciudad de México 04510, Mexico;
| | - Liliana Fernández-Hernández
- Laboratorio de Biología Molecular, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico; (M.A.A.-O.); (A.G.-d.A.); (L.F.-H.)
| | - Sara Guillén-López
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico; (M.V.-A.); (S.G.-L.); (L.L.-M.)
| | - Lizbeth López-Mejía
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico; (M.V.-A.); (S.G.-L.); (L.L.-M.)
| | - Cynthia Fernández-Lainez
- Laboratorio de Errores Innatos del Metabolismo y Tamiz, Instituto Nacional de Pediatría, Secretaría de Salud, Ciudad de México 04530, Mexico; (M.V.-A.); (S.G.-L.); (L.L.-M.)
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Ziegler SG, Kim J, Ehmsen JT, Vernon HJ. Inborn errors of amino acid metabolism - from underlying pathophysiology to therapeutic advances. Dis Model Mech 2023; 16:dmm050233. [PMID: 37994477 PMCID: PMC10690057 DOI: 10.1242/dmm.050233] [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: 04/06/2023] [Accepted: 10/19/2023] [Indexed: 11/24/2023] Open
Abstract
Amino acids are organic molecules that serve as basic substrates for protein synthesis and have additional key roles in a diverse array of cellular functions, including cell signaling, gene expression, energy production and molecular biosynthesis. Genetic defects in the synthesis, catabolism or transport of amino acids underlie a diverse class of diseases known as inborn errors of amino acid metabolism. Individually, these disorders are rare, but collectively, they represent an important group of potentially treatable disorders. In this Clinical Puzzle, we discuss the pathophysiology, clinical features and management of three disorders that showcase the diverse clinical presentations of disorders of amino acid metabolism: phenylketonuria, lysinuric protein intolerance and homocystinuria due to cystathionine β-synthase (CBS) deficiency. Understanding the biochemical perturbations caused by defects in amino acid metabolism will contribute to ongoing development of diagnostic and management strategies aimed at improving the morbidity and mortality associated with this diverse group of disorders.
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Affiliation(s)
- Shira G. Ziegler
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jiyoung Kim
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jeffrey T. Ehmsen
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Internal Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hilary J. Vernon
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Bonfim‐Freitas PE, Andrade RS, Ribeiro‐dos‐Santos ÂK, Silva LCS. Molecular characterization of phenylketonuria patients from the North Region of Brazil: State of Pará. Mol Genet Genomic Med 2023; 11:e2224. [PMID: 37421234 PMCID: PMC10568386 DOI: 10.1002/mgg3.2224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 05/23/2023] [Indexed: 07/10/2023] Open
Abstract
BACKGROUND Phenylketonuria (PKU) is an autosomal recessive disease resulting from a deficiency of the enzyme phenylalanine hydroxylase (PAH). Hyperphenylalaninemias (HPA) due to PAH deficiency are accompanied by a wide variety of clinical, biochemical, and molecular features. To identify and characterize pathogenic variants in the PAH gene and establish a correlation between genotype and biochemical phenotype in patients with PKU from state of Pará in the North Region of Brazil. METHODS All 13 exons of the PAH gene from 32 patients (21 PKU and 11 non-PKU HPA) were amplified by PCR and submitted to DNA sequencing (Sanger). Biochemical data were obtained from the patients' medical records. RESULTS Molecular analysis identified 17 pathogenic variants and 3 nonpathogenic variants. The most frequent pathogenic variants were IVS10-11G>A (7.9%), p. Arg261Gln (7.9%), p. Val388Met (6.3%) and p. Ile65Thr (4.7%). Was observed correlations and inconsistencies between genotype and biochemical phenotype. CONCLUSION In PKU patients from state of Pará, North Region of Brazil, a heterogeneous mutation spectrum was revealed, in which the most frequent mutations are variants commonly observed in other Brazilian studies and in the region of the Iberian Peninsula.
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Affiliation(s)
- Pedro E. Bonfim‐Freitas
- Laboratory of Inborn Errors of MetabolismInstitute of Biological Sciences, Federal University of ParáBelémBrazil
- Present address:
Hepatology DepartmentEvandro Chagas InstituteBelémPABrazil
| | - Roseani S. Andrade
- Faculty of NutritionInstitute of Health Sciences, Federal University of ParáBelémBrazil
| | | | - Luiz C. Santana‐da Silva
- Laboratory of Inborn Errors of MetabolismInstitute of Biological Sciences, Federal University of ParáBelémBrazil
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10
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Latzer IT, Roullet JB, Cesaro S, DiBacco ML, Arning E, Rotenberg A, Lee HHC, Opladen T, Jeltsch K, García-Cazorla À, Juliá-Palacios N, Gibson KM, Bertoldi M, Pearl PL. Phenotypic Correlates of Structural and Functional Protein Impairments Resultant from ALDH5A1 Variants. RESEARCH SQUARE 2023:rs.3.rs-3111263. [PMID: 37503297 PMCID: PMC10371128 DOI: 10.21203/rs.3.rs-3111263/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Objective To investigate the genotype-to-protein-to-phenotype correlations of succinic semialdehyde dehydrogenase deficiency (SSADHD), an inherited metabolic disorder of γ-aminobutyric acid catabolism. Methods Bioinformatics and in silico mutagenesis analyses of ALDH5A1 variants were performed to evaluate their impact on protein stability, active site and co-factor binding domains, splicing, and homotetramer formation. Protein abnormalities were then correlated with a validated disease-specific clinical severity score and neurological, neuropsychological, biochemical, neuroimaging, and neurophysiological metrics. Results A total of 58 individuals (1:1 male/female ratio) were affected by 32 ALDH5A1 pathogenic variants, eight of which were novel. Compared to individuals with single homotetrameric or multiple homo and heterotetrameric proteins, those predicted not to synthesize any functional enzyme protein had significantly lower expression of ALDH5A1 (p = 0.001), worse overall clinical outcomes (p = 0.008) and specifically more severe cognitive deficits (p = 0.01), epilepsy (p = 0.04) and psychiatric morbidity (p = 0.04). Compared to individuals with predictions of having no protein or a protein impaired in catalytic functions, subjects whose proteins were predicted to be impaired in stability, folding, or oligomerization had a better overall clinical outcome (p = 0.02) and adaptive skills (p = 0.04). Conclusions The quantity and type of enzyme proteins (no protein, single homotetramers, or multiple homo and heterotetramers), as well as their structural and functional impairments (catalytic or stability, folding, or oligomerization), contribute to phenotype severity in SSADHD. These findings are valuable for assessment of disease prognosis and management, including patient selection for gene replacement therapy. Furthermore, they provide a roadmap to determine genotype-to-protein-to-phenotype relationships in other autosomal recessive disorders.
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11
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Zhang C, Zhang P, Yan Y, Zhou B, Wang Y, Tian X, Hao S, Ma P, Zheng L, Zhang Q, Hui L, Wang Y, Cao Z, Ma X. The spectrum of phenylalanine hydroxylase variants and genotype-phenotype correlation in phenylketonuria patients in Gansu, China. Hum Genomics 2023; 17:36. [PMID: 37098607 PMCID: PMC10127316 DOI: 10.1186/s40246-023-00475-7] [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: 12/01/2022] [Accepted: 03/15/2023] [Indexed: 04/27/2023] Open
Abstract
BACKGROUND Phenylketonuria (PKU) is a common, congenital, autosomal recessive, metabolic disorder caused by Phenylalanine hydroxylase (PAH) variants. METHODS 967 PKU patients from Gansu, China were genotyped by Sanger sequencing, multiplex ligation-dependent probe amplification, and whole exome sequencing. We analyzed the variants of PAH exons, their flanking sequences, and introns. RESULTS The detection of deep intronic variants in PAH gene can significantly improve the genetic diagnostic rate of PKU. The distribution of PAH variants among PKU subtypes may be related to the unique genetic background in Gansu, China. CONCLUSION The identification of PAH hotspot variants will aid the development of large-scale neonatal genetic screening for PKU. The five new PAH variants found in this study further expand the spectrum of PAH variants. Genotype-phenotype correlation analysis may help predict the prognosis of PKU patients and enable precise treatment regimens to be developed.
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Affiliation(s)
- Chuan Zhang
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
- National Research Institute for Family Planning , National Human Genetic Resources Center, Beijing, China
| | - Pei Zhang
- Department of Nosocomial Infection Management, Lanzhou University Second Hospital, Lanzhou, China
| | - Yousheng Yan
- Prenatal Diagnostic Center, Beijing Obstetrics and Gynecology Hospital, Capital Medical University, Beijing, China
| | - Bingbo Zhou
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Yupei Wang
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Xinyuan Tian
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Shengju Hao
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Panpan Ma
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Lei Zheng
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Qinghua Zhang
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Ling Hui
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Yan Wang
- Gansu Province Medical Genetics Center,Gansu Provincial Clinical Research Center for Birth Defects and Rare Diseases, Gansu Provincial Maternity and Child-Care Hospital, Lanzhou, China
| | - Zongfu Cao
- National Research Institute for Family Planning , National Human Genetic Resources Center, Beijing, China.
| | - Xu Ma
- National Research Institute for Family Planning , National Human Genetic Resources Center, Beijing, China.
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12
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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.
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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
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13
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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.
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14
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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.
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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
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15
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The pathogenicity classification of PAH gene variants in the Iranian population. Comput Biol Chem 2022; 98:107665. [PMID: 35339094 DOI: 10.1016/j.compbiolchem.2022.107665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Revised: 02/11/2022] [Accepted: 03/10/2022] [Indexed: 12/29/2022]
Abstract
Till now not many studies have been conducted to classify PAH gene variants according to American College of Medical Genetics and Genomics (ACMG-AMP) guidelines. The aim of this study was to collect all PAH gene variants reported among Iranian population and investigate their pathogenicity based on ACMG-AMP guidelines. Systematic collection of PAH gene variants, verification of variants, in silico analysis, and application of ACMG-AMP guidelines were the main steps in performing the present study. A total of 267 unique variants were identified; according to ACMG-AMP guidelines, 90, 40, 71, 14, and 52 variants were classified as pathogenic (P), likely pathogenic (LP), variant of uncertain significance (VUS), likely benign (LB), and benign (B), respectively. The need to pay more attention to synonymous and missense variants with low or no impact on protein function as well as intronic variants, whether they are deep or are close to intron/exon boundaries, was a highlight of this study. Due to the fact that few functional studies are performed on these variants, it is suggested that they be analyzed first using bioinformatics tools, and if positive results are obtained, then functional studies can be designed.
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Characterization of phenylalanine hydroxylase gene variants and analysis of genotype-phenotype correlation in patients with phenylalanine hydroxylase deficiency from Fujian Province, Southeastern China. Mol Biol Rep 2022; 49:10409-10419. [PMID: 36104584 PMCID: PMC9618490 DOI: 10.1007/s11033-022-07579-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 05/06/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND Phenylalanine hydroxylase deficiency (PAHD) is the most prevalent inherited disorder of amino acid metabolism in China. Its complex phenotype includes many variants and genotypes among different populations. METHODS AND RESULTS In this study, we analyzed the phenylalanine hydroxylase gene (PAH) variants in a cohort of 93 PAHD patients from Fujian Province. We also assessed genotype and phenotype correlation in patients with PAHD. A total of 44 different pathogenic variants were identified, including five novel variants. The three most prevalent variants among all patents were c.158G > A, p.(Arg53His) (18.03%), c.721C > T, p.(Arg241Cys) (14.75%), and c.728G > A, p.(Arg243Gln) (7.65%). The frequency of the c.158G > A, p.(Arg53His) variant was highest in patients with mild hyperphenylalaninemia, whereas the frequency of the c.1197A > T, p.(Val399 =) and c.331C > T, p.(Arg111Ter) variants was highest in patients with classic phenylketonuria. The most abundant genotypes observed in PAHD patients were c.[158G > A];[728G > A], c.[158G > A];[442-1G > A], and c.[158G > A];[721C > T]. Comparing allelic phenotype to genotypic phenotype values yielded fairly accurate predictions of phenotype, with an overall consistency rate was 85.71% for PAHD patients. CONCLUSIONS Our study identified a PAH variant spectrum in PAHD patients from Fujian Province, Southeastern China. Quantitative correlation analysis between genotype and phenotype severity is helpful for genetic counseling and management.
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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.
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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
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18
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Wang X, Wang Y, Ma D, Zhang Z, Li Y, Yang P, Sun Y, Jiang T. Neonatal screening and genotype-phenotype correlation of hyperphenylalaninemia in the Chinese population. Orphanet J Rare Dis 2021; 16:214. [PMID: 33980295 PMCID: PMC8114530 DOI: 10.1186/s13023-021-01846-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 05/04/2021] [Indexed: 11/10/2022] Open
Abstract
Background Hyperphenylalaninemia (HPA) is the most common amino acid metabolic disease involving phenylalanine hydroxylase (PAH, OMIM*612,349) deficiency or coenzyme tetrahydrobiopterin (BH4) deficiency. Patients with severe HPA often have a difficult life. Early diagnosis of HPA before the development of symptoms is possible via neonatal screening, facilitating appropriate treatment and reducing mortality and disability rates. This study revealed the prevalence, mutational and phenotypic spectrum, and prognosis of HPA by neonatal screening from January 2001 to September 2020 in Nanjing, Jiangsu Province, China. Methods Through a retrospective analysis of the information available in the neonatal screening database, the clinical presentations, laboratory data, molecular characteristics and treatment follow-up data of HPA patients detected by neonatal screening were evaluated. Results We diagnosed 181 patients with HPA from 1 to 957 newborns, giving an incidence of 1:6873. Among these patients, 177 were identified as PAH deficient and four patients were BH4 deficient. The average current age of the patients was 6.38 years old. The most common mutations of PAH were c.728 C > A/ p.Arg243Gln (13.83 %), c.158G > A/ p.Arg53His (9.57 %), c.611 A > G/ p.Tyr204Cys (7.44 %), and c.721 C > T/ p.Arg241Cys (6.38 %). Conclusions This study revealed the prevalence, phenotype-genotype, and prognosis of HPA in China and contributes to the updating of PAHD data for China and worldwide. Our study not only expanded the spectrum of phenotypes and genotype but also provided a valuable tool for improved genetic counseling and management of future cases. Supplementary Information The online version contains supplementary material available at 10.1186/s13023-021-01846-w.
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Affiliation(s)
- Xin Wang
- Genetic Medicine Center, Nanjing Maternity and Child Health Care Hospital, Women's Hospital of Nanjing Medical University, 123 Tianfei St., Qinhuai District, Nanjing, 210004, People's Republic of China
| | - Yanyun Wang
- Genetic Medicine Center, Nanjing Maternity and Child Health Care Hospital, Women's Hospital of Nanjing Medical University, 123 Tianfei St., Qinhuai District, Nanjing, 210004, People's Republic of China
| | - Dingyuan Ma
- Genetic Medicine Center, Nanjing Maternity and Child Health Care Hospital, Women's Hospital of Nanjing Medical University, 123 Tianfei St., Qinhuai District, Nanjing, 210004, People's Republic of China
| | - Zhilei Zhang
- Genetic Medicine Center, Nanjing Maternity and Child Health Care Hospital, Women's Hospital of Nanjing Medical University, 123 Tianfei St., Qinhuai District, Nanjing, 210004, People's Republic of China
| | - Yahong Li
- Genetic Medicine Center, Nanjing Maternity and Child Health Care Hospital, Women's Hospital of Nanjing Medical University, 123 Tianfei St., Qinhuai District, Nanjing, 210004, People's Republic of China
| | - Peiying Yang
- Genetic Medicine Center, Nanjing Maternity and Child Health Care Hospital, Women's Hospital of Nanjing Medical University, 123 Tianfei St., Qinhuai District, Nanjing, 210004, People's Republic of China
| | - Yun Sun
- Genetic Medicine Center, Nanjing Maternity and Child Health Care Hospital, Women's Hospital of Nanjing Medical University, 123 Tianfei St., Qinhuai District, Nanjing, 210004, People's Republic of China
| | - Tao Jiang
- Genetic Medicine Center, Nanjing Maternity and Child Health Care Hospital, Women's Hospital of Nanjing Medical University, 123 Tianfei St., Qinhuai District, Nanjing, 210004, People's Republic of China.
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19
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Tao Y, Han D, Shen H, Li X. Spectrum of PAH gene mutations and genotype-phenotype correlation in patients with phenylalanine hydroxylase deficiency from Shanxi province. Brain Dev 2021; 43:220-229. [PMID: 32893076 DOI: 10.1016/j.braindev.2020.08.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 08/04/2020] [Accepted: 08/18/2020] [Indexed: 01/12/2023]
Abstract
BACKGROUND Phenylalanine hydroxylase deficiency (PAHD) is an autosomal recessive inborn error that affects phenylalanine (Phe) metabolism. It has a complex phenotype with many variants and genotypes among different populations. Shanxi province is a high-prevalence area of PAHD in China. METHODS In this study, eighty-nine PAHD patients were subjected to genetic testing using Sanger sequencing, followed by multiplex ligation-dependent probe amplification analysis (MLPA). Allelic and genotypic phenotype values (APV and GPV, respectively) were used for genotype-based phenotypic prediction. RESULTS Fifty-one types of variants, including three novel forms, were identified. The predominant variant was p.R243Q (22.09%), followed by p.R53H (10.47%), p.EX6-96A > G (9.30%), p.V399V (5.23%) and p.R413P (3.49%). Notably, mild hyperphenylalaninemia (MHP) has a high prevalence in this region (up to 45.76%), and the variant p.R53H was solely observed in patients of MHP. According to the genotype-phenotype prediction, the APV/GPV system was well correlated with the metabolic phenotype of most PAHD patients. CONCLUSION We have systematically constructed the mutational and phenotypic spectrum of PAH in Shanxi province. Hence, this study will help to further understand the genotype-phenotype associations in PAHD patients, and it may offer more reliable genetic counseling and management.
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Affiliation(s)
- Yilun Tao
- Medical Genetic Center, Changzhi Maternal and Child Health Care Hospital, 38 Weiyuanmen Road, Changzhi, Shanxi 046000, China
| | - Dong Han
- Medical Genetic Center, Changzhi Maternal and Child Health Care Hospital, 38 Weiyuanmen Road, Changzhi, Shanxi 046000, China
| | - Huiyi Shen
- Medical Genetic Center, Changzhi Maternal and Child Health Care Hospital, 38 Weiyuanmen Road, Changzhi, Shanxi 046000, China
| | - Xiaoze Li
- Medical Genetic Center, Changzhi Maternal and Child Health Care Hospital, 38 Weiyuanmen Road, Changzhi, Shanxi 046000, China.
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20
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Kaiser RA, Carlson DF, Allen KL, Webster DA, VanLith CJ, Nicolas CT, Hillin LG, Yu Y, Kaiser CW, Wahoff WR, Hickey RD, Watson AL, Winn SR, Thöny B, Kern DR, Harding CO, Lillegard JB. Development of a porcine model of phenylketonuria with a humanized R408W mutation for gene editing. PLoS One 2021; 16:e0245831. [PMID: 33493163 PMCID: PMC7833140 DOI: 10.1371/journal.pone.0245831] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 01/08/2021] [Indexed: 12/15/2022] Open
Abstract
Phenylketonuria (PKU) is a metabolic disorder whereby phenylalanine metabolism is deficient due to allelic variations in the gene for phenylalanine hydroxylase (PAH). There is no cure for PKU other than orthotopic liver transplantation, and the standard of care for patients is limited to dietary restrictions and key amino acid supplementation. Therefore, Pah was edited in pig fibroblasts for the generation of PKU clone piglets that harbor a common and severe human mutation, R408W. Additionally, the proximal region to the mutation was further humanized by introducing 5 single nucleotide polymorphisms (SNPs) to allow for development of gene editing machinery that could be translated directly from the pig model to human PKU patients that harbor at least one classic R408W allele. Resulting piglets were hypopigmented (a single Ossabaw piglet) and had low birthweight (all piglets). The piglets had similar levels of PAH expression, but no detectable enzymatic activity, consistent with the human phenotype. The piglets were fragile and required extensive neonatal care to prevent failure to thrive and early demise. Phenylalanine levels rose sharply when dietary Phe was unrestricted but could be rapidly reduced with a low Phe diet. Fibroblasts isolated from R408W piglets show susceptibility to correction using CRISPR or TALEN, with subsequent homology-directed recombination to correct Pah. This pig model of PKU provides a powerful new tool for development of all classes of therapeutic candidates to treat or cure PKU, as well as unique value for proof-of-concept studies for in vivo human gene editing platforms in the context of this humanized PKU allele.
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Affiliation(s)
- Robert A. Kaiser
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, United States of America
- Midwest Fetal Care Center, Children’s Hospitals and Clinics of Minnesota, Minneapolis, Minnesota, United States of America
| | | | - Kari L. Allen
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, United States of America
| | | | - Caitlin J. VanLith
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Clara T. Nicolas
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, United States of America
- Faculty of Medicine, University of Barcelona, Barcelona, Spain
| | - Lori G. Hillin
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Yue Yu
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Catherine W. Kaiser
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, United States of America
| | - William R. Wahoff
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Raymond D. Hickey
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Molecular Medicine, Mayo Clinic, Rochester, Minnesota, United States of America
| | | | - Shelley R. Winn
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Beat Thöny
- Department of Pediatrics, University of Zurich, Zurich, Switzerland
| | - Douglas R. Kern
- Recombinetics, Inc., St. Paul, Minnesota, United States of America
| | - Cary O. Harding
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Joseph B. Lillegard
- Department of Surgery, Mayo Clinic, Rochester, Minnesota, United States of America
- Midwest Fetal Care Center, Children’s Hospitals and Clinics of Minnesota, Minneapolis, Minnesota, United States of America
- Pediatric Surgical Associates, Minneapolis, Minnesota, United States of America
- * E-mail:
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21
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Huang YQ, Yang F, Zhu JP, Qiu JG, Li YL, Zhang L, Li HF, Zhang YL, Qin SY. Identification and characterization of a novel deletion in the phenylalanine hydroxylase gene of a Chinese patient. GENE REPORTS 2020. [DOI: 10.1016/j.genrep.2020.100819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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22
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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.
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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.
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23
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Thompson WS, Mondal G, Vanlith CJ, Kaiser RA, Lillegard JB. The future of gene-targeted therapy for hereditary tyrosinemia type 1 as a lead indication among the inborn errors of metabolism. Expert Opin Orphan Drugs 2020; 8:245-256. [PMID: 33224636 PMCID: PMC7676758 DOI: 10.1080/21678707.2020.1791082] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Introduction Inborn errors of metabolism (IEMs) often result from single-gene mutations and collectively cause liver dysfunction in neonates leading to chronic liver and systemic disease. Current treatments for many IEMs are limited to maintenance therapies that may still require orthotropic liver transplantation. Gene therapies offer a potentially superior approach by correcting or replacing defective genes with functional isoforms; however, they face unique challenges from complexities presented by individual diseases and their diverse etiology, presentation, and pathophysiology. Furthermore, immune responses, off-target gene disruption, and tumorigenesis are major concerns that need to be addressed before clinical application of gene therapy. Areas covered The current treatments for IEMs are reviewed as well as the advances in, and barriers to, gene therapy for IEMs. Attention is then given to ex vivo and in vivo gene therapy approaches for hereditary tyrosinemia type 1 (HT1). Of all IEMs, HT1 is particularly amenable to gene therapy because of a selective growth advantage conferred to corrected cells, thereby lowering the initial transduction threshold for phenotypic relevance. Expert opinion It is proposed that not only is HT1 a safe indication for gene therapy, its unique characteristics position it to be an ideal IEM to develop for clinical investigation.
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Affiliation(s)
| | - Gourish Mondal
- Department of Surgery, Research Scientist, Mayo Clinic, Rochester, MN, USA
| | | | - Robert A Kaiser
- Department of Surgery, Research Scientist, Mayo Clinic, Rochester, MN, USA.,Midwest Fetal Care Center, Childrens Hospital of Minnesota, MN, USA
| | - Joseph B Lillegard
- Midwest Fetal Care Center, Childrens Hospital of Minnesota, MN, USA.,Assistant Professor of Surgery, Mayo Clinic, Rochester, MN, USA
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24
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Levy H, Lamppu D, Anastosoaie V, Baker JL, DiBona K, Hawthorne S, Lindenberger J, Kinch D, Seymour A, McIlduff M, Watling S, Vockley J. 5-year retrospective analysis of patients with phenylketonuria (PKU) and hyperphenylalaninemia treated at two specialized clinics. Mol Genet Metab 2020; 129:177-185. [PMID: 31883647 DOI: 10.1016/j.ymgme.2019.12.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/05/2019] [Accepted: 12/08/2019] [Indexed: 11/23/2022]
Abstract
BACKGROUND Phenylketonuria (PKU) is an autosomal recessive disease caused by mutations in the PAH gene, resulting in deficiency of phenylalanine hydroxylase (PAH), an enzyme that converts phenylalanine (Phe) to tyrosine (Tyr). The purpose of this study was to capture real-world data associated with managing PKU under current standard of care and to characterize a representative population for a planned gene therapy trial. METHODS A retrospective chart review was conducted at two U.S. clinics for individuals 10-40 years old diagnosed with PKU-related hyperphenylalaninemia (HPA). Demographics, medical history, treatments and blood Phe data were collected from electronic medical records spanning a five-year period ending in November 2017. RESULTS 152 patients were enrolled (65.8% had classical PKU). Although >95% of patients were prescribed a Phe-restricted diet, blood Phe concentrations remained substantially elevated, particularly in patients diagnosed with classical PKU. As the Phe threshold was lowered (Phe < 600, 360, 120 or 30 μmol/L), the number of patients with consecutive lab values below the threshold decreased, suggesting that many patients' Phe levels are inadequately controlled. 62.5% of patients were reported as having a history of at least one neuropsychiatric comorbidity, and adults were more likely than adolescents (69.5% vs. 54.3%). 92 of 98 PAH genotypes collected were distinct mutations; the 6 null-null genotypes were associated with classical PKU. Overall the demographics and clinical data were consistent across both sites. CONCLUSION Despite dietary restrictions, mean Phe concentrations were > 360 μmol/L (a level considered well-controlled based on current U.S. treatment guidelines) for mild, moderate, and classical PKU patients. There remains an unmet need for therapies to control Phe concentrations.
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Affiliation(s)
- Harvey Levy
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | | | - Vera Anastosoaie
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - Jennifer L Baker
- Division Medical Genetics, Department of Pediatrics, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | - Kevin DiBona
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - Sarah Hawthorne
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - Jessica Lindenberger
- Division Medical Genetics, Department of Pediatrics, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA
| | | | | | - Mark McIlduff
- Boston Biomedical Associates, LLC, Marlborough, MA, USA
| | | | - Jerry Vockley
- Division Medical Genetics, Department of Pediatrics, University of Pittsburgh School of Medicine, UPMC Children's Hospital of Pittsburgh, Pittsburgh, PA, USA.
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25
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Richards DY, Winn SR, Dudley S, Nygaard S, Mighell TL, Grompe M, Harding CO. AAV-Mediated CRISPR/Cas9 Gene Editing in Murine Phenylketonuria. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2019; 17:234-245. [PMID: 31970201 PMCID: PMC6962637 DOI: 10.1016/j.omtm.2019.12.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 12/10/2019] [Indexed: 12/12/2022]
Abstract
Phenylketonuria (PKU) due to recessively inherited phenylalanine hydroxylase (PAH) deficiency results in hyperphenylalaninemia, which is toxic to the central nervous system. Restriction of dietary phenylalanine intake remains the standard of PKU care and prevents the major neurologic manifestations of the disease, yet shortcomings of dietary therapy remain, including poor adherence to a difficult and unpalatable diet, an increased incidence of neuropsychiatric illness, and imperfect neurocognitive outcomes. Gene therapy for PKU is a promising novel approach to promote lifelong neurological protection while allowing unrestricted dietary phenylalanine intake. In this study, liver-tropic recombinant AAV2/8 vectors were used to deliver CRISPR/Cas9 machinery and facilitate correction of the Pah enu2 allele by homologous recombination. Additionally, a non-homologous end joining (NHEJ) inhibitor, vanillin, was co-administered with the viral drug to promote homology-directed repair (HDR) with the AAV-provided repair template. This combinatorial drug administration allowed for lifelong, permanent correction of the Pah enu2 allele in a portion of treated hepatocytes of mice with PKU, yielding partial restoration of liver PAH activity, substantial reduction of blood phenylalanine, and prevention of maternal PKU effects during breeding. This work reveals that CRISPR/Cas9 gene editing is a promising tool for permanent PKU gene editing.
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Affiliation(s)
- Daelyn Y Richards
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Shelley R Winn
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Sandra Dudley
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Sean Nygaard
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Taylor L Mighell
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Markus Grompe
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA
| | - Cary O Harding
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, OR 97239, USA.,Department of Pediatrics, Oregon Health & Science University, Portland, OR 97239, USA
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26
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Kanavy DM, McNulty SM, Jairath MK, Brnich SE, Bizon C, Powell BC, Berg JS. Comparative analysis of functional assay evidence use by ClinGen Variant Curation Expert Panels. Genome Med 2019; 11:77. [PMID: 31783775 PMCID: PMC6884856 DOI: 10.1186/s13073-019-0683-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 11/05/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND The 2015 American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) guidelines for clinical sequence variant interpretation state that "well-established" functional studies can be used as evidence in variant classification. These guidelines articulated key attributes of functional data, including that assays should reflect the biological environment and be analytically sound; however, details of how to evaluate these attributes were left to expert judgment. The Clinical Genome Resource (ClinGen) designates Variant Curation Expert Panels (VCEPs) in specific disease areas to make gene-centric specifications to the ACMG/AMP guidelines, including more specific definitions of appropriate functional assays. We set out to evaluate the existing VCEP guidelines for functional assays. METHODS We evaluated the functional criteria (PS3/BS3) of six VCEPs (CDH1, Hearing Loss, Inherited Cardiomyopathy-MYH7, PAH, PTEN, RASopathy). We then established criteria for evaluating functional studies based on disease mechanism, general class of assay, and the characteristics of specific assay instances described in the primary literature. Using these criteria, we extensively curated assay instances cited by each VCEP in their pilot variant classification to analyze VCEP recommendations and their use in the interpretation of functional studies. RESULTS Unsurprisingly, our analysis highlighted the breadth of VCEP-approved assays, reflecting the diversity of disease mechanisms among VCEPs. We also noted substantial variability between VCEPs in the method used to select these assays and in the approach used to specify strength modifications, as well as differences in suggested validation parameters. Importantly, we observed discrepancies between the parameters VCEPs specified as required for approved assay instances and the fulfillment of these requirements in the individual assays cited in pilot variant interpretation. CONCLUSIONS Interpretation of the intricacies of functional assays often requires expert-level knowledge of the gene and disease, and current VCEP recommendations for functional assay evidence are a useful tool to improve the accessibility of functional data by providing a starting point for curators to identify approved functional assays and key metrics. However, our analysis suggests that further guidance is needed to standardize this process and ensure consistency in the application of functional evidence.
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Affiliation(s)
- Dona M Kanavy
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Shannon M McNulty
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Meera K Jairath
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sarah E Brnich
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Chris Bizon
- Renaissance Computing Institute, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Bradford C Powell
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jonathan S Berg
- Department of Genetics, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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27
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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.
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Vieira Neto E, Laranjeira F, Quelhas D, Ribeiro I, Seabra A, Mineiro N, Carvalho LM, Lacerda L, Ribeiro MG. Genotype-phenotype correlations and BH 4 estimated responsiveness in patients with phenylketonuria from Rio de Janeiro, Southeast Brazil. Mol Genet Genomic Med 2019; 7:e610. [PMID: 30829006 PMCID: PMC6503030 DOI: 10.1002/mgg3.610] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 01/15/2019] [Accepted: 01/24/2019] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Genetic heterogeneity and compound heterozygosis give rise to a continuous spectrum of phenylalanine hydroxylase deficiency and metabolic phenotypes in phenylketonuria (PKU). The most used parameters for evaluating phenotype in PKU are pretreatment phenylalanine (Phe) levels, tolerance for dietary Phe, and Phe overloading test. Phenotype can vary from a "classic" (severe) form to mild hyperphenylalaninemia, which does not require dietary treatment. A subset of patients is responsive to treatment by the cofactor tetrahydrobiopterin (BH4 ). Genotypes of PKU patients from Rio de Janeiro, Brazil, were compared to predicted and observed phenotypes. Genotype-based estimations of responsiveness to BH4 were also conducted. METHODS Phenotype was defined by pretreatment Phe levels. A standard prediction system based on arbitrary assigned values was employed to measure genotype-phenotype concordance. Patients were also estimated as BH4 -responders according to the responsiveness previously reported for their mutations and genotypes. RESULTS A 48.3% concordance rate between genotype-predicted and observed phenotypes was found. When the predicted phenotypes included those reported at the BIOPKU database, the concordance rate reached 77%. A total of 18 genotypes from 30 patients (29.4%) were estimated as of potential or probable BH4 responsiveness. Inconsistencies were observed in genotypic combinations including the common "moderate" mutations p.R261Q, p.V388M, and p.I65T and the mild mutations p.L48S, p.R68S, and p.L249F. CONCLUSION The high discordance rate between genotype-predicted and observed metabolic phenotypes in this study seems to be due partially to the high frequency of the so-called "moderate" common mutations, p.R261Q, p.V388M, and p.I65T, which are reported to be associated to erratic or more severe than expected metabolic phenotypes. Although our results of BH4 estimated responsiveness must be regarded as tentative, it should be emphasized that genotyping and genotype-phenotype association studies are important in selecting patients to be offered a BH4 overload test, especially in low-resource settings like Brazil.
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Affiliation(s)
- Eduardo Vieira Neto
- Agência Nacional de Saúde SuplementarGerência de Monitoramento AssistencialRio de JaneiroBrazil
- Serviço de Genética MédicaInstituto de Puericultura e Pediatria Martagão GesteiraUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
| | - Francisco Laranjeira
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Dulce Quelhas
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
- Unidade Multidisciplinar de Investigação BiomédicaUniversidade do PortoPortoPortugal
| | - Isaura Ribeiro
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
- Unidade Multidisciplinar de Investigação BiomédicaUniversidade do PortoPortoPortugal
| | - Alexandre Seabra
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
- Instituto de Ciências Biomédicas Abel SalazarUniversidade do PortoPortoPortugal
| | - Nicole Mineiro
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Lilian M. Carvalho
- Serviço de MetabologiaInstituto Estadual de Diabetes e Endocrinologia Luiz CapriglioneRio de JaneiroBrazil
| | - Lúcia Lacerda
- Centro de Genética Médica Doutor Jacinto MagalhãesUnidade de Bioquímica GenéticaPortoPortugal
| | - Márcia G. Ribeiro
- Serviço de Genética MédicaInstituto de Puericultura e Pediatria Martagão GesteiraUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
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29
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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.
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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
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30
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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
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