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Swanson MA, Jiang H, Busquet N, Carlsen J, Brindley C, Benke TA, Van Hove RA, Friederich MW, MacLean KN, Mesches MH, Van Hove JLK. Deep postnatal phenotyping of a new mouse model of nonketotic hyperglycinemia. J Inherit Metab Dis 2024. [PMID: 38840294 DOI: 10.1002/jimd.12755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 04/18/2024] [Accepted: 05/02/2024] [Indexed: 06/07/2024]
Abstract
Nonketotic hyperglycinemia due to deficient glycine cleavage enzyme activity causes a severe neonatal epileptic encephalopathy. Current therapies based on mitigating glycine excess have only limited impact. An animal model with postnatal phenotyping is needed to explore new therapeutic approaches. We developed a Gldc p.Ala394Val mutant model and bred it to congenic status in two colonies on C57Bl/6J (B6) and J129X1/SvJ (J129) backgrounds. Mutant mice had reduced P-protein and enzyme activity indicating a hypomorphic mutant. Glycine levels were increased in blood and brain regions, exacerbated by dietary glycine, with higher levels in female than male J129 mice. Birth defects were more prevalent in mutant B6 than J129 mice, and hydrocephalus was more frequent in B6 (40%) compared to J129 (none). The hydrocephalus rate was increased by postnatal glycine challenge in B6 mice, more so when delivered from the first neonatal week than from the fourth. Mutant mice had reduced weight gain following weaning until the eighth postnatal week, which was exacerbated by glycine loading. The electrographic spike rate was increased in mutant mice following glycine loading, but no seizures were observed. The alpha/delta band intensity ratio was decreased in the left cortex in female J129 mice, which were less active in an open field test and explored less in a Y-maze, suggesting an encephalopathic effect. Mutant mice showed no evidence of memory dysfunction. This partial recapitulation of human symptoms and biochemistry will facilitate the evaluation of new therapeutic approaches with an early postnatal time window likely most effective.
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Affiliation(s)
- Michael A Swanson
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Hua Jiang
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Nicolas Busquet
- NeuroTechnology Center, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Jessica Carlsen
- NeuroTechnology Center, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Connie Brindley
- NeuroTechnology Center, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Tim A Benke
- Department of Pediatrics, Section of Pediatric Neurology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Roxanne A Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Marisa W Friederich
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Kenneth N MacLean
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Michael H Mesches
- NeuroTechnology Center, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
- Department of Pediatrics, Section of Pediatric Neurology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Johan L K Van Hove
- Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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2
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Mikami-Saito Y, Wada Y, Arai-Ichinoi N, Nakajima Y, Suzuki-Ajihara S, Murayama K, Tanaka T, Numakura C, Hamazaki T, Igarashi N, Esaki H, Kagawa R, Kono T, Sawada T, Sawada T, Nyuzuki H, Hirai H, Fumoto S, Matsuda J, Matsunaga A, Maruyama S, Yamaguchi K, Yoshino M, Totsune E, Kikuchi A, Ohura T, Kure S. Phenotypic and genetic spectra of galactose mutarotase deficiency: A nationwide survey conducted in Japan. Genet Med 2024; 26:101165. [PMID: 38762772 DOI: 10.1016/j.gim.2024.101165] [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: 12/10/2023] [Revised: 05/10/2024] [Accepted: 05/13/2024] [Indexed: 05/20/2024] Open
Abstract
PURPOSE Galactose mutarotase (GALM) deficiency was first reported in 2019 as the fourth type of galactosemia. This study aimed to investigate the clinical and genotypic spectra of GALM deficiency. METHODS This was a questionnaire-based retrospective survey conducted in Japan between February 2022 and March 2023. RESULTS We identified 40 patients with GALM deficiency in Japan (estimated prevalence: 1:181,835). Four of 38 patients (10.5%) developed cataracts, which resolved with lactose restriction in 3 out of 4 patients. Transient transaminitis was the most common symptom (23.1%). All of the patients followed lactose restriction; discontinuation of the restriction after infancy did not cause any complications. Moreover, none of the participants experienced long-term complications. Two variants, GALM NM_138801.3: c.294del and c.424G>A, accounted for 72.5% of the identified pathogenic variants. The patients showed moderately elevated blood galactose levels with lactose intake; however, the elevation was lower than that observed in galactokinase deficiency. CONCLUSION GALM deficiency is characterized by a similar but milder phenotype and lower blood galactose elevation than in galactokinase deficiency. Diagnosis and initiation of lactose restriction in early infancy should be essential for prevention of cataracts, especially in cases of irreversible opacity.
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Affiliation(s)
- Yasuko Mikami-Saito
- Department of Pediatrics, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yoichi Wada
- Department of Pediatrics, Tohoku University Graduate School of Medicine, Sendai, Japan.
| | - Natsuko Arai-Ichinoi
- Department of Pediatrics and Child Health, Nihon University School of Medicine, Tokyo, Japan
| | - Yoko Nakajima
- Department of Pediatrics, Fujita Health University School of Medicine, Toyoake, Japan
| | - Sayaka Suzuki-Ajihara
- Department of Pediatrics and Clinical Genomics, Saitama Medical University, Saitama, Japan
| | - Kei Murayama
- Department of Metabolism, Chiba Children's Hospital, Chiba, Japan
| | - Toju Tanaka
- Department of Pediatrics, National Hospital Organization Hokkaido Medical Center, Sapporo, Japan
| | - Chikahiko Numakura
- Department of Pediatrics, Yamagata University School of Medicine, Yamagata, Japan
| | - Takashi Hamazaki
- Department of Pediatrics, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan
| | - Noboru Igarashi
- Department of Pediatrics, Toyama Prefectural Central Hospital, Toyama, Japan
| | - Hiroyuki Esaki
- Department of Pediatrics, Sasebo City General Hospital, Sasebo, Japan
| | - Reiko Kagawa
- Department of Pediatrics, Hiroshima University, Graduate School of Biomedical and Health Sciences, Hiroshima, Japan
| | - Tomotaka Kono
- Division of Endocrinology and Metabolism, Saitama Children's Medical Center, Saitama, Japan
| | - Takaaki Sawada
- Department of Pediatrics, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Tomo Sawada
- Department of Pediatrics, Izumi City General Hospital, Osaka, Japan
| | - Hiromi Nyuzuki
- Division of Pediatrics, Department of Homeostatic Regulation and Development, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Hiroki Hirai
- Department of Pediatrics, Shikoku Central Hospital of the Mutual Aid Association of Public School Teachers, Shikokuchuo, Japan
| | - Seiko Fumoto
- Department of Pediatrics, Kyorin University School of Medicine, Mitaka, Japan
| | - Junko Matsuda
- Department of Pathophysiology and Metabolism, Kawasaki Medical School, Kurashiki, Japan
| | - Ayako Matsunaga
- Department of Pediatrics, St. Marianna University School of Medicine, Kawasaki, Japan
| | - Shinsuke Maruyama
- Department of Pediatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan
| | - Kenichiro Yamaguchi
- Department of Pediatrics, National Hospital Organization Kokura Medical Center, Kitakyushu, Japan
| | - Miwa Yoshino
- Department of Pediatrics, Kyushu Hospital, Japan Community Healthcare Organization, Kitakyushu, Japan
| | - Eriko Totsune
- Department of Pediatrics, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Atsuo Kikuchi
- Department of Pediatrics, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Toshihiro Ohura
- Division of Clinical Laboratory, Sendai City Hospital, Sendai, Japan
| | - Shigeo Kure
- Department of Pediatrics, Tohoku University Graduate School of Medicine, Sendai, Japan
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3
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Swanson MA, Jiang H, Busquet N, Carlsen J, Brindley C, Benke TA, Van Hove RA, Friederich MW, MacLean KN, Mesches MH, Van Hove JLK. Deep postnatal phenotyping of a new mouse model of nonketotic hyperglycinemia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.26.586818. [PMID: 38586005 PMCID: PMC10996592 DOI: 10.1101/2024.03.26.586818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Nonketotic hyperglycinemia due to deficient glycine cleavage enzyme activity causes a severe neonatal epileptic encephalopathy. Current therapies based on mitigating glycine excess have only limited impact. An animal model with postnatal phenotyping is needed to explore new therapeutic approaches. We developed a Gldc p.Ala394Val mutant model and bred it to congenic status in 2 colonies on C57Bl/6J (B6) and J129X1/SvJ (J129) backgrounds. Mutant mice had reduced P-protein and enzyme activity indicating a hypomorphic mutant. Glycine levels were increased in blood and brain regions, exacerbated by dietary glycine, with higher levels in female than male J129 mice. Birth defects were more prevalent in mutant B6 than J129 mice, and hydrocephalus was more frequent in B6 (40%) compared to J129 (none). The hydrocephalus rate was increased by postnatal glycine challenge in B6 mice, more so when delivered from the first neonatal week than from the fourth. Mutant mice had reduced weight gain following weaning until the eighth postnatal week, which was exacerbated by glycine loading. The electrographic spike rate was increased in mutant mice following glycine loading, but no seizures were observed. The alpha/delta band intensity ratio was decreased in the left cortex in female J129 mice, which were less active in an open field test and explored less in a Y-maze, suggesting an encephalopathic effect. Mutant mice showed no evidence of memory dysfunction. This partial recapitulation of human symptoms and biochemistry will facilitate the evaluation of new therapeutic approaches with an early postnatal time window likely most effective. Take home message A mouse model of nonketotic hyperglycinemia is described that shows postnatal abnormalities in glycine levels, neural tube defects, body weight, electroencephalographic recordings, and in activity in young mice making it amenable for the evaluation of novel treatment interventions. Author contributions Study concept and design: JVH, MHM, NB, KNMAnimal study data: MAS, HJ, NB, MHM, JC, CBBiochemical and genetic studies: MAS, RAVH, MWFStatistical analysis: NB, JVHFirst draft writing: JVH, NB, MHMCritical rewriting: MAS, NB, MHM, TAB, JC, MWF, KNM, JVHFinal responsibility, guarantor, and communicating author: JVH. Competing interest statement The University of Colorado (JVH, MS, KNM, HJ) has the intention to file Intellectual property protection for certain biochemical treatments of NKH. Otherwise, the authors have stated that they had no interests that might be perceived as posing a conflict or bias to this subject matter. Funding support Financial support is acknowledged form the NKH Crusaders, Brodyn's Friends, Nora Jane Almany Foundation, the Dickens Family Foundation, the Lucas John Foundation, Les Petits Bourdons, Joseph's Fund, the Barnett Family, Maud & Vic Foundation, Lucy's BEElievers fund, Hope for NKH, Madi's Mission NKH fund, and from Dr. and Ms. Shaw, and the University of Colorado Foundation NKH research fund. The study was supported by a grant (CNS-X-19-103) from the University of Colorado School of Medicine and the Colorado Clinical Translational Science Institute, which is supported by NIH/NCATS Colorado CTSA Grant Number UL1 TR002535. Contents are the authors' sole responsibility and do not necessarily represent official NIH views. All funding sources had no role in the design or execution of the study, the interpretation of data, or the writing of the study. Ethics approval on Laboratory Animal Studies Mouse studies were carried out with approval from the Institutional Animal Care and Use Committee of the University of Colorado Anschutz Medical Campus (IACUC# 00413). Data sharing statement The data that support the findings of this study are available from the corresponding author upon reasonable request.
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4
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Fridovich-Keil JL, Berry GT. Pathophysiology of long-term complications in classic galactosemia: What we do and do not know. Mol Genet Metab 2022; 137:33-39. [PMID: 35882174 DOI: 10.1016/j.ymgme.2022.07.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 07/04/2022] [Accepted: 07/05/2022] [Indexed: 02/04/2023]
Abstract
Despite many decades of research involving both human subjects and model systems, the underlying pathophysiology of long-term complications in classic galactosemia (CG) remains poorly understood. In this review, intended for those already familiar with galactosemia, we focus on the big questions relating to outcomes, mechanism, and markers, drawing on relevant literature where available, attempting to navigate inconsistencies where they appear, and acknowledging gaps in knowledge where they persist.
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Affiliation(s)
| | - Gerard T Berry
- Division of Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
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5
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Patel S, Fridovich-Keil S, Rasmussen SA, Fridovich-Keil JL. DAB-quant: An open-source digital system for quantifying immunohistochemical staining with 3,3'-diaminobenzidine (DAB). PLoS One 2022; 17:e0271593. [PMID: 35857792 PMCID: PMC9299305 DOI: 10.1371/journal.pone.0271593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 07/05/2022] [Indexed: 11/18/2022] Open
Abstract
Here, we describe DAB-quant, a novel, open-source program designed to facilitate objective quantitation of immunohistochemical (IHC) signal in large numbers of tissue slides stained with 3,3'-diaminobenzidine (DAB). Scanned slides are arranged into separate folders for negative controls and test slides, respectively. Otsu's method is applied to the negative control slides to define a threshold distinguishing tissue from empty space, and all pixels deemed tissue are scored for normalized red minus blue (NRMB) color intensity. Next, a user-defined tolerance for error is applied to the negative control slides to set a NRMB threshold distinguishing stained from unstained tissue and this threshold is applied to calculate the fraction of stained tissue pixels on each test slide. Results are recorded in a spreadsheet and pseudocolor images are presented to document how each pixel was categorized. Slides can be analyzed in full, or sampled using small boxes scattered randomly and automatically across the tissue area. Quantitation of sampling boxes enables faster processing, reveals the degree of heterogeneity of signal, and enables exclusion of problem areas on a slide, if needed. This system should prove useful for a broad range of applications. The code, usage instructions, and sample data are freely and publicly available on GitHub (https://github.com/sarafridov/DAB-quant) and at protocols.io (dx.doi.org/10.17504/protocols.io.dm6gpb578lzp/v1).
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Affiliation(s)
- Sneh Patel
- Emory College, Emory University, Atlanta, GA, United States of America
| | - Sara Fridovich-Keil
- Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, CA, United States of America
| | - Shauna A. Rasmussen
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States of America
| | - Judith L. Fridovich-Keil
- Department of Human Genetics, School of Medicine, Emory University, Atlanta, GA, United States of America
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6
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Brophy ML, Stansfield JC, Ahn Y, Cheng SH, Murphy JE, Bell RD. AAV-mediated expression of galactose-1-phosphate uridyltransferase corrects defects of galactose metabolism in classic galactosemia patient fibroblasts. J Inherit Metab Dis 2022; 45:481-492. [PMID: 34918784 DOI: 10.1002/jimd.12468] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 11/22/2021] [Accepted: 12/08/2021] [Indexed: 11/10/2022]
Abstract
Classic galactosemia (CG) is a rare disorder of autosomal recessive inheritance. It is caused predominantly by point mutations as well as deletions in the gene encoding the enzyme galactose-1-phosphate uridyltransferase (GALT). The majority of the more than 350 mutations identified in the GALT gene cause a significant reduction in GALT enzyme activity resulting in the toxic buildup of galactose metabolites that in turn is associated with cellular stress and injury. Consequently, developing a therapeutic strategy that reverses both the oxidative and ER stress in CG cells may be helpful in combating this disease. Recombinant adeno-associated virus (AAV)-mediated gene therapy to restore GALT activity offers the potential to address the unmet medical needs of galactosemia patients. Here, utilizing fibroblasts derived from CG patients we demonstrated that AAV-mediated augmentation of GALT protein and activity resulted in the prevention of ER and oxidative stress. We also demonstrate that these CG patient fibroblasts exhibit reduced CD109 and TGFβRII protein levels and that these effectors of cellular homeostasis could be restored following AAV-mediated expression of GALT. Finally, we show initial in vivo proof-of-concept restoration of galactose metabolism in a GALT knockout mouse model following treatment with AAV-GALT.
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Affiliation(s)
- Megan L Brophy
- Rare Disease Research Unit, Pfizer, Inc., Cambridge, Massachusetts, USA
| | - John C Stansfield
- Early Clinical Development, Pfizer, Inc., Cambridge, Massachusetts, USA
| | - Youngwook Ahn
- Target Sciences, Pfizer, Inc., Cambridge, Massachusetts, USA
| | - Seng H Cheng
- Rare Disease Research Unit, Pfizer, Inc., Cambridge, Massachusetts, USA
| | - John E Murphy
- Rare Disease Research Unit, Pfizer, Inc., Cambridge, Massachusetts, USA
| | - Robert D Bell
- Rare Disease Research Unit, Pfizer, Inc., Cambridge, Massachusetts, USA
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7
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Daenzer JMI, Rasmussen SA, Patel S, McKenna J, Fridovich‐Keil JL. Neonatal GALT gene replacement offers metabolic and phenotypic correction through early adulthood in a rat model of classic galactosemia. J Inherit Metab Dis 2022; 45:203-214. [PMID: 34964137 PMCID: PMC8930472 DOI: 10.1002/jimd.12471] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 12/23/2021] [Accepted: 12/27/2021] [Indexed: 11/24/2022]
Abstract
Classic galactosemia (CG) results from profound deficiency of galactose-1-P uridylyltransferase (GALT). Despite early detection by newborn screening and lifelong dietary restriction of galactose, most patients grow to experience a range of long-term complications. Recently, we developed and characterized a GALT-null rat model of CG and demonstrated that AAV9-hGALT, administered by tail vein injection to neonatal pups, dramatically improved plasma, liver, and brain galactose metabolites at 2 weeks posttreatment. Here we report a time-course study of GALT restoration in rats treated as neonates with scAAV9-hGALT and harvested at 8, 14, 30, and 60 days. Cohorts of rats in the two older groups were weaned to diets containing either 1% or 3% of calories from galactose. As expected, GALT activity in all treated animals peaked early and then diminished over time, most notably in liver, ostensibly due to dilution of the nonreplicating episomal vector as transduced cells divided. All treated rats showed dramatic metabolic rescue through 1 month, and those weaned to the lower galactose diet showed continued strong metabolic rescue into adulthood (2 months). Prepubertal growth delay and cataracts were both partially rescued by treatment. Finally, we found that UDP glucose pyrophosphorylase (UGP), which offers a metabolic bypass around missing GALT, was 3-fold more active in brain samples from adult rats than from young pups, offering a possible explanation for the improved ability of older GALT-null rats to metabolize galactose. Combined, these results document promising metabolic and phenotypic efficacy of neonatal GALT gene replacement in a rat model of classic galactosemia.
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Affiliation(s)
| | - Shauna A. Rasmussen
- Department of Human GeneticsSchool of Medicine, Emory UniversityAtlantaGeorgiaUSA
| | - Sneh Patel
- Emory CollegeEmory UniversityAtlantaGeorgiaUSA
| | - James McKenna
- Department of Human GeneticsSchool of Medicine, Emory UniversityAtlantaGeorgiaUSA
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8
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Banford S, McCorvie TJ, Pey AL, Timson DJ. Galactosemia: Towards Pharmacological Chaperones. J Pers Med 2021; 11:jpm11020106. [PMID: 33562227 PMCID: PMC7914515 DOI: 10.3390/jpm11020106] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 02/02/2021] [Accepted: 02/04/2021] [Indexed: 02/07/2023] Open
Abstract
Galactosemia is a rare inherited metabolic disease resulting from mutations in the four genes which encode enzymes involved in the metabolism of galactose. The current therapy, the removal of galactose from the diet, is inadequate. Consequently, many patients suffer lifelong physical and cognitive disability. The phenotype varies from almost asymptomatic to life-threatening disability. The fundamental biochemical cause of the disease is a decrease in enzymatic activity due to failure of the affected protein to fold and/or function correctly. Many novel therapies have been proposed for the treatment of galactosemia. Often, these are designed to treat the symptoms and not the fundamental cause. Pharmacological chaperones (PC) (small molecules which correct the folding of misfolded proteins) represent an exciting potential therapy for galactosemia. In theory, they would restore enzyme function, thus preventing downstream pathological consequences. In practice, no PCs have been identified for potential application in galactosemia. Here, we review the biochemical basis of the disease, identify opportunities for the application of PCs and describe how these might be discovered. We will conclude by considering some of the clinical issues which will affect the future use of PCs in the treatment of galactosemia.
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Affiliation(s)
- Samantha Banford
- South Eastern Health and Social Care Trust, Downpatrick BT30 6RL, UK;
| | - Thomas J. McCorvie
- Structural Genomics Consortium, University of Oxford, Oxford OX3 7DQ, UK;
| | - Angel L. Pey
- Departamento de Química Física, Unidad de Excelencia de Química aplicada a Biomedicina y Medioambiente e Instituto de Biotecnología, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain;
| | - David J. Timson
- School of Pharmacy and Biomolecular Sciences, The University of Brighton, Brighton BN2 4GJ, UK
- Correspondence:
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9
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Delnoy B, Coelho AI, Rubio-Gozalbo ME. Current and Future Treatments for Classic Galactosemia. J Pers Med 2021; 11:jpm11020075. [PMID: 33525536 PMCID: PMC7911353 DOI: 10.3390/jpm11020075] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/23/2021] [Accepted: 01/24/2021] [Indexed: 02/07/2023] Open
Abstract
Type I (classic) galactosemia, galactose 1-phosphate uridylyltransferase (GALT)-deficiency is a hereditary disorder of galactose metabolism. The current therapeutic standard of care, a galactose-restricted diet, is effective in treating neonatal complications but is inadequate in preventing burdensome complications. The development of several animal models of classic galactosemia that (partly) mimic the biochemical and clinical phenotypes and the resolution of the crystal structure of GALT have provided important insights; however, precise pathophysiology remains to be elucidated. Novel therapeutic approaches currently being explored focus on several of the pathogenic factors that have been described, aiming to (i) restore GALT activity, (ii) influence the cascade of events and (iii) address the clinical picture. This review attempts to provide an overview on the latest advancements in therapy approaches.
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Affiliation(s)
- Britt Delnoy
- Department of Pediatrics, Maastricht University Medical Centre, 6229 HX Maastricht, The Netherlands; (B.D.); (A.I.C.)
- Department of Clinical Genetics, Maastricht University Medical Centre+, 6229 HX Maastricht, The Netherlands
- GROW-School for Oncology and Developmental Biology, Maastricht University, 6229 HX Maastricht, The Netherlands
| | - Ana I. Coelho
- Department of Pediatrics, Maastricht University Medical Centre, 6229 HX Maastricht, The Netherlands; (B.D.); (A.I.C.)
| | - Maria Estela Rubio-Gozalbo
- Department of Pediatrics, Maastricht University Medical Centre, 6229 HX Maastricht, The Netherlands; (B.D.); (A.I.C.)
- Department of Clinical Genetics, Maastricht University Medical Centre+, 6229 HX Maastricht, The Netherlands
- GROW-School for Oncology and Developmental Biology, Maastricht University, 6229 HX Maastricht, The Netherlands
- Correspondence: ; Tel.: +31-43-3872920
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10
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Rasmussen SA, Daenzer JM, Fridovich-Keil JL. A pilot study of neonatal GALT gene replacement using AAV9 dramatically lowers galactose metabolites in blood, liver, and brain and minimizes cataracts in GALT-null rat pups. J Inherit Metab Dis 2021; 44:272-281. [PMID: 32882063 PMCID: PMC7855732 DOI: 10.1002/jimd.12311] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 08/20/2020] [Accepted: 08/31/2020] [Indexed: 12/17/2022]
Abstract
Classic galactosemia (CG) is a rare metabolic disorder that results from profound deficiency of galactose-1-P uridylyltransferase (GALT). Despite early detection by newborn screening and rapid and lifelong dietary restriction of galactose, which is the current standard of care, most patients grow to experience a broad constellation of long-term complications. The mechanisms underlying these complications remain unclear and likely differ by tissue. Here we conducted a pilot study testing the safety and efficacy of GALT gene replacement using our recently-described GALT-null rat model for CG. Specifically, we administered AAV9.CMV.HA-hGALT to seven GALT-null rat pups via tail vein injection on day 3 of life; eight GALT-null pups injected with PBS served as the negative control, and four GALT+ heterozygous pups injected with PBS served as the positive control. All pups were returned to their nursing mothers, weighed daily, and euthanized for tissue collection 2 weeks later. Among the AAV9-injected pups in this study, we achieved GALT levels in liver ranging from 64% to 595% wild-type, and in brain ranging from 3% to 42% wild-type. In liver, brain, and blood samples from these animals we also saw a striking drop in galactose, galactitol, and gal-1P. Finally, all treated GALT-null pups showed dramatic improvement in cataracts relative to their mock-treated counterparts. Combined, these results demonstrate that GALT restoration in both liver and brain of GALT-null rats by neonatal tail vein administration using AAV9 is not only attainable but effective.
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Affiliation(s)
- Shauna A. Rasmussen
- Department of Human Genetics, Emory University School of Medicine, Emory Atlanta, GA USA
| | - Jennifer M.I. Daenzer
- Department of Human Genetics, Emory University School of Medicine, Emory Atlanta, GA USA
| | - Judith L. Fridovich-Keil
- Department of Human Genetics, Emory University School of Medicine, Emory Atlanta, GA USA
- Correspondence to: Judith L Fridovich-Keil, Department of Human Genetics, Emory University School of Medicine, Rm. 325.2 Whitehead Bldg., 615 Michael St, Atlanta, GA 30322 TEL 404-727-3924, FAX 404-727-3949,
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Rasmussen SA, Daenzer JMI, MacWilliams JA, Head ST, Williams MB, Geurts AM, Schroeder JP, Weinshenker D, Fridovich‐Keil JL. A galactose-1-phosphate uridylyltransferase-null rat model of classic galactosemia mimics relevant patient outcomes and reveals tissue-specific and longitudinal differences in galactose metabolism. J Inherit Metab Dis 2020; 43:518-528. [PMID: 31845342 PMCID: PMC7318568 DOI: 10.1002/jimd.12205] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 12/04/2019] [Accepted: 12/11/2019] [Indexed: 12/14/2022]
Abstract
Classic galactosemia (CG) is a potentially lethal inborn error of metabolism, if untreated, that results from profound deficiency of galactose-1-phosphate uridylyltransferase (GALT), the middle enzyme of the Leloir pathway of galactose metabolism. While newborn screening and rapid dietary restriction of galactose prevent or resolve the potentially lethal acute symptoms of CG, by mid-childhood, most treated patients experience significant complications. The mechanisms underlying these long-term deficits remain unclear. Here we introduce a new GALT-null rat model of CG and demonstrate that these rats display cataracts, cognitive, motor, and growth phenotypes reminiscent of patients outcomes. We further apply the GALT-null rats to test how well blood biomarkers, typically followed in patients, reflect metabolic perturbations in other, more relevant tissues. Our results document that the relative levels of galactose metabolites seen in GALT deficiency differ widely by tissue and age, and that red blood cell Gal-1P, the marker most commonly followed in patients, shows no significant association with Gal-1P in other tissues. The work reported here establishes our outbred GALT-null rats as an effective model for at least four complications characteristic of CG, and sets the stage for future studies addressing mechanism and testing the efficacy of novel candidate interventions.
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Affiliation(s)
- Shauna A. Rasmussen
- Department of Human GeneticsEmory University School of Medicine, Emory UniversityAtlantaGeorgia
| | - Jennifer M. I. Daenzer
- Department of Human GeneticsEmory University School of Medicine, Emory UniversityAtlantaGeorgia
| | - Jessica A. MacWilliams
- Department of Human GeneticsEmory University School of Medicine, Emory UniversityAtlantaGeorgia
| | - S. Taylor Head
- Rollins School of Public Health, Graduate Program in BiostatisticsEmory UniversityAtlantaGeorgia
| | - Martine B. Williams
- Department of Human GeneticsEmory University School of Medicine, Emory UniversityAtlantaGeorgia
| | - Aron M. Geurts
- Gene Editing Rat Resource CenterMedical College of WisconsinMilwaukeeWisconsin
| | - Jason P. Schroeder
- Department of Human GeneticsEmory University School of Medicine, Emory UniversityAtlantaGeorgia
| | - David Weinshenker
- Department of Human GeneticsEmory University School of Medicine, Emory UniversityAtlantaGeorgia
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