1
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Kernohan KD, Boycott KM. The expanding diagnostic toolbox for rare genetic diseases. Nat Rev Genet 2024; 25:401-415. [PMID: 38238519 DOI: 10.1038/s41576-023-00683-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2023] [Indexed: 05/23/2024]
Abstract
Genomic technologies, such as targeted, exome and short-read genome sequencing approaches, have revolutionized the care of patients with rare genetic diseases. However, more than half of patients remain without a diagnosis. Emerging approaches from research-based settings such as long-read genome sequencing and optical genome mapping hold promise for improving the identification of disease-causal genetic variants. In addition, new omic technologies that measure the transcriptome, epigenome, proteome or metabolome are showing great potential for variant interpretation. As genetic testing options rapidly expand, the clinical community needs to be mindful of their individual strengths and limitations, as well as remaining challenges, to select the appropriate diagnostic test, correctly interpret results and drive innovation to address insufficiencies. If used effectively - through truly integrative multi-omics approaches and data sharing - the resulting large quantities of data from these established and emerging technologies will greatly improve the interpretative power of genetic and genomic diagnostics for rare diseases.
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Affiliation(s)
- Kristin D Kernohan
- CHEO Research Institute, University of Ottawa, Ottawa, ON, Canada
- Newborn Screening Ontario, CHEO, Ottawa, ON, Canada
| | - Kym M Boycott
- CHEO Research Institute, University of Ottawa, Ottawa, ON, Canada.
- Department of Genetics, CHEO, Ottawa, ON, Canada.
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2
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Al Ashmar S, Anwardeen NR, Anlar GG, Pedersen S, Elrayess MA, Zeidan A. Metabolomic profiling reveals key metabolites associated with hypertension progression. Front Cardiovasc Med 2024; 11:1284114. [PMID: 38390445 PMCID: PMC10881871 DOI: 10.3389/fcvm.2024.1284114] [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: 08/28/2023] [Accepted: 01/17/2024] [Indexed: 02/24/2024] Open
Abstract
Introduction Pre-hypertension is a prevalent condition among the adult population worldwide. It is characterized by asymptomatic elevations in blood pressure beyond normal levels but not yet reaching the threshold for hypertension. If left uncontrolled, pre-hypertension can progress to hypertension, thereby increasing the risk of serious complications such as heart disease, stroke, kidney damage, and others. Objective The precise mechanisms driving the progression of hypertension remain unknown. Thus, identifying the metabolic changes associated with this condition can provide valuable insights into potential markers or pathways implicated in the development of hypertension. Methods In this study, we utilized untargeted metabolomics profiling, which examines over 1,000 metabolites to identify novel metabolites contributing to the progression from pre-hypertension to hypertension. Data were collected from 323 participants through Qatar Biobank. Results By comparing metabolic profiles between pre-hypertensive, hypertensive and normotensive individuals, six metabolites including stearidonate, hexadecadienoate, N6-carbamoylthreonyladenosine, 9 and 13-S-hydroxyoctadecadienoic acid (HODE), 2,3-dihydroxy-5-methylthio- 4-pentenoate (DMTPA), and linolenate were found to be associated with increased risk of hypertension, in both discovery and validation cohorts. Moreover, these metabolites showed a significant diagnostic performance with area under curve >0.7. Conclusion These findings suggest possible biomarkers that can predict the risk of progression from pre-hypertension to hypertension. This will aid in early detection, diagnosis, and management of this disease as well as its associated complications.
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Affiliation(s)
- Sarah Al Ashmar
- Department of Basic Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
| | | | - Gulsen Guliz Anlar
- Department of Basic Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
| | - Shona Pedersen
- Department of Basic Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
| | - Mohamed A Elrayess
- Department of Basic Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
- Biomedical Research Center, Qatar University, Doha, Qatar
| | - Asad Zeidan
- Department of Basic Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
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3
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Wurth R, Turgeon C, Stander Z, Oglesbee D. An evaluation of untargeted metabolomics methods to characterize inborn errors of metabolism. Mol Genet Metab 2024; 141:108115. [PMID: 38181458 PMCID: PMC10843816 DOI: 10.1016/j.ymgme.2023.108115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/19/2023] [Accepted: 12/12/2023] [Indexed: 01/07/2024]
Abstract
Inborn errors of metabolism (IEMs) encompass a diverse group of disorders that can be difficult to classify due to heterogenous clinical, molecular, and biochemical manifestations. Untargeted metabolomics platforms have become a popular approach to analyze IEM patient samples because of their ability to detect many metabolites at once, accelerating discovery of novel biomarkers, and metabolic mechanisms of disease. However, there are concerns about the reproducibility of untargeted metabolomics research due to the absence of uniform reporting practices, data analyses, and experimental design guidelines. Therefore, we critically evaluated published untargeted metabolomic platforms used to characterize IEMs to summarize the strengths and areas for improvement of this technology as it progresses towards the clinical laboratory. A total of 96 distinct IEMs were collectively evaluated by the included studies. However, most of these IEMs were evaluated by a single untargeted metabolomic method, in a single study, with a limited cohort size (55/96, 57%). The goals of the included studies generally fell into two, often overlapping, categories: detecting known biomarkers from many biochemically distinct IEMs using a single platform, and detecting novel metabolites or metabolic pathways. There was notable diversity in the design of the untargeted metabolomic platforms. Importantly, the majority of studies reported adherence to quality metrics, including the use of quality control samples and internal standards in their experiments, as well as confirmation of at least some of their feature annotations with commercial reference standards. Future applications of untargeted metabolomics platforms to the study of IEMs should move beyond single-subject analyses, and evaluate reproducibility using a prospective, or validation cohort.
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Affiliation(s)
- Rachel Wurth
- Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, 200 1(st) St SW, Rochester, MN 55905, USA
| | - Coleman Turgeon
- Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, USA
| | - Zinandré Stander
- Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, USA
| | - Devin Oglesbee
- Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 1st St SW, Rochester, MN 55905, USA.
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Leitner BP, Lee WD, Zhu W, Zhang X, Gaspar RC, Li Z, Rabinowitz JD, Perry RJ. Tissue-specific reprogramming of glutamine metabolism maintains tolerance to sepsis. PLoS One 2023; 18:e0286525. [PMID: 37410734 PMCID: PMC10325078 DOI: 10.1371/journal.pone.0286525] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 05/17/2023] [Indexed: 07/08/2023] Open
Abstract
Reprogramming metabolism is of great therapeutic interest for reducing morbidity and mortality during sepsis-induced critical illness. Disappointing results from randomized controlled trials targeting glutamine and antioxidant metabolism in patients with sepsis have begged a deeper understanding of the tissue-specific metabolic response to sepsis. The current study sought to fill this gap. We analyzed skeletal muscle transcriptomics of critically ill patients, versus elective surgical controls, which revealed reduced expression of genes involved in mitochondrial metabolism and electron transport, with increases in glutathione cycling, glutamine, branched chain, and aromatic amino acid transport. We then performed untargeted metabolomics and 13C isotope tracing to analyze systemic and tissue specific metabolic phenotyping in a murine polymicrobial sepsis model. We found an increased number of correlations between the metabolomes of liver, kidney, and spleen, with loss of correlations between the heart and quadriceps and all other organs, pointing to a shared metabolic signature within vital abdominal organs, and unique metabolic signatures for muscles during sepsis. A lowered GSH:GSSG and elevated AMP:ATP ratio in the liver underlie the significant upregulation of isotopically labeled glutamine's contribution to TCA cycle anaplerosis and glutamine-derived glutathione biosynthesis; meanwhile, the skeletal muscle and spleen were the only organs where glutamine's contribution to the TCA cycle was significantly suppressed. These results highlight tissue-specific mitochondrial reprogramming to support liver energetic demands and antioxidant synthesis, rather than global mitochondrial dysfunction, as a metabolic consequence of sepsis.
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Affiliation(s)
- Brooks P. Leitner
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Won D. Lee
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- Department of Chemistry, Princeton University, Princeton, New Jersey, United States of America
| | - Wanling Zhu
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Xinyi Zhang
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Rafael C. Gaspar
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Zongyu Li
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
| | - Joshua D. Rabinowitz
- Lewis Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- Department of Chemistry, Princeton University, Princeton, New Jersey, United States of America
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Ludwig Institute for Cancer Research, Princeton Branch, Princeton, New Jersey, United States of America
| | - Rachel J. Perry
- Department of Cellular & Molecular Physiology, Yale University, New Haven, Connecticut, United States of America
- Department of Internal Medicine, Yale University, New Haven, Connecticut, United States of America
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5
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Dai HD, Qiu F, Jackson K, Fruttiger M, Rizzo WB. Untargeted Metabolomic Analysis of Sjögren-Larsson Syndrome Reveals a Distinctive Pattern of Multiple Disrupted Biochemical Pathways. Metabolites 2023; 13:682. [PMID: 37367841 DOI: 10.3390/metabo13060682] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 05/13/2023] [Accepted: 05/16/2023] [Indexed: 06/28/2023] Open
Abstract
Sjögren-Larsson syndrome (SLS) is a rare inherited neurocutaneous disease characterized by ichthyosis, spastic diplegia or tetraplegia, intellectual disability and a distinctive retinopathy. SLS is caused by bi-allelic mutations in ALDH3A2, which codes for fatty aldehyde dehydrogenase (FALDH) and results in abnormal lipid metabolism. The biochemical abnormalities in SLS are not completely known, and the pathogenic mechanisms leading to symptoms are still unclear. To search for pathways that are perturbed in SLS, we performed untargeted metabolomic screening in 20 SLS subjects along with age- and sex-matched controls. Of 823 identified metabolites in plasma, 121 (14.7%) quantitatively differed in the overall SLS cohort from controls; 77 metabolites were decreased and 44 increased. Pathway analysis pointed to disrupted metabolism of sphingolipids, sterols, bile acids, glycogen, purines and certain amino acids such as tryptophan, aspartate and phenylalanine. Random forest analysis identified a unique metabolomic profile that had a predictive accuracy of 100% for discriminating SLS from controls. These results provide new insight into the abnormal biochemical pathways that likely contribute to disease in SLS and may constitute a biomarker panel for diagnosis and future therapeutic studies.
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Affiliation(s)
- Hongying Daisy Dai
- Department of Biostatistics, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Fang Qiu
- Department of Biostatistics, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | | | - Marcus Fruttiger
- UCL Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - William B Rizzo
- Department of Pediatrics and Child Health Research Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
- Children's Hospital & Medical Center, Omaha, NE 68114, USA
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6
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Slenter DN, Hemel IMGM, Evelo CT, Bierau J, Willighagen EL, Steinbusch LKM. Extending inherited metabolic disorder diagnostics with biomarker interaction visualizations. Orphanet J Rare Dis 2023; 18:95. [PMID: 37101200 PMCID: PMC10131334 DOI: 10.1186/s13023-023-02683-9] [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: 09/01/2022] [Accepted: 04/02/2023] [Indexed: 04/28/2023] Open
Abstract
BACKGROUND Inherited Metabolic Disorders (IMDs) are rare diseases where one impaired protein leads to a cascade of changes in the adjacent chemical conversions. IMDs often present with non-specific symptoms, a lack of a clear genotype-phenotype correlation, and de novo mutations, complicating diagnosis. Furthermore, products of one metabolic conversion can be the substrate of another pathway obscuring biomarker identification and causing overlapping biomarkers for different disorders. Visualization of the connections between metabolic biomarkers and the enzymes involved might aid in the diagnostic process. The goal of this study was to provide a proof-of-concept framework for integrating knowledge of metabolic interactions with real-life patient data before scaling up this approach. This framework was tested on two groups of well-studied and related metabolic pathways (the urea cycle and pyrimidine de-novo synthesis). The lessons learned from our approach will help to scale up the framework and support the diagnosis of other less-understood IMDs. METHODS Our framework integrates literature and expert knowledge into machine-readable pathway models, including relevant urine biomarkers and their interactions. The clinical data of 16 previously diagnosed patients with various pyrimidine and urea cycle disorders were visualized on the top 3 relevant pathways. Two expert laboratory scientists evaluated the resulting visualizations to derive a diagnosis. RESULTS The proof-of-concept platform resulted in varying numbers of relevant biomarkers (five to 48), pathways, and pathway interactions for each patient. The two experts reached the same conclusions for all samples with our proposed framework as with the current metabolic diagnostic pipeline. For nine patient samples, the diagnosis was made without knowledge about clinical symptoms or sex. For the remaining seven cases, four interpretations pointed in the direction of a subset of disorders, while three cases were found to be undiagnosable with the available data. Diagnosing these patients would require additional testing besides biochemical analysis. CONCLUSION The presented framework shows how metabolic interaction knowledge can be integrated with clinical data in one visualization, which can be relevant for future analysis of difficult patient cases and untargeted metabolomics data. Several challenges were identified during the development of this framework, which should be resolved before this approach can be scaled up and implemented to support the diagnosis of other (less understood) IMDs. The framework could be extended with other OMICS data (e.g. genomics, transcriptomics), and phenotypic data, as well as linked to other knowledge captured as Linked Open Data.
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Affiliation(s)
- Denise N Slenter
- Department of Bioinformatics (BiGCaT), NUTRIM, Maastricht University, Maastricht, The Netherlands.
| | - Irene M G M Hemel
- Department of Bioinformatics (BiGCaT), NUTRIM, Maastricht University, Maastricht, The Netherlands
- Maastricht Centre for Systems Biology (MaCSBio), Maastricht University, Maastricht, The Netherlands
| | - Chris T Evelo
- Department of Bioinformatics (BiGCaT), NUTRIM, Maastricht University, Maastricht, The Netherlands
- Maastricht Centre for Systems Biology (MaCSBio), Maastricht University, Maastricht, The Netherlands
| | - Jörgen Bierau
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Egon L Willighagen
- Department of Bioinformatics (BiGCaT), NUTRIM, Maastricht University, Maastricht, The Netherlands
| | - Laura K M Steinbusch
- Department of Clinical Genetics, Maastricht University Medical Center, Maastricht, The Netherlands
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7
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Mak J, Peng G, Le A, Gandotra N, Enns GM, Scharfe C, Cowan TM. Validation of a targeted metabolomics panel for improved second-tier newborn screening. J Inherit Metab Dis 2023; 46:194-205. [PMID: 36680545 PMCID: PMC10023470 DOI: 10.1002/jimd.12591] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/18/2023] [Accepted: 01/19/2023] [Indexed: 01/22/2023]
Abstract
Improved second-tier assays are needed to reduce the number of false positives in newborn screening (NBS) for inherited metabolic disorders including those on the Recommended Uniform Screening Panel (RUSP). We developed an expanded metabolite panel for second-tier testing of dried blood spot (DBS) samples from screen-positive cases reported by the California NBS program, consisting of true- and false-positives from four disorders: glutaric acidemia type I (GA1), methylmalonic acidemia (MMA), ornithine transcarbamylase deficiency (OTCD), and very long-chain acyl-CoA dehydrogenase deficiency (VLCADD). This panel was assembled from known disease markers and new features discovered by untargeted metabolomics and applied to second-tier analysis of single DBS punches using liquid chromatography-tandem mass spectrometry (LC-MS/MS) in a 3-min run. Additionally, we trained a Random Forest (RF) machine learning classifier to improve separation of true- and false positive cases. Targeted metabolomic analysis of 121 analytes from DBS extracts in combination with RF classification at a sensitivity of 100% reduced false positives for GA1 by 83%, MMA by 84%, OTCD by 100%, and VLCADD by 51%. This performance was driven by a combination of known disease markers (3-hydroxyglutaric acid, methylmalonic acid, citrulline, and C14:1), other amino acids and acylcarnitines, and novel metabolites identified to be isobaric to several long-chain acylcarnitine and hydroxy-acylcarnitine species. These findings establish the effectiveness of this second-tier test to improve screening for these four conditions and demonstrate the utility of supervised machine learning in reducing false-positives for conditions lacking clearly discriminating markers, with future studies aimed at optimizing and expanding the panel to additional disease targets.
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Affiliation(s)
- Justin Mak
- Clinical Biochemical Genetics Laboratory, Stanford Health Care, Stanford, CA, USA
| | - Gang Peng
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
- Department of Biostatistics, Yale University School of Public Health, New Haven, CT, USA
| | - Anthony Le
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
| | - Neeru Gandotra
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Gregory M. Enns
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - Curt Scharfe
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Tina M. Cowan
- Clinical Biochemical Genetics Laboratory, Stanford Health Care, Stanford, CA, USA
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, USA
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8
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Metabolomics Differences of the Donor Livers Between In Situ and Ex Situ Conditions During Ischemia-free Liver Transplantation. Transplantation 2023; 107:e139-e151. [PMID: 36857152 PMCID: PMC10125122 DOI: 10.1097/tp.0000000000004529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023]
Abstract
BACKGROUND Ischemia-free liver transplantation (IFLT) has been innovated to avoid graft ischemia during organ procurement, preservation, and implantation. However, the metabolism activity of the donor livers between in the in situ and ex situ normothermic machine perfusion (NMP) conditions, and between standard criteria donor and extend criteria donor remains unknown. METHODS During IFLT, plasma samples were collected both at the portal vein and hepatic vein of the donor livers in situ during procurement and ex situ during NMP. An ultra-high performance liquid chromatography-mass spectrometry was conducted to investigate the common and distinct intraliver metabolite exchange. RESULTS Profound cysteine and methionine metabolism, and aminoacyl-tRNA biosynthesis were found in both in situ and ex situ conditions. However, obvious D-arginine and D-ornithine metabolism, arginine and proline metabolism were only found in the in situ condition. The suppressed activities of the urea cycle pathway during ex situ condition were confirmed in an RNA expression level. In addition, compared with extend criteria donor group, standard criteria donor group had more active intraliver metabolite exchange in metabonomics level. Furthermore, we found that the relative concentration of p-cresol, allocystathionine, L-prolyl-L-proline in the ex situ group was strongly correlated with peak alanine aminotransferase and aspartate aminotransferase at postoperative days 1-7. CONCLUSIONS In the current study, we show the common and distinct metabolism activities during IFLT. These findings might provide insights on how to modify the design of NMP device, improve the perfusate components, and redefine the criteria of graft viability.
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Hertzog A, Selvanathan A, Devanapalli B, Ho G, Bhattacharya K, Tolun AA. A narrative review of metabolomics in the era of "-omics": integration into clinical practice for inborn errors of metabolism. Transl Pediatr 2022; 11:1704-1716. [PMID: 36345452 PMCID: PMC9636448 DOI: 10.21037/tp-22-105] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Accepted: 08/23/2022] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND OBJECTIVE Traditional targeted metabolomic investigations identify a pre-defined list of analytes in samples and have been widely used for decades in the diagnosis and monitoring of inborn errors of metabolism (IEMs). Recent technological advances have resulted in the development and maturation of untargeted metabolomics: a holistic, unbiased, analytical approach to detecting metabolic disturbances in human disease. We aim to provide a summary of untargeted metabolomics [focusing on tandem mass spectrometry (MS-MS)] and its application in the field of IEMs. METHODS Data for this review was identified through a literature search using PubMed, Google Scholar, and personal repositories of articles collected by the authors. Findings are presented within several sections describing the metabolome, the current use of targeted metabolomics in the diagnostic pathway of patients with IEMs, the more recent integration of untargeted metabolomics into clinical care, and the limitations of this newly employed analytical technique. KEY CONTENT AND FINDINGS Untargeted metabolomic investigations are increasingly utilized in screening for rare disorders, improving understanding of cellular and subcellular physiology, discovering novel biomarkers, monitoring therapy, and functionally validating genomic variants. Although the untargeted metabolomic approach has some limitations, this "next generation metabolic screening" platform is becoming increasingly affordable and accessible. CONCLUSIONS When used in conjunction with genomics and the other promising "-omic" technologies, untargeted metabolomics has the potential to revolutionize the diagnostics of IEMs (and other rare disorders), improving both clinical and health economic outcomes.
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Affiliation(s)
- Ashley Hertzog
- NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Arthavan Selvanathan
- Genetic Metabolic Disorders Service, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Beena Devanapalli
- NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, NSW, Australia
| | - Gladys Ho
- Sydney Genome Diagnostics, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Specialty of Genomic Medicine, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Kaustuv Bhattacharya
- Genetic Metabolic Disorders Service, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Specialty of Genomic Medicine, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
| | - Adviye Ayper Tolun
- NSW Biochemical Genetics Service, The Children's Hospital at Westmead, Westmead, NSW, Australia.,Specialty of Genomic Medicine, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
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10
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Bin Sawad A, Jackimiec J, Bechter M, Trucillo A, Lindsley K, Bhagat A, Uyei J, Diaz GA. Epidemiology, methods of diagnosis, and clinical management of patients with arginase 1 deficiency (ARG1-D): A systematic review. Mol Genet Metab 2022; 137:153-163. [PMID: 36049366 DOI: 10.1016/j.ymgme.2022.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/18/2022] [Accepted: 08/20/2022] [Indexed: 11/19/2022]
Abstract
BACKGROUND Arginase 1 Deficiency (ARG1-D) is a rare, progressive, metabolic disorder that is characterized by devastating manifestations driven by elevated plasma arginine levels. It typically presents in early childhood with spasticity (predominately affecting the lower limbs), mobility impairment, seizures, developmental delay, and intellectual disability. This systematic review aims to identify and describe the published evidence outlining the epidemiology, diagnosis methods, measures of disease progression, clinical management, and outcomes for ARG1-D patients. METHODS A comprehensive literature search across multiple databases such as MEDLINE, Embase, and a review of clinical studies in ClinicalTrials.gov (with results reported) was carried out per PRISMA guidelines on 20 April 2020 with no date restriction. Pre-defined eligibility criteria were used to identify studies with data specific to patients with ARG1-D. Two independent reviewers screened records and extracted data from included studies. Quality was assessed using the modified Newcastle-Ottawa Scale for non-comparative studies. RESULTS Overall, 55 records reporting 40 completed studies and 3 ongoing studies were included. Ten studies reported the prevalence of ARG1-D in the general population, with a median of 1 in 1,000,000. Frequently reported diagnostic methods included genetic testing, plasma arginine levels, and red blood cell arginase activity. However, routine newborn screening is not universally available, and lack of disease awareness may prevent early diagnosis or lead to misdiagnosis, as the disease has overlapping symptomology with other diseases, such as cerebral palsy. Common manifestations reported at time of diagnosis and assessed for disease progression included spasticity (predominately affecting the lower limbs), mobility impairment, developmental delay, intellectual disability, and seizures. Severe dietary protein restriction, essential amino acid supplementation, and nitrogen scavenger administration were the most commonly reported treatments among patients with ARG1-D. Only a few studies reported meaningful clinical outcomes of these interventions on intellectual disability, motor function and adaptive behavior assessment, hospitalization, or death. The overall quality of included studies was assessed as good according to the Newcastle-Ottawa Scale. CONCLUSIONS Although ARG1-D is a rare disease, published evidence demonstrates a high burden of disease for patients. The current standard of care is ineffective at preventing disease progression. There remains a clear need for new treatment options as well as improved access to diagnostics and disease awareness to detect and initiate treatment before the onset of clinical manifestations to potentially enable more normal development, improve symptomatology, or prevent disease progression.
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Affiliation(s)
| | | | | | | | | | | | | | - George A Diaz
- Division of Medical Genetics and Genomics in the Department of Genetics and Genomic Sciences at the Icahn School of Medicine at Mount Sinai, New York, NY, USA
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11
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Baros-Steyl SS, Al Heialy S, Semreen AH, Semreen MH, Blackburn JM, Soares NC. A review of mass spectrometry-based analyses to understand COVID-19 convalescent plasma mechanisms of action. Proteomics 2022; 22:e2200118. [PMID: 35809024 PMCID: PMC9349457 DOI: 10.1002/pmic.202200118] [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: 03/21/2022] [Revised: 07/04/2022] [Accepted: 07/05/2022] [Indexed: 01/08/2023]
Abstract
The spread of coronavirus disease 2019 (COVID‐19) viral pneumonia caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has become a worldwide pandemic claiming several thousands of lives worldwide. During this pandemic, several studies reported the use of COVID‐19 convalescent plasma (CCP) from recovered patients to treat severely or critically ill patients. Although this historical and empirical treatment holds immense potential as a first line of response against eventual future unforeseen viral epidemics, there are several concerns regarding the efficacy and safety of this approach. This critical review aims to pinpoint the possible role of mass spectrometry‐based analysis in the identification of unique molecular component proteins, peptides, and metabolites of CCP that explains the therapeutic mechanism of action against COVID‐19. Additionally, the text critically reviews the potential application of mass spectrometry approaches in the search for novel plasma biomarkers that may enable a rapid and accurate assessment of the safety and efficacy of CCP. Considering the relative low‐cost value involved in the CCP therapy, this proposed line of research represents a tangible scientific challenge that will be translated into clinical practice and help save several thousand lives around the world, specifically in low‐ and middle‐income countries.
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Affiliation(s)
- Seanantha S Baros-Steyl
- Department of Integrative Biomedical Sciences, Institute of Infectious Disease & Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Saba Al Heialy
- College of Medicine, Mohammed Bin Rashid University of Medicine and Health Sciences, Dubai, United Arab Emirates.,Meakin-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Ahlam H Semreen
- College of Pharmacy-Department of Medicinal Chemistry, University of Sharjah, United Arab Emirates.,Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Mohammad H Semreen
- College of Pharmacy-Department of Medicinal Chemistry, University of Sharjah, United Arab Emirates.,Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Jonathan M Blackburn
- Department of Integrative Biomedical Sciences, Institute of Infectious Disease & Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Nelson C Soares
- College of Pharmacy-Department of Medicinal Chemistry, University of Sharjah, United Arab Emirates.,Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
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12
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Dobrowolski SF, Phua YL, Sudano C, Spridik K, Zinn PO, Wang Y, Bharathi S, Vockley J, Goetzman E. Comparative metabolomics in the Pah enu2 classical PKU mouse identifies cerebral energy pathway disruption and oxidative stress. Mol Genet Metab 2022; 136:38-45. [PMID: 35367142 PMCID: PMC9759961 DOI: 10.1016/j.ymgme.2022.03.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 03/08/2022] [Indexed: 01/06/2023]
Abstract
Classical phenylketonuria (PKU, OMIM 261600) owes to hepatic deficiency of phenylalanine hydroxylase (PAH) that enzymatically converts phenylalanine (Phe) to tyrosine (Tyr). PKU neurologic phenotypes include impaired brain development, decreased myelination, early onset mental retardation, seizures, and late-onset features (neuropsychiatric, Parkinsonism). Phe over-representation is systemic; however, tissue response to hyperphenylalaninemia is not consistent. To characterize hyperphenylalaninemia tissue response, metabolomics was applied to Pahenu2 classical PKU mouse blood, liver, and brain. In blood and liver over-represented analytes were principally Phe, Phe catabolites, and Phe-related analytes (Phe-conjugates, Phe-containing dipeptides). In addition to Phe and Phe-related analytes, the metabolomic profile of Pahenu2 brain tissue evidenced oxidative stress responses and energy dysregulation. Glutathione and homocarnosine anti-oxidative responses are apparent Pahenu2 brain. Oxidative stress in Pahenu2 brain was further evidenced by increased reactive oxygen species. Pahenu2 brain presents an increased NADH/NAD ratio suggesting respiratory chain complex 1 dysfunction. Respirometry in Pahenu2 brain mitochondria functionally confirmed reduced respiratory chain activity with an attenuated response to pyruvate substrate. Glycolysis pathway analytes are over-represented in Pahenu2 brain tissue. PKU pathologies owe to liver metabolic deficiency; yet, Pahenu2 liver tissue shows neither energy disruption nor anti-oxidative response. Unique aspects of metabolomic homeostasis in PKU brain tissue along with increased reactive oxygen species and respiratory chain deficit provide insight to neurologic disease mechanisms. While some elements of assumed, long standing PKU neuropathology are enforced by metabolomic data (e.g. reduced tryptophan and serotonin representation), energy dysregulation and tissue oxidative stress expand mechanisms underlying neuropathology.
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Affiliation(s)
- Steven F Dobrowolski
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States of America.
| | - Yu Leng Phua
- Division of Medical Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States of America
| | - Cayla Sudano
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States of America
| | - Kayla Spridik
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States of America
| | - Pascal O Zinn
- Department of Neurological Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States of America
| | - Yudong Wang
- Division of Medical Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States of America
| | - Sivakama Bharathi
- Division of Medical Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States of America
| | - Jerry Vockley
- Division of Medical Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States of America
| | - Eric Goetzman
- Division of Medical Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States of America
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13
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Understanding Inborn Errors of Metabolism through Metabolomics. Metabolites 2022; 12:metabo12050398. [PMID: 35629902 PMCID: PMC9143820 DOI: 10.3390/metabo12050398] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/14/2022] [Accepted: 04/25/2022] [Indexed: 12/10/2022] Open
Abstract
Inborn errors of metabolism (IEMs) are rare diseases caused by a defect in a single enzyme, co-factor, or transport protein. For most IEMs, no effective treatment is available and the exact disease mechanism is unknown. The application of metabolomics and, more specifically, tracer metabolomics in IEM research can help to elucidate these disease mechanisms and hence direct novel therapeutic interventions. In this review, we will describe the different approaches to metabolomics in IEM research. We will discuss the strengths and weaknesses of the different sample types that can be used (biofluids, tissues or cells from model organisms; modified cell lines; and patient fibroblasts) and when each of them is appropriate to use.
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14
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Thistlethwaite LR, Li X, Burrage LC, Riehle K, Hacia JG, Braverman N, Wangler MF, Miller MJ, Elsea SH, Milosavljevic A. Clinical diagnosis of metabolic disorders using untargeted metabolomic profiling and disease-specific networks learned from profiling data. Sci Rep 2022; 12:6556. [PMID: 35449147 PMCID: PMC9023513 DOI: 10.1038/s41598-022-10415-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 03/14/2022] [Indexed: 02/06/2023] Open
Abstract
Untargeted metabolomics is a global molecular profiling technology that can be used to screen for inborn errors of metabolism (IEMs). Metabolite perturbations are evaluated based on current knowledge of specific metabolic pathway deficiencies, a manual diagnostic process that is qualitative, has limited scalability, and is not equipped to learn from accumulating clinical data. Our purpose was to improve upon manual diagnosis of IEMs in the clinic by developing novel computational methods for analyzing untargeted metabolomics data. We employed CTD, an automated computational diagnostic method that "connects the dots" between metabolite perturbations observed in individual metabolomics profiling data and modules identified in disease-specific metabolite co-perturbation networks learned from prior profiling data. We also extended CTD to calculate distances between any two individuals (CTDncd) and between an individual and a disease state (CTDdm), to provide additional network-quantified predictors for use in diagnosis. We show that across 539 plasma samples, CTD-based network-quantified measures can reproduce accurate diagnosis of 16 different IEMs, including adenylosuccinase deficiency, argininemia, argininosuccinic aciduria, aromatic L-amino acid decarboxylase deficiency, cerebral creatine deficiency syndrome type 2, citrullinemia, cobalamin biosynthesis defect, GABA-transaminase deficiency, glutaric acidemia type 1, maple syrup urine disease, methylmalonic aciduria, ornithine transcarbamylase deficiency, phenylketonuria, propionic acidemia, rhizomelic chondrodysplasia punctata, and the Zellweger spectrum disorders. Our approach can be used to supplement information from biochemical pathways and has the potential to significantly enhance the interpretation of variants of uncertain significance uncovered by exome sequencing. CTD, CTDdm, and CTDncd can serve as an essential toolset for biological interpretation of untargeted metabolomics data that overcomes limitations associated with manual diagnosis to assist diagnosticians in clinical decision-making. By automating and quantifying the interpretation of perturbation patterns, CTD can improve the speed and confidence by which clinical laboratory directors make diagnostic and treatment decisions, while automatically improving performance with new case data.
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Affiliation(s)
- Lillian R Thistlethwaite
- Quantitative and Computational Biosciences Program, Baylor College of Medicine, One Baylor Plaza, 400D, Houston, TX, 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Xiqi Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Lindsay C Burrage
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Texas Children's Hospital, Houston, TX, USA
| | - Kevin Riehle
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Joseph G Hacia
- Department of Biochemistry and Molecular Medicine, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Nancy Braverman
- Department of Pediatrics and Human Genetics, McGill University, Montreal, QC, Canada
| | - Michael F Wangler
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Texas Children's Hospital, Houston, TX, USA
- Jan and Dan Duncan Texas Children's Hospital Neurological Research Institute, Houston, TX, USA
| | - Marcus J Miller
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Sarah H Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Aleksandar Milosavljevic
- Quantitative and Computational Biosciences Program, Baylor College of Medicine, One Baylor Plaza, 400D, Houston, TX, 77030, USA.
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
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15
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Milosavljevic S, Glinton KE, Li X, Medeiros C, Gillespie P, Seavitt JR, Graham BH, Elsea SH. Untargeted Metabolomics of Slc13a5 Deficiency Reveal Critical Liver-Brain Axis for Lipid Homeostasis. Metabolites 2022; 12:metabo12040351. [PMID: 35448538 PMCID: PMC9032242 DOI: 10.3390/metabo12040351] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 03/29/2022] [Accepted: 04/03/2022] [Indexed: 01/17/2023] Open
Abstract
Though biallelic variants in SLC13A5 are known to cause severe encephalopathy, the mechanism of this disease is poorly understood. SLC13A5 protein deficiency reduces citrate transport into the cell. Downstream abnormalities in fatty acid synthesis and energy generation have been described, though biochemical signs of these perturbations are inconsistent across SLC13A5 deficiency patients. To investigate SLC13A5-related disorders, we performed untargeted metabolic analyses on the liver, brain, and serum from a Slc13a5-deficient mouse model. Metabolomic data were analyzed using the connect-the-dots (CTD) methodology and were compared to plasma and CSF metabolomics from SLC13A5-deficient patients. Mice homozygous for the Slc13a5tm1b/tm1b null allele had perturbations in fatty acids, bile acids, and energy metabolites in all tissues examined. Further analyses demonstrated that for several of these molecules, the ratio of their relative tissue concentrations differed widely in the knockout mouse, suggesting that deficiency of Slc13a5 impacts the biosynthesis and flux of metabolites between tissues. Similar findings were observed in patient biofluids, indicating altered transport and/or flux of molecules involved in energy, fatty acid, nucleotide, and bile acid metabolism. Deficiency of SLC13A5 likely causes a broader state of metabolic dysregulation than previously recognized, particularly regarding lipid synthesis, storage, and metabolism, supporting SLC13A5 deficiency as a lipid disorder.
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Affiliation(s)
- Sofia Milosavljevic
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; (S.M.); (K.E.G.); (X.L.); (J.R.S.)
- Harvard Medical School, Boston, MA 02215, USA
| | - Kevin E. Glinton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; (S.M.); (K.E.G.); (X.L.); (J.R.S.)
| | - Xiqi Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; (S.M.); (K.E.G.); (X.L.); (J.R.S.)
| | - Cláudia Medeiros
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (C.M.); (P.G.); (B.H.G.)
| | - Patrick Gillespie
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (C.M.); (P.G.); (B.H.G.)
| | - John R. Seavitt
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; (S.M.); (K.E.G.); (X.L.); (J.R.S.)
| | - Brett H. Graham
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA; (C.M.); (P.G.); (B.H.G.)
| | - Sarah H. Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; (S.M.); (K.E.G.); (X.L.); (J.R.S.)
- Correspondence: ; Tel.: +1-713-798-5484
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16
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Cui B, Wei L, Sun LY, Qu W, Zeng ZG, Liu Y, Zhu ZJ. The effect of liver transplantation for argininemia-the largest experiences in a single center. Transl Pediatr 2022; 11:495-504. [PMID: 35558983 PMCID: PMC9085954 DOI: 10.21037/tp-21-576] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 01/27/2022] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Argininemia, a rare urea cycle disorder resulting from an arginase-1 deficiency, is characterized by a progressive spastic paraplegia. While advances in diagnosis and treatment have increased the management of this condition, not all symptoms are resolved in response to traditional therapies. Interestingly, there exist some rare reports on the use of liver transplantation (LT) for the treatment of argininemia. METHODS We conducted a retrospective study of eleven patients with argininemia receiving a LT as performed at our center over the period from January 2015 to November 2019. These patients were included due to their poor responses to protein restriction diets and alternative therapies of nitrogen scavengers. Detailed information on coagulation, liver function, histopathological and morphological examination of liver samples, and other clinical presentations were extracted from these patients. A grading scale was used for evaluating the neurological status, classification of physical growth and quality of life of these patients in response to the LT. RESULTS Prior to LT, high levels of arginine were detected in all of argininemia patients and liver enzymes were elevated in nine of those patients. Nine patients presented with coagulation dysfunction without bleeding symptoms. Spastic paraplegia, irritability, intellectual developmental disability, and growth deficits were hallmarks of these nine patients, while four patients showed repeated, generalized tonic-clonic seizures before the operation. Seven novel mutations were found in these patients. The indication for LT in this series of patients was a presentation of progressive neurological impairments. After LT, the coagulation index and plasma arginine levels returned to normal and episodes of seizure were controlled in four patients. To date, all patients have survived and their LT has resulted a restoration of arginine metabolism and liver function, along with preventing further neurological deterioration, all of which provided an opportunity for future recuperation. Overall, the neurological status, growth deficits and quality of life were all significantly improved after LT with no evidence of severe complications. CONCLUSIONS LT can serve as an effective treatment for argininemia in patients who respond poorly to traditional therapy. An early intervention of LT should be conducted in these patients to prevent neurological damage and improve their quality of life.
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Affiliation(s)
- Bin Cui
- Liver Transplantation Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China.,Clinical Center for Pediatric Liver Transplantation, Capital Medical University, Beijing, China.,National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Lin Wei
- Liver Transplantation Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China.,Clinical Center for Pediatric Liver Transplantation, Capital Medical University, Beijing, China.,National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Li-Ying Sun
- Liver Transplantation Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China.,Clinical Center for Pediatric Liver Transplantation, Capital Medical University, Beijing, China.,National Clinical Research Center for Digestive Diseases, Beijing, China.,Department of Critical Liver Diseases, Liver Research Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Wei Qu
- Liver Transplantation Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China.,Clinical Center for Pediatric Liver Transplantation, Capital Medical University, Beijing, China.,National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Zhi-Gui Zeng
- Liver Transplantation Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China.,Clinical Center for Pediatric Liver Transplantation, Capital Medical University, Beijing, China.,National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Ying Liu
- Liver Transplantation Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China.,Clinical Center for Pediatric Liver Transplantation, Capital Medical University, Beijing, China.,National Clinical Research Center for Digestive Diseases, Beijing, China
| | - Zhi-Jun Zhu
- Liver Transplantation Center, Beijing Friendship Hospital, Capital Medical University, Beijing, China.,Clinical Center for Pediatric Liver Transplantation, Capital Medical University, Beijing, China.,National Clinical Research Center for Digestive Diseases, Beijing, China
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17
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Ford L, Mitchell M, Wulff J, Evans A, Kennedy A, Elsea S, Wittmann B, Toal D. Clinical metabolomics for inborn errors of metabolism. Adv Clin Chem 2022; 107:79-138. [PMID: 35337606 DOI: 10.1016/bs.acc.2021.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Metabolism is a highly regulated process that provides nutrients to cells and essential building blocks for the synthesis of protein, DNA and other macromolecules. In healthy biological systems, metabolism maintains a steady state in which the concentrations of metabolites are relatively constant yet are subject to metabolic demands and environmental stimuli. Rare genetic disorders, such as inborn errors of metabolism (IEM), cause defects in regulatory enzymes or proteins leading to metabolic pathway disruption and metabolite accumulation or deficiency. Traditionally, the laboratory diagnosis of IEMs has been limited to analytical methods that target specific metabolites such as amino acids and acyl carnitines. This approach is effective as a screening method for the most common IEM disorders but lacks the comprehensive coverage of metabolites that is necessary to identify rare disorders that present with nonspecific clinical symptoms. Fortunately, advancements in technology and data analytics has introduced a new field of study called metabolomics which has allowed scientists to perform comprehensive metabolite profiling of biological systems to provide insight into mechanism of action and gene function. Since metabolomics seeks to measure all small molecule metabolites in a biological specimen, it provides an innovative approach to evaluating disease in patients with rare genetic disorders. In this review we provide insight into the appropriate application of metabolomics in clinical settings. We discuss the advantages and limitations of the method and provide details related to the technology, data analytics and statistical modeling required for metabolomic profiling of patients with IEMs.
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Affiliation(s)
- Lisa Ford
- Metabolon, Inc., Morrisville, NC, United States
| | | | - Jacob Wulff
- Metabolon, Inc., Morrisville, NC, United States
| | - Annie Evans
- Metabolon, Inc., Morrisville, NC, United States
| | | | - Sarah Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | | | - Douglas Toal
- Metabolon, Inc., Morrisville, NC, United States.
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18
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Mill J, Patel V, Okonkwo O, Li L, Raife T. Erythrocyte sphingolipid species as biomarkers of Alzheimer's disease. J Pharm Anal 2022; 12:178-185. [PMID: 35573876 PMCID: PMC9073235 DOI: 10.1016/j.jpha.2021.07.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 06/08/2021] [Accepted: 07/13/2021] [Indexed: 01/25/2023] Open
Abstract
Diagnosing Alzheimer's disease (AD) in the early stage is challenging. Informative biomarkers can be of great value for population-based screening. Metabolomics studies have been used to find potential biomarkers, but commonly used tissue sources can be difficult to obtain. The objective of this study was to determine the potential utility of erythrocyte metabolite profiles in screening for AD. Unlike some commonly-used sources such as cerebrospinal fluid and brain tissue, erythrocytes are plentiful and easily accessed. Moreover, erythrocytes are metabolically active, a feature that distinguishes this sample source from other bodily fluids like plasma and urine. In this preliminary pilot study, the erythrocyte metabolomes of 10 histopathologically confirmed AD patients and 10 patients without AD (control (CTRL)) were compared. Whole blood was collected post-mortem and erythrocytes were analyzed using ultra-performance liquid chromatography tandem mass spectrometry. Over 750 metabolites were identified in AD and CTRL erythrocytes. Seven were increased in AD while 24 were decreased (P<0.05). The majority of the metabolites increased in AD were associated with amino acid metabolism and all of the decreased metabolites were associated with lipid metabolism. Prominent among the potential biomarkers were 10 sphingolipid or sphingolipid-related species that were consistently decreased in AD patients. Sphingolipids have been previously implicated in AD and other neurological conditions. Furthermore, previous studies have shown that erythrocyte sphingolipid concentrations vary widely in normal, healthy adults. Together, these observations suggest that certain erythrocyte lipid phenotypes could be markers of risk for development of AD.
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Affiliation(s)
- Jericha Mill
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Vihar Patel
- Department of Pathology and Laboratory Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, 53705, USA
| | - Ozioma Okonkwo
- Clinical Science Center, Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, Madison, WI, 53792, USA
| | - Lingjun Li
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Corresponding author. School of Pharmacy and Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53705, USA.
| | - Thomas Raife
- Department of Pathology and Laboratory Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, 53705, USA
- Corresponding author.
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19
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Yang P, Zhou L, Chen M, Zeng L, Ouyang Y, Zheng X, Chen X, Yang Z, Tian Z. Supplementation of amino acids and organic acids prevents the increase in blood pressure induced by high salt in Dahl salt-sensitive rats. Food Funct 2022; 13:891-903. [PMID: 34994761 DOI: 10.1039/d1fo03577k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A high-salt (HS) diet leads to metabolic disorders in Dahl salt-sensitive (SS) rats, and promotes the development of hypertension. According to the changes in the metabolites of SS rats, a set of combined dietary supplements containing amino acids and organic acids (AO) were designed. The purpose of the present study was to evaluate the effect of AO supplementation on the blood pressure of SS rats after the HS diet and clarify the mechanism of AO by metabolomics and biochemical analyses. The results showed that AO supplementation avoided the elevation of blood pressure induced by the HS diet in SS rats, increased the renal antioxidant enzyme activities (catalase, superoxide dismutase, glutathione reductase, and glutathione S-transferase), reduced the H2O2 and MDA levels, and restored the normal antioxidant status of the serum and kidneys. AO also reversed the decrease in the nitric oxide (NO) levels and NO synthase activity induced by the HS feed, which involved the L-arginine/NO pathway. Metabolomics analysis showed that AO administration increased the levels of amino acids such as cysteine, glycine, hypotaurine, and lysine in the renal medulla and the levels of leucine, isoleucine, and serine in the renal cortex. Of note, lysine, hypotaurine and glycine had higher metabolic centrality in the metabolic correlation network of the renal medulla after AO administration. In conclusion, AO intervention could prevent HS diet-induced hypertension in SS rats by restoring the metabolic homeostasis of the kidneys. Hence, AO has the potential to become a functional food additive to improve salt-sensitive hypertension.
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Affiliation(s)
- Pengfei Yang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Luxin Zhou
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Meng Chen
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Li Zeng
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Yanan Ouyang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xuewei Zheng
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xiangbo Chen
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Zhe Yang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Zhongmin Tian
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
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20
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Odom JD, Sutton VR. Metabolomics in Clinical Practice: Improving Diagnosis and Informing Management. Clin Chem 2021; 67:1606-1617. [PMID: 34633032 DOI: 10.1093/clinchem/hvab184] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 08/17/2021] [Indexed: 11/14/2022]
Abstract
BACKGROUND Metabolomics is the study of small molecules to simultaneously identify multiple low molecular weight molecules in a system. Broadly speaking, metabolomics can be subdivided into targeted and untargeted types of analysis, each type having advantages and drawbacks. Targeted metabolomics can quantify analytes but only looks for known or expected analytes related to particular disease(s), whereas untargeted metabolomics is typically nonquantitative but can detect thousands of analytes from an agnostic or nonhypothesis driven perspective, allowing for novel discoveries. CONTENT One application of metabolomics is the study of inborn errors of metabolism (IEM). The biochemical hallmark of IEMs is decreased concentrations of analytes distal to the enzymatic defect and buildup of analytes proximal to the defect. Metabolomics can detect these changes with one test and is effective in screening for and diagnosis of IEMs. Metabolomics has also been used to study many nonmetabolic diseases such as autism spectrum disorder, various cancers, and multiple congenital anomalies syndromes. Metabolomics has led to the discovery of many novel biomarkers of disease. Recent publications demonstrate how metabolomics can be useful clinically in the diagnosis and management of patients, as well as for research and clinical discovery. SUMMARY Metabolomics has proved to be a useful tool clinically for screening and diagnostic purposes and from a research perspective for the detection of novel biomarkers. In the future, metabolomics will likely become a routine part of the evaluation for many diseases as either a supplementary test or it may simply replace historical analyses that require several individual tests and sample types.
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Affiliation(s)
- John D Odom
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX.,Baylor Genetics Laboratory, Houston, TX
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21
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Dessì A, Bosco A, Pintus R, Picari G, Mazza S, Fanos V. Epigenetics and Modulations of Early Flavor Experiences: Can Metabolomics Contribute to Prevention during Weaning? Nutrients 2021; 13:nu13103351. [PMID: 34684350 PMCID: PMC8539480 DOI: 10.3390/nu13103351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 09/16/2021] [Accepted: 09/20/2021] [Indexed: 11/29/2022] Open
Abstract
The significant increase in chronic non-communicable diseases has changed the global epidemiological landscape. Among these, obesity is the most relevant in the pediatric field. This has pushed the world of research towards a new paradigm: preventive and predictive medicine. Therefore, the window of extreme plasticity that characterizes the first stage of development cannot be underestimated. In this context, nutrition certainly plays a primary role, being one of the most important epigenetic modulators known to date. Weaning, therefore, has a crucial role that must be analyzed far beyond the simple achievement of nutritional needs. Furthermore, the taste experience and the family context are fundamental for future food choices and can no longer be underestimated. The use of metabolomics allows, through the recognition of early disease markers and food-specific metabolites, the planning of an individualized and precise diet. In addition, the possibility of identifying particular groups of subjects at risk and the careful monitoring of adherence to dietary therapy may represent the basis for this change.
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22
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Roointan A, Gheisari Y, Hudkins KL, Gholaminejad A. Non-invasive metabolic biomarkers for early diagnosis of diabetic nephropathy: Meta-analysis of profiling metabolomics studies. Nutr Metab Cardiovasc Dis 2021; 31:2253-2272. [PMID: 34059383 DOI: 10.1016/j.numecd.2021.04.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 04/12/2021] [Accepted: 04/25/2021] [Indexed: 12/15/2022]
Abstract
AIM Diabetic nephropathy (DN) is one of the worst complications of diabetes. Despite a growing number of DN metabolite profiling studies, most studies are suffering from inconsistency in their findings. The main goal of this meta-analysis was to reach to a consensus panel of significantly dysregulated metabolites as potential biomarkers in DN. DATA SYNTHESIS To identify the significant dysregulated metabolites, meta-analysis was performed by "vote-counting rank" and "robust rank aggregation" strategies. Bioinformatics analyses were performed to identify the most affected genes and pathways. Among 44 selected studies consisting of 98 metabolite profiles, 17 metabolites (9 up-regulated and 8 down-regulated metabolites), were identified as significant ones by both the meta-analysis strategies (p-value<0.05 and OR>2 or <0.5) and selected as DN metabolite meta-signature. Furthermore, enrichment analyses confirmed the involvement of various effective biological pathways in DN pathogenesis, such as urea cycle, TCA cycle, glycolysis, and amino acid metabolisms. Finally, by performing a meta-analysis over existing time-course studies in DN, the results indicated that lactic acid, hippuric acid, allantoin (in urine), and glutamine (in blood), are the topmost non-invasive early diagnostic biomarkers. CONCLUSION The identified metabolites are potentially involved in diabetic nephropathy pathogenesis and could be considered as biomarkers or drug targets in the disease. PROSPERO REGISTRATION NUMBER CRD42020197697.
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Affiliation(s)
- Amir Roointan
- Regenerative Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Yousof Gheisari
- Regenerative Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Kelly L Hudkins
- Department of Pathology, University of Washington, School of Medicine, Seattle, United States
| | - Alieh Gholaminejad
- Regenerative Medicine Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
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Li X, Milosavljevic A, Elsea SH, Wang CC, Scaglia F, Syngelaki A, Nicolaides KH, Poon LC. Effective Aspirin Treatment of Women at Risk for Preeclampsia Delays the Metabolic Clock of Gestation. Hypertension 2021; 78:1398-1410. [PMID: 34225470 DOI: 10.1161/hypertensionaha.121.17448] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Preeclampsia, characterized by the onset of hypertension with significant proteinuria after 20 weeks' gestation, is one of the leading causes of maternal and perinatal morbidity and mortality. Prophylactic low-dose aspirin treatment reduces the rate of preterm preeclampsia in high-risk women, but a significant proportion still develops preeclampsia. The mechanism of the prophylactic response is unknown. Here, the untargeted metabolomics analysis of 144 plasma samples from high-risk pregnant women before (11-13 weeks) and after (20-23 weeks) aspirin/placebo treatment elucidated metabolic effects of aspirin and metabolic differences potentially associated with the variation of the treatment response. We demonstrated that aspirin treatment resulted in a strong drug-associated metabolomics signature and that the preeclamptic or nonpreeclamptic outcome in response to treatment was significantly associated with the level of internal aspirin exposure ascertained from metabolomics data (t test, P=0.0083). Comparing women with and without preeclampsia after aspirin treatment, differences in 73 metabolites were detected, some of which involve pathways whose regulation is of importance in pregnancy and placental functions, such as glycerophospholipids metabolism, polyunsaturated fatty acid metabolism, and steroid hormone biosynthesis. To further examine the hypothesis that aspirin delays gestational age advancement and thus the onset of preeclampsia, we constructed a metabolic clock on pretreatment and placebo-treated samples that estimated gestational age with high accuracy and found that aspirin significantly decelerated metabolic gestational age by 1.27 weeks (95% CI, 0.66-1.88 weeks), and partially reversed one-fourth of the metabolites changed over gestational age advancement, suggesting that aspirin treatment slowed down the metabolic clock of gestation.
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Affiliation(s)
- Xiqi Li
- Molecular and Human Genetics Department, Baylor College of Medicine, Houston, TX (X.L., A.M., S.H.E., F.S.)
| | - Aleksandar Milosavljevic
- Molecular and Human Genetics Department, Baylor College of Medicine, Houston, TX (X.L., A.M., S.H.E., F.S.)
| | - Sarah H Elsea
- Molecular and Human Genetics Department, Baylor College of Medicine, Houston, TX (X.L., A.M., S.H.E., F.S.)
| | - Chi Chiu Wang
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong. (C.C.W., L.C.P.).,Li Ka Shing Institute of Health Sciences, School of Biomedical Sciences, Chinese University of Hong Kong-Sichuan University Joint Laboratory in Reproductive Medicine, The Chinese University of Hong Kong. (C.C.W., K.H.N.)
| | - Fernando Scaglia
- Molecular and Human Genetics Department, Baylor College of Medicine, Houston, TX (X.L., A.M., S.H.E., F.S.).,Texas Children's Hospital, Houston (F.S.).,Joint BCM-CUHK Center of Medical Genetics, Prince of Wales Hospital, Shatin, Hong Kong (F.S.)
| | - Argyro Syngelaki
- Fetal Medicine Research Institute, Harris Birthright Centre, King's College Hospital, London, United Kingdom (A.S.)
| | - Kypros H Nicolaides
- Li Ka Shing Institute of Health Sciences, School of Biomedical Sciences, Chinese University of Hong Kong-Sichuan University Joint Laboratory in Reproductive Medicine, The Chinese University of Hong Kong. (C.C.W., K.H.N.)
| | - Liona C Poon
- Department of Obstetrics and Gynaecology, The Chinese University of Hong Kong. (C.C.W., L.C.P.)
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24
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Liu N, Xiao J, Gijavanekar C, Pappan KL, Glinton KE, Shayota BJ, Kennedy AD, Sun Q, Sutton VR, Elsea SH. Comparison of Untargeted Metabolomic Profiling vs Traditional Metabolic Screening to Identify Inborn Errors of Metabolism. JAMA Netw Open 2021; 4:e2114155. [PMID: 34251446 PMCID: PMC8276086 DOI: 10.1001/jamanetworkopen.2021.14155] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
IMPORTANCE Recent advances in newborn screening (NBS) have improved the diagnosis of inborn errors of metabolism (IEMs); however, many potentially treatable IEMs are not included on NBS panels, nor are they covered in standard, first-line biochemical testing. OBJECTIVE To examine the utility of untargeted metabolomics as a primary screening tool for IEMs by comparing the diagnostic rate of clinical metabolomics with the recommended traditional metabolic screening approach. DESIGN, SETTING, AND PARTICIPANTS This cross-sectional study compares data from 4464 clinical samples received from 1483 unrelated families referred for trio testing of plasma amino acids, plasma acylcarnitine profiling, and urine organic acids (June 2014 to October 2018) and 2000 consecutive plasma samples from 1807 unrelated families (July 2014 to February 2019) received for clinical metabolomic screening at a College of American Pathologists and Clinical Laboratory Improvement Amendments-certified biochemical genetics laboratory. Data analysis was performed from September 2019 to August 2020. EXPOSURES Metabolic and molecular tests performed at a genetic testing reference laboratory in the US and available clinical information for each patient were assessed to determine diagnostic rate. MAIN OUTCOMES AND MEASURES The diagnostic rate of traditional metabolic screening compared with clinical metabolomic profiling was assessed in the context of expanded NBS. RESULTS Of 1483 cases screened by the traditional approach, 912 patients (61.5%) were male and 1465 (98.8%) were pediatric (mean [SD] age, 4.1 [6.0] years; range, 0-65 years). A total of 19 families were identified with IEMs, resulting in a 1.3% diagnostic rate. A total of 14 IEMs were detected, including 3 conditions not included in the Recommended Uniform Screening Panel for NBS. Of the 1807 unrelated families undergoing plasma metabolomic profiling, 1059 patients (58.6%) were male, and 1665 (92.1%) were pediatric (mean [SD] age, 8.1 [10.4] years; range, 0-80 years). Screening identified 128 unique cases with IEMs, giving an overall diagnostic rate of 7.1%. In total, 70 different metabolic conditions were identified, including 49 conditions not presently included on the Recommended Uniform Screening Panel for NBS. CONCLUSIONS AND RELEVANCE These findings suggest that untargeted metabolomics provided a 6-fold higher diagnostic yield compared with the conventional screening approach and identified a broader spectrum of IEMs. Notably, with the expansion of NBS programs, traditional metabolic testing approaches identify few disorders beyond those covered on the NBS. These data support the capability of clinical untargeted metabolomics in screening for IEMs and suggest that broader screening approaches should be considered in the initial evaluation for metabolic disorders.
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Affiliation(s)
- Ning Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
- Baylor Genetics, Houston, Texas
| | - Jing Xiao
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | | | - Kirk L Pappan
- Metabolon, Inc, Durham, North Carolina
- Now with Owlstone Medical, Inc, Research Triangle Park, North Carolina
| | - Kevin E Glinton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
| | - Brian J Shayota
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
- Now with Division of Medical Genetics, Department of Pediatrics, University of Utah, Salt Lake City
| | | | - Qin Sun
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
- Baylor Genetics, Houston, Texas
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
- Baylor Genetics, Houston, Texas
| | - Sarah H Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
- Baylor Genetics, Houston, Texas
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25
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Ford L, Kennedy AD, Goodman KD, Pappan KL, Evans AM, Miller LAD, Wulff JE, Wiggs BR, Lennon JJ, Elsea S, Toal DR. Precision of a Clinical Metabolomics Profiling Platform for Use in the Identification of Inborn Errors of Metabolism. J Appl Lab Med 2021; 5:342-356. [PMID: 32445384 DOI: 10.1093/jalm/jfz026] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 09/09/2019] [Indexed: 01/29/2023]
Abstract
BACKGROUND The application of whole-exome sequencing for the diagnosis of genetic disease has paved the way for systems-based approaches in the clinical laboratory. Here, we describe a clinical metabolomics method for the screening of metabolic diseases through the analysis of a multi-pronged mass spectrometry platform. By simultaneously measuring hundreds of metabolites in a single sample, clinical metabolomics offers a comprehensive approach to identify metabolic perturbations across multiple biochemical pathways. METHODS We conducted a single- and multi-day precision study on hundreds of metabolites in human plasma on 4, multi-arm, high-throughput metabolomics platforms. RESULTS The average laboratory coefficient of variation (CV) on the 4 platforms was between 9.3 and 11.5% (median, 6.5-8.4%), average inter-assay CV on the 4 platforms ranged from 9.9 to 12.6% (median, 7.0-8.3%) and average intra-assay CV on the 4 platforms ranged from 5.7 to 6.9% (median, 3.5-4.4%). In relation to patient sample testing, the precision of multiple biomarkers associated with IEM disorders showed CVs that ranged from 0.2 to 11.0% across 4 analytical batches. CONCLUSIONS This evaluation describes single and multi-day precision across 4 identical metabolomics platforms, comprised each of 4 independent method arms, and reproducibility of the method for the measurement of key IEM metabolites in patient samples across multiple analytical batches, providing evidence that the method is robust and reproducible for the screening of patients with inborn errors of metabolism.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Sarah Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX
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26
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Multiblock metabolomics: An approach to elucidate whole-body metabolism with multiblock principal component analysis. Comput Struct Biotechnol J 2021; 19:1956-1965. [PMID: 33995897 PMCID: PMC8086023 DOI: 10.1016/j.csbj.2021.04.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 03/20/2021] [Accepted: 04/04/2021] [Indexed: 12/16/2022] Open
Abstract
“Multiblock metabolomics” elucidates the global metabolic network in a whole body. “Multiblock metabolomics” combines LC/MS-based metabolomics with multiblock PCA. “Multiblock metabolomics” highlights and elicits organ-specific metabolism. TGs with less unsaturated fatty acids were highly accumulated in the diabetic liver.
Principal component analysis (PCA) is a useful tool for omics analysis to identify underlying factors and visualize relationships between biomarkers. However, this approach is limited in addressing life complexity and further improvement is required. This study aimed to develop a new approach that combines mass spectrometry-based metabolomics with multiblock PCA to elucidate the whole-body global metabolic network, thereby generating comparable metabolite maps to clarify the metabolic relationships among several organs. To evaluate the newly developed method, Zucker diabetic fatty (ZDF) rats (n = 6) were used as type 2 diabetic models and Sprague Dawley (SD) rats (n = 6) as controls. Metabolites in the heart, kidney, and liver were analyzed by capillary electrophoresis and liquid chromatography mass spectrometry, respectively, and the detected metabolites were analyzed by multiblock PCA. More than 300 metabolites were detected in the heart, kidney, and liver. When the metabolites obtained from the three organs were analyzed with multiblock PCA, the score and loading maps obtained were highly synchronized and their metabolism patterns were visually comparable. A significant finding in this study was the different expression patterns in lipid metabolism among the three organs; notably triacylglycerols with polyunsaturated fatty acids or less unsaturated fatty acids showed specific accumulation patterns depending on the organs.
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Key Words
- AMP, adenosine monophosphate
- Biomarkers
- CE/MS, capillary electrophoresis mass spectrometry
- CV, coefficient of variation
- ESI, electrospray ionization
- FABP, fatty acid-binding protein
- GC/MS, gas chromatography mass spectrometry
- LC/MS, liquid chromatography mass spectrometry
- Mass spectrometry
- Metabolomics
- Multiblock PCA
- PCA, principal component analysis
- PPAR, peroxisome proliferator-activated receptor
- QC, quality control
- SD, Sprague Dawley
- TCA, tricarboxylic acid. CoA, coenzyme A
- TG, triacylglycerol
- Type 2 Diabetes
- UPLC, ultra-performance liquid chromatography
- ZDF, Zucker diabetic fatty
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Dobrowolski SF, Phua YL, Sudano C, Spridik K, Zinn PO, Wang Y, Bharathi S, Vockley J, Goetzman E. Phenylalanine hydroxylase deficient phenylketonuria comparative metabolomics identifies energy pathway disruption and oxidative stress. Mol Genet Metab 2021:S1096-7192(21)00686-7. [PMID: 33846068 DOI: 10.1016/j.ymgme.2021.04.002] [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: 03/04/2021] [Revised: 04/02/2021] [Accepted: 04/02/2021] [Indexed: 11/15/2022]
Abstract
Classical phenylketonuria (PKU, OMIM 261600) owes to hepatic deficiency of phenylalanine hydroxylase (PAH) that enzymatically converts phenylalanine (Phe) to tyrosine (Tyr). PKU neurologic phenotypes include impaired brain development, decreased myelination, early onset mental retardation, seizures, and late-onset features (neuropsychiatric, Parkinsonism). PAH deficiency leads to systemic hyperphenylalaninemia; however, the impact of Phe varies between tissues. To characterize tissue response to hyperphenylalaninemia, metabolomics was applied to tissue from therapy noncompliant classical PKU patients (blood, liver), the Pahenu2 classical PKU mouse (blood, liver, brain) and the PAH deficient pig (blood, liver, brain, cerebrospinal fluid). In blood, liver, and CSF from both patients and animal models over-represented analytes were principally Phe, Phe catabolites, and Phe-related analytes (conjugates, Phe-containing dipeptides). In addition to Phe and Phe-related analytes, the metabolomic profile of PKU brain tissue (mouse, pig) evidenced oxidative stress responses and energy dysregulation. In Pahenu2 and PKU pig brain tissues, anti-oxidative response by glutathione and homocarnosine is apparent. Oxidative stress in Pahenu2 brain was further demonstrated by increased reactive oxygen species. In Pahenu2 and PKU pig brain, an increased NADH/NAD ratio suggests a respiratory chain dysfunction. Respirometry in PKU brain mitochondria (mouse, pig) functionally confirmed reduced respiratory chain activity. Glycolysis pathway analytes are over-represented in PKU brain tissue (mouse, pig). PKU pathologies owe to liver metabolic deficiency; yet, PKU liver tissue (mouse, pig, human) shows neither energy disruption nor anti-oxidative response. Unique aspects of metabolomic homeostasis in PKU brain tissue along with increased reactive oxygen species and respiratory chain deficit provide insight to neurologic disease mechanisms. While some elements of assumed, long standing PKU neuropathology are enforced by metabolomic data (e.g. reduced tryptophan and serotonin representation), energy dysregulation and tissue oxidative stress expand mechanisms underlying neuropathology.
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Affiliation(s)
- Steven F Dobrowolski
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States.
| | - Yu Leng Phua
- Division of Medical Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States
| | - Cayla Sudano
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States
| | - Kayla Spridik
- Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States
| | - Pascal O Zinn
- Department of Neurological Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States
| | - Yudong Wang
- Division of Medical Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States
| | - Sivakama Bharathi
- Division of Medical Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States
| | - Jerry Vockley
- Division of Medical Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States
| | - Eric Goetzman
- Division of Medical Genetics, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15224, United States
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28
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Thistlethwaite LR, Petrosyan V, Li X, Miller MJ, Elsea SH, Milosavljevic A. CTD: An information-theoretic algorithm to interpret sets of metabolomic and transcriptomic perturbations in the context of graphical models. PLoS Comput Biol 2021; 17:e1008550. [PMID: 33513132 PMCID: PMC7875364 DOI: 10.1371/journal.pcbi.1008550] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 02/10/2021] [Accepted: 11/16/2020] [Indexed: 01/17/2023] Open
Abstract
We consider the following general family of algorithmic problems that arises in transcriptomics, metabolomics and other fields: given a weighted graph G and a subset of its nodes S, find subsets of S that show significant connectedness within G. A specific solution to this problem may be defined by devising a scoring function, the Maximum Clique problem being a classic example, where S includes all nodes in G and where the score is defined by the size of the largest subset of S fully connected within G. Major practical obstacles for the plethora of algorithms addressing this type of problem include computational efficiency and, particularly for more complex scores which take edge weights into account, the computational cost of permutation testing, a statistical procedure required to obtain a bound on the p-value for a connectedness score. To address these problems, we developed CTD, "Connect the Dots", a fast algorithm based on data compression that detects highly connected subsets within S. CTD provides information-theoretic upper bounds on p-values when S contains a small fraction of nodes in G without requiring computationally costly permutation testing. We apply the CTD algorithm to interpret multi-metabolite perturbations due to inborn errors of metabolism and multi-transcript perturbations associated with breast cancer in the context of disease-specific Gaussian Markov Random Field networks learned directly from respective molecular profiling data.
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Affiliation(s)
- Lillian R. Thistlethwaite
- Quantitative and Computational Biosciences Program, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Varduhi Petrosyan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Xiqi Li
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Marcus J. Miller
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Sarah H. Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Aleksandar Milosavljevic
- Quantitative and Computational Biosciences Program, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
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29
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Messa GM, Napolitano F, Elsea SH, di Bernardo D, Gao X. A Siamese neural network model for the prioritization of metabolic disorders by integrating real and simulated data. Bioinformatics 2020; 36:i787-i794. [PMID: 33381827 DOI: 10.1093/bioinformatics/btaa841] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
MOTIVATION Untargeted metabolomic approaches hold a great promise as a diagnostic tool for inborn errors of metabolisms (IEMs) in the near future. However, the complexity of the involved data makes its application difficult and time consuming. Computational approaches, such as metabolic network simulations and machine learning, could significantly help to exploit metabolomic data to aid the diagnostic process. While the former suffers from limited predictive accuracy, the latter is normally able to generalize only to IEMs for which sufficient data are available. Here, we propose a hybrid approach that exploits the best of both worlds by building a mapping between simulated and real metabolic data through a novel method based on Siamese neural networks (SNN). RESULTS The proposed SNN model is able to perform disease prioritization for the metabolic profiles of IEM patients even for diseases that it was not trained to identify. To the best of our knowledge, this has not been attempted before. The developed model is able to significantly outperform a baseline model that relies on metabolic simulations only. The prioritization performances demonstrate the feasibility of the method, suggesting that the integration of metabolic models and data could significantly aid the IEM diagnosis process in the near future. AVAILABILITY AND IMPLEMENTATION Metabolic datasets used in this study are publicly available from the cited sources. The original data produced in this study, including the trained models and the simulated metabolic profiles, are also publicly available (Messa et al., 2020).
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Affiliation(s)
- Gian Marco Messa
- Computational Bioscience Research Center (CBRC), Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Francesco Napolitano
- Computational Bioscience Research Center (CBRC), Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Sarah H Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Diego di Bernardo
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli 80078, Italy.,Department of Chemical, Materials and Industrial Production Engineering, University of Naples Federico II, 80125 Naples, Italy
| | - Xin Gao
- Computational Bioscience Research Center (CBRC), Computer, Electrical and Mathematical Sciences and Engineering (CEMSE) Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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30
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Evans AM, O'Donovan C, Playdon M, Beecher C, Beger RD, Bowden JA, Broadhurst D, Clish CB, Dasari S, Dunn WB, Griffin JL, Hartung T, Hsu PC, Huan T, Jans J, Jones CM, Kachman M, Kleensang A, Lewis MR, Monge ME, Mosley JD, Taylor E, Tayyari F, Theodoridis G, Torta F, Ubhi BK, Vuckovic D. Dissemination and analysis of the quality assurance (QA) and quality control (QC) practices of LC-MS based untargeted metabolomics practitioners. Metabolomics 2020; 16:113. [PMID: 33044703 PMCID: PMC7641040 DOI: 10.1007/s11306-020-01728-5] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 09/20/2020] [Indexed: 02/07/2023]
Abstract
INTRODUCTION The metabolomics quality assurance and quality control consortium (mQACC) evolved from the recognized need for a community-wide consensus on improving and systematizing quality assurance (QA) and quality control (QC) practices for untargeted metabolomics. OBJECTIVES In this work, we sought to identify and share the common and divergent QA and QC practices amongst mQACC members and collaborators who use liquid chromatography-mass spectrometry (LC-MS) in untargeted metabolomics. METHODS All authors voluntarily participated in this collaborative research project by providing the details of and insights into the QA and QC practices used in their laboratories. This sharing was enabled via a six-page questionnaire composed of over 120 questions and comment fields which was developed as part of this work and has proved the basis for ongoing mQACC outreach. RESULTS For QA, many laboratories reported documenting maintenance, calibration and tuning (82%); having established data storage and archival processes (71%); depositing data in public repositories (55%); having standard operating procedures (SOPs) in place for all laboratory processes (68%) and training staff on laboratory processes (55%). For QC, universal practices included using system suitability procedures (100%) and using a robust system of identification (Metabolomics Standards Initiative level 1 identification standards) for at least some of the detected compounds. Most laboratories used QC samples (>86%); used internal standards (91%); used a designated analytical acquisition template with randomized experimental samples (91%); and manually reviewed peak integration following data acquisition (86%). A minority of laboratories included technical replicates of experimental samples in their workflows (36%). CONCLUSIONS Although the 23 contributors were researchers with diverse and international backgrounds from academia, industry and government, they are not necessarily representative of the worldwide pool of practitioners due to the recruitment method for participants and its voluntary nature. However, both questionnaire and the findings presented here have already informed and led other data gathering efforts by mQACC at conferences and other outreach activities and will continue to evolve in order to guide discussions for recommendations of best practices within the community and to establish internationally agreed upon reporting standards. We very much welcome further feedback from readers of this article.
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Affiliation(s)
| | - Claire O'Donovan
- European Molecular Biology Laboratory (EMBL), The European Bioinformatics Institute, Cambridgeshire, UK
| | | | | | - Richard D Beger
- National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR, USA
| | - John A Bowden
- College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - David Broadhurst
- Centre for Integrative Metabolomics & Computational Biology, School of Science, Edith Cowan University, Joondalup, WA, Australia
| | | | - Surendra Dasari
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN, USA
| | - Warwick B Dunn
- School of Biosciences, Phenome Centre Birmingham and Institute of Metabolism and Systems Research, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | - Julian L Griffin
- Department of Biochemistry, University of Cambridge, Cambridge, UK
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK
| | - Thomas Hartung
- Center for Alternatives To Animal Testing (CAAT), Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Ping- Ching Hsu
- University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Tao Huan
- Department of Chemistry, University of British Columbia, Vancouver, Canada
| | - Judith Jans
- University Medical Center Utrecht, Utrecht, Netherlands
| | - Christina M Jones
- Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | | | - Andre Kleensang
- Center for Alternatives To Animal Testing (CAAT), Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD, USA
| | - Matthew R Lewis
- National Phenome Centre, Imperial College London, London, UK
| | - María Eugenia Monge
- Centro de Investigaciones en Bionanociencias (CIBION), Consejo Nacional de Investigaciones Científicas Y Técnicas (CONICET), C1425FQD, Ciudad de Buenos Aires, Argentina
| | - Jonathan D Mosley
- Center for Environmental Measurement and Modeling, Environmental Protection Agency, Washington, DC, USA
| | | | - Fariba Tayyari
- Department of Internal Medicine, Metabolomics Core, The University of Iowa, Iowa City, Iowa, USA
| | | | - Federico Torta
- Singapore Lipidomics Incubator, Department of Biochemistry, Life Sciences Institute and Yong Loo Lin School of Medicine, National University of Singapore, Kent Ridge, Singapore
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Shayota BJ, Donti TR, Xiao J, Gijavanekar C, Kennedy AD, Hubert L, Rodan L, Vanderpluym C, Nowak C, Bjornsson HT, Ganetzky R, Berry GT, Pappan KL, Sutton VR, Sun Q, Elsea SH. Untargeted metabolomics as an unbiased approach to the diagnosis of inborn errors of metabolism of the non-oxidative branch of the pentose phosphate pathway. Mol Genet Metab 2020; 131:147-154. [PMID: 32828637 PMCID: PMC8630378 DOI: 10.1016/j.ymgme.2020.07.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/31/2020] [Accepted: 07/31/2020] [Indexed: 12/27/2022]
Abstract
Inborn errors of metabolism (IEM) involving the non-oxidative pentose phosphate pathway (PPP) include the two relatively rare conditions, transketolase deficiency and transaldolase deficiency, both of which can be difficult to diagnosis given their non-specific clinical presentations. Current biochemical testing approaches require an index of suspicion to consider targeted urine polyol testing. To determine whether a broad-spectrum biochemical test could accurately identify a specific metabolic pattern defining IEMs of the non-oxidative PPP, we employed the use of clinical metabolomic profiling as an unbiased novel approach to diagnosis. Subjects with molecularly confirmed IEMs of the PPP were included in this study. Targeted quantitative analysis of polyols in urine and plasma samples was accomplished with chromatography and mass spectrometry. Semi-quantitative unbiased metabolomic analysis of urine and plasma samples was achieved by assessing small molecules via liquid chromatography and high-resolution mass spectrometry. Results from untargeted and targeted analyses were then compared and analyzed for diagnostic acuity. Two siblings with transketolase (TKT) deficiency and three unrelated individuals with transaldolase (TALDO) deficiency were identified for inclusion in the study. For both IEMs, targeted polyol testing and untargeted metabolomic testing on urine and/or plasma samples identified typical perturbations of the respective disorder. Additionally, untargeted metabolomic testing revealed elevations in other PPP metabolites not typically measured with targeted polyol testing, including ribonate, ribose, and erythronate for TKT deficiency and ribonate, erythronate, and sedoheptulose 7-phosphate in TALDO deficiency. Non-PPP alternations were also noted involving tryptophan, purine, and pyrimidine metabolism for both TKT and TALDO deficient patients. Targeted polyol testing and untargeted metabolomic testing methods were both able to identify specific biochemical patterns indicative of TKT and TALDO deficiency in both plasma and urine samples. In addition, untargeted metabolomics was able to identify novel biomarkers, thereby expanding the current knowledge of both conditions and providing further insight into potential underlying pathophysiological mechanisms. Furthermore, untargeted metabolomic testing offers the advantage of having a single effective biochemical screening test for identification of rare IEMs, like TKT and TALDO deficiencies, that may otherwise go undiagnosed due to their generally non-specific clinical presentations.
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MESH Headings
- Adult
- Biomarkers/blood
- Carbohydrate Metabolism, Inborn Errors/blood
- Carbohydrate Metabolism, Inborn Errors/genetics
- Carbohydrate Metabolism, Inborn Errors/metabolism
- Carbohydrate Metabolism, Inborn Errors/pathology
- Child
- Child, Preschool
- Chromatography, Liquid
- Female
- Humans
- Infant
- Male
- Mass Spectrometry
- Metabolism, Inborn Errors/blood
- Metabolism, Inborn Errors/genetics
- Metabolism, Inborn Errors/metabolism
- Metabolism, Inborn Errors/pathology
- Metabolomics
- Pentose Phosphate Pathway/genetics
- Transaldolase/blood
- Transaldolase/deficiency
- Transaldolase/genetics
- Transaldolase/metabolism
- Transketolase/blood
- Transketolase/deficiency
- Transketolase/genetics
- Young Adult
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Affiliation(s)
- Brian J Shayota
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Taraka R Donti
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Jing Xiao
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Baylor Genetics, Houston, TX, USA
| | | | | | - Leroy Hubert
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Lance Rodan
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | | | - Catherine Nowak
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | - Hans T Bjornsson
- McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Faculty of Medicine, University of Iceland, Reykjavik, Iceland; Landspitali University Hospital, Reykjavik, Iceland
| | - Rebecca Ganetzky
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Gerard T Berry
- Division of Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA
| | | | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Baylor Genetics, Houston, TX, USA
| | - Qin Sun
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Baylor Genetics, Houston, TX, USA
| | - Sarah H Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA; Baylor Genetics, Houston, TX, USA.
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Hu L, Liu J, Zhang W, Wang T, Zhang N, Lee YH, Lu H. FUNCTIONAL METABOLOMICS DECIPHER BIOCHEMICAL FUNCTIONS AND ASSOCIATED MECHANISMS UNDERLIE SMALL-MOLECULE METABOLISM. MASS SPECTROMETRY REVIEWS 2020; 39:417-433. [PMID: 31682024 DOI: 10.1002/mas.21611] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 10/08/2019] [Accepted: 10/10/2019] [Indexed: 06/10/2023]
Abstract
Metabolism is the collection of biochemical reactions enabled by chemically diverse metabolites, which facilitate different physiological processes to exchange substances and synthesize energy in diverse living organisms. Metabolomics has emerged as a cutting-edge method to qualify and quantify the metabolites in different biological matrixes, and it has the extraordinary capacity to interrogate the biological significance that underlies metabolic modification and modulation. Liquid chromatography combined with mass spectrometry (LC/MS), as a robust platform for metabolomics analysis, has increased in popularity over the past 10 years due to its excellent sensitivity, throughput, and versatility. However, metabolomics investigation currently provides us with only phenotype data without revealing the biochemical functions and associated mechanisms. This limitation indeed weakens the core value of metabolomics data in a broad spectrum of the life sciences. In recent years, the scientific community has actively explored the functional features of metabolomics and translated this cutting-edge approach to be used to solve key multifaceted questions, such as disease pathogenesis, the therapeutic discovery of drugs, nutritional issues, agricultural problems, environmental toxicology, and microbial evolution. Here, we are the first to briefly review the history and applicable progression of LC/MS-based metabolomics, with an emphasis on the applications of metabolic phenotyping. Furthermore, we specifically highlight the next era of LC/MS-based metabolomics to target functional metabolomes, through which we can answer phenotype-related questions to elucidate biochemical functions and associated mechanisms implicated in dysregulated metabolism. Finally, we propose many strategies to enhance the research capacity of functional metabolomics by enabling the combination of contemporary omics technologies and cutting-edge biochemical techniques. The main purpose of this review is to improve the understanding of LC/MS-based metabolomics, extending beyond the conventional metabolic phenotype toward biochemical functions and associated mechanisms, to enhance research capability and to enlarge the applicable scope of functional metabolomics in small-molecule metabolism in different living organisms.
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Affiliation(s)
- Longlong Hu
- Laboratory for Functional Metabolomics Science, Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jingjing Liu
- Laboratory for Functional Metabolomics Science, Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Wenhua Zhang
- Laboratory for Functional Metabolomics Science, Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, 200240, China
- Department of Pharmacognosy, College of Pharmacy, Heilongjiang University of Chinese Medicine, Harbin, 150040, China
| | - Tianyu Wang
- Laboratory for Functional Metabolomics Science, Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Ning Zhang
- Department of Pharmacognosy, College of Pharmacy, Heilongjiang University of Chinese Medicine, Harbin, 150040, China
- Department of Pharmaceutical Analysis, College of Jiamusi, Heilongjiang University of Chinese Medicine, Harbin, 121000, China
| | - Yie Hou Lee
- Translational 'Omics and Biomarkers Group, KK Research Centre, KK Women's and Children's Hospital, Singapore, 229899, Singapore
- OBGYN-Academic Clinical Program, Duke-NUS Medical School, Singapore, 169857, Singapore
| | - Haitao Lu
- Laboratory for Functional Metabolomics Science, Key Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, 200240, China
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Almontashiri NAM, Zha L, Young K, Law T, Kellogg MD, Bodamer OA, Peake RWA. Clinical Validation of Targeted and Untargeted Metabolomics Testing for Genetic Disorders: A 3 Year Comparative Study. Sci Rep 2020; 10:9382. [PMID: 32523032 PMCID: PMC7287104 DOI: 10.1038/s41598-020-66401-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 05/19/2020] [Indexed: 02/04/2023] Open
Abstract
Global untargeted metabolomics (GUM) has entered clinical diagnostics for genetic disorders. We compared the clinical utility of GUM with traditional targeted metabolomics (TM) as a screening tool in patients with established genetic disorders and determined the scope of GUM as a discovery tool in patients with no diagnosis under investigation. We compared TM and GUM data in 226 patients. The first cohort (n = 87) included patients with confirmed inborn errors of metabolism (IEM) and genetic syndromes; the second cohort (n = 139) included patients without diagnosis who were undergoing evaluation for a genetic disorder. In patients with known disorders (n = 87), GUM performed with a sensitivity of 86% (95% CI: 78–91) compared with TM for the detection of 51 diagnostic metabolites. The diagnostic yield of GUM in patients under evaluation with no established diagnosis (n = 139) was 0.7%. GUM successfully detected the majority of diagnostic compounds associated with known IEMs. The diagnostic yield of both targeted and untargeted metabolomics studies is low when assessing patients with non-specific, neurological phenotypes. GUM shows promise as a validation tool for variants of unknown significance in candidate genes in patients with non-specific phenotypes.
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Affiliation(s)
- Naif A M Almontashiri
- Department of Laboratory Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Faculty of Applied Medical Sciences and the Center for Genetics and Inherited Disorders, Taibah University, Almadinah Almunwarah, Saudi Arabia
| | - Li Zha
- Department of Laboratory Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Kim Young
- Department of Laboratory Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Terence Law
- Department of Laboratory Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Mark D Kellogg
- Department of Laboratory Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Olaf A Bodamer
- Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.,Broad Institute of Harvard University and MIT, Cambridge, Massachusetts, USA
| | - Roy W A Peake
- Department of Laboratory Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
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Alaimo JT, Glinton KE, Liu N, Xiao J, Yang Y, Reid Sutton V, Elsea SH. Integrated analysis of metabolomic profiling and exome data supplements sequence variant interpretation, classification, and diagnosis. Genet Med 2020; 22:1560-1566. [PMID: 32439973 PMCID: PMC7483344 DOI: 10.1038/s41436-020-0827-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/26/2020] [Accepted: 04/27/2020] [Indexed: 12/17/2022] Open
Abstract
PURPOSE A primary barrier to improving exome sequencing diagnostic rates is the interpretation of variants of uncertain clinical significance. We aimed to determine the contribution of integrated untargeted metabolomics in the analysis of exome sequencing data by retrospective analysis of patients evaluated by both exome sequencing and untargeted metabolomics within the same clinical laboratory. METHODS Exome sequencing and untargeted metabolomic data were collected and analyzed for 170 patients. Pathogenic variants, likely pathogenic variants, and variants of uncertain significance in genes associated with a biochemical phenotype were extracted. Metabolomic data were evaluated to determine if these variants resulted in biochemical abnormalities that could be used to support their interpretation using current American College of Genetics and Genomics (ACMG) guidelines. RESULTS Metabolomic data contributed to the interpretation of variants in 74 individuals (43.5%) over 73 different genes. The data allowed for the reclassification of 9 variants as likely benign, 15 variants as likely pathogenic, and 3 variants as pathogenic. Metabolomic data confirmed a clinical diagnosis in 21 cases, for a diagnostic rate of 12.3% in this population. CONCLUSION Untargeted metabolomics can serve as a useful adjunct to exome sequencing by providing valuable functional data that may not otherwise be clinically available, resulting in improved variant classification.
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Affiliation(s)
- Joseph T Alaimo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Baylor Genetics, Houston, TX, USA.,Department of Pediatrics, University of Missouri-Kansas City School of Medicine, Kansas City, MO, USA
| | - Kevin E Glinton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Ning Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Baylor Genetics, Houston, TX, USA
| | - Jing Xiao
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Baylor Genetics, Houston, TX, USA
| | - Yaping Yang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.,Baylor Genetics, Houston, TX, USA
| | - Sarah H Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA. .,Baylor Genetics, Houston, TX, USA.
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35
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Mordaunt D, Cox D, Fuller M. Metabolomics to Improve the Diagnostic Efficiency of Inborn Errors of Metabolism. Int J Mol Sci 2020; 21:ijms21041195. [PMID: 32054038 PMCID: PMC7072749 DOI: 10.3390/ijms21041195] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 02/08/2020] [Accepted: 02/09/2020] [Indexed: 12/21/2022] Open
Abstract
Early diagnosis of inborn errors of metabolism (IEM)—a large group of congenital disorders—is critical, given that many respond well to targeted therapy. Newborn screening programs successfully capture a proportion of patients enabling early recognition and prompt initiation of therapy. For others, the heterogeneity in clinical presentation often confuses diagnosis with more common conditions. In the absence of family history and following clinical suspicion, the laboratory diagnosis typically begins with broad screening tests to circumscribe specialised metabolite and/or enzyme assays to identify the specific IEM. Confirmation of the biochemical diagnosis is usually achieved by identifying pathogenic genetic variants that will also enable cascade testing for family members. Unsurprisingly, this diagnostic trajectory is too often a protracted and lengthy process resulting in delays in diagnosis and, importantly, therapeutic intervention for these rare conditions is also postponed. Implementation of mass spectrometry technologies coupled with the expanding field of metabolomics is changing the landscape of diagnosing IEM as numerous metabolites, as well as enzymes, can now be measured collectively on a single mass spectrometry-based platform. As the biochemical consequences of impaired metabolism continue to be elucidated, the measurement of secondary metabolites common across groups of IEM will facilitate algorithms to further increase the efficiency of diagnosis.
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Affiliation(s)
- Dylan Mordaunt
- Genetics and Molecular Pathology, SA Pathology at Women’s and Children’s Hospital, 72 King William Road, North Adelaide, SA 5006, Australia; (D.M.); (D.C.)
- School of Medicine, University of Adelaide, Adelaide, SA 5000, Australia
| | - David Cox
- Genetics and Molecular Pathology, SA Pathology at Women’s and Children’s Hospital, 72 King William Road, North Adelaide, SA 5006, Australia; (D.M.); (D.C.)
| | - Maria Fuller
- Genetics and Molecular Pathology, SA Pathology at Women’s and Children’s Hospital, 72 King William Road, North Adelaide, SA 5006, Australia; (D.M.); (D.C.)
- School of Medicine, University of Adelaide, Adelaide, SA 5000, Australia
- Correspondence: ; Tel.: +61-8-8161-6741
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36
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Haijes HA, van der Ham M, Prinsen HC, Broeks MH, van Hasselt PM, de Sain-van der Velden MG, Verhoeven-Duif NM, Jans JJ. Untargeted Metabolomics for Metabolic Diagnostic Screening with Automated Data Interpretation Using a Knowledge-Based Algorithm. Int J Mol Sci 2020; 21:ijms21030979. [PMID: 32024143 PMCID: PMC7037085 DOI: 10.3390/ijms21030979] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 01/26/2020] [Accepted: 01/29/2020] [Indexed: 11/16/2022] Open
Abstract
Untargeted metabolomics may become a standard approach to address diagnostic requests, but, at present, data interpretation is very labor-intensive. To facilitate its implementation in metabolic diagnostic screening, we developed a method for automated data interpretation that preselects the most likely inborn errors of metabolism (IEM). The input parameters of the knowledge-based algorithm were (1) weight scores assigned to 268 unique metabolites for 119 different IEM based on literature and expert opinion, and (2) metabolite Z-scores and ranks based on direct-infusion high resolution mass spectrometry. The output was a ranked list of differential diagnoses (DD) per sample. The algorithm was first optimized using a training set of 110 dried blood spots (DBS) comprising 23 different IEM and 86 plasma samples comprising 21 different IEM. Further optimization was performed using a set of 96 DBS consisting of 53 different IEM. The diagnostic value was validated in a set of 115 plasma samples, which included 58 different IEM and resulted in the correct diagnosis being included in the DD of 72% of the samples, comprising 44 different IEM. The median length of the DD was 10 IEM, and the correct diagnosis ranked first in 37% of the samples. Here, we demonstrate the accuracy of the diagnostic algorithm in preselecting the most likely IEM, based on the untargeted metabolomics of a single sample. We show, as a proof of principle, that automated data interpretation has the potential to facilitate the implementation of untargeted metabolomics for metabolic diagnostic screening, and we provide suggestions for further optimization of the algorithm to improve diagnostic accuracy.
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Affiliation(s)
- Hanneke A. Haijes
- Section Metabolic Diagnostics, Department of Genetics, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, The Netherlands
- Section Metabolic Diagnostics, Department of Child Health, Wilhelmina Children’s Hospital, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, The Netherlands
- Correspondence: (H.A.H.); (J.J.M.J.)
| | - Maria van der Ham
- Section Metabolic Diagnostics, Department of Genetics, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, The Netherlands
| | - Hubertus C.M.T. Prinsen
- Section Metabolic Diagnostics, Department of Genetics, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, The Netherlands
| | - Melissa H. Broeks
- Section Metabolic Diagnostics, Department of Genetics, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, The Netherlands
| | - Peter M. van Hasselt
- Section Metabolic Diagnostics, Department of Child Health, Wilhelmina Children’s Hospital, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, The Netherlands
| | - Monique G.M. de Sain-van der Velden
- Section Metabolic Diagnostics, Department of Genetics, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, The Netherlands
| | - Nanda M. Verhoeven-Duif
- Section Metabolic Diagnostics, Department of Genetics, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, The Netherlands
| | - Judith J.M. Jans
- Section Metabolic Diagnostics, Department of Genetics, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, The Netherlands
- Correspondence: (H.A.H.); (J.J.M.J.)
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Erratum: Ismail, I.T.; et al. Inborn Errors of Metabolism in the Era of Untargeted Metabolomics and Lipidomics. Metabolites 2019, 9, 242. Metabolites 2020; 10:metabo10010025. [PMID: 31935925 PMCID: PMC7022264 DOI: 10.3390/metabo10010025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 12/30/2019] [Indexed: 11/16/2022] Open
Abstract
The authors wish to make the following correction to this paper [...]
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38
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Ismail IT, Showalter MR, Fiehn O. Inborn Errors of Metabolism in the Era of Untargeted Metabolomics and Lipidomics. Metabolites 2019; 9:metabo9100242. [PMID: 31640247 PMCID: PMC6835511 DOI: 10.3390/metabo9100242] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Revised: 10/11/2019] [Accepted: 10/15/2019] [Indexed: 12/30/2022] Open
Abstract
Inborn errors of metabolism (IEMs) are a group of inherited diseases with variable incidences. IEMs are caused by disrupting enzyme activities in specific metabolic pathways by genetic mutations, either directly or indirectly by cofactor deficiencies, causing altered levels of compounds associated with these pathways. While IEMs may present with multiple overlapping symptoms and metabolites, early and accurate diagnosis of IEMs is critical for the long-term health of affected subjects. The prevalence of IEMs differs between countries, likely because different IEM classifications and IEM screening methods are used. Currently, newborn screening programs exclusively use targeted metabolic assays that focus on limited panels of compounds for selected IEM diseases. Such targeted approaches face the problem of false negative and false positive diagnoses that could be overcome if metabolic screening adopted analyses of a broader range of analytes. Hence, we here review the prospects of using untargeted metabolomics for IEM screening. Untargeted metabolomics and lipidomics do not rely on predefined target lists and can detect as many metabolites as possible in a sample, allowing to screen for many metabolic pathways simultaneously. Examples are given for nontargeted analyses of IEMs, and prospects and limitations of different metabolomics methods are discussed. We conclude that dedicated studies are needed to compare accuracy and robustness of targeted and untargeted methods with respect to widening the scope of IEM diagnostics.
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Affiliation(s)
- Israa T Ismail
- National Liver Institute, Menoufia University, Shebeen El Kom 55955, Egypt.
- NIH West Coast Metabolomics Center, University of California Davis, Davis, CA 95616, USA.
| | - Megan R Showalter
- NIH West Coast Metabolomics Center, University of California Davis, Davis, CA 95616, USA.
| | - Oliver Fiehn
- NIH West Coast Metabolomics Center, University of California Davis, Davis, CA 95616, USA.
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Glinton KE, Elsea SH. Untargeted Metabolomics for Autism Spectrum Disorders: Current Status and Future Directions. Front Psychiatry 2019; 10:647. [PMID: 31551836 PMCID: PMC6746843 DOI: 10.3389/fpsyt.2019.00647] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 08/12/2019] [Indexed: 12/20/2022] Open
Abstract
Autism spectrum disorders (ASDs) are a group of neurodevelopment disorders characterized by childhood onset deficits in social communication and interaction. Although the exact etiology of most cases of ASDs is unknown, a portion has been proposed to be associated with various metabolic abnormalities including mitochondrial dysfunction, disorders of cholesterol metabolism, and folate abnormalities. Targeted biochemical testing like plasma amino acid and acylcarnitine profiles have demonstrated limited utility in helping to diagnose and manage such patients. Untargeted metabolomics has emerged, however, as a promising tool in screening for underlying biochemical abnormalities and managing treatment and as a means of investigating possible novel biomarkers for the disorder. Here, we review the principles and methodology behind untargeted metabolomics, recent pilot studies utilizing this technology, and areas in which it may be integrated into the care of children with this disorder in the future.
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Affiliation(s)
- Kevin E. Glinton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
| | - Sarah H. Elsea
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, United States
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40
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Kilk K. Metabolomics for Animal Models of Rare Human Diseases: An Expert Review and Lessons Learned. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2019; 23:300-307. [PMID: 31120384 DOI: 10.1089/omi.2019.0065] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Rare diseases occur with a frequency ≤1:1500-1:2500 depending on the location and applicable definitions across countries. Although individually rare, they collectively affect as much as 4-8% of population imposing a large burden on public health. Rarity in prevalence means prolonged path to accurate diagnosis, lack of treatment options, and also limited chances for preclinical studies of pathogenesis. I discuss in this expert review (1) what metabolomics, as a high throughput systems sciences technology, offers for rare disease studies, (2) why animal models are important for the study of rare human diseases and what should be kept in mind while using animal models, and finally, (3) provide examples of recent research to highlight how metabolomics on animal models of rare diseases perform, and how these results can lead to the knowhow, which raises genome, metabolome, and phenotype integration to a whole new level. In sum, metabolomics has been for years in clinical use for diagnosis of certain types of rare diseases. Determination of pathogenesis of more complex diseases and testing of treatment strategies is where animal models and systems biology analytical approaches are necessary. From gathered data, it is possible to go back to diagnostic and prognostic markers for rare diseases, which so far lack reliable and robust diagnosis and therapeutic options. In the future, a major challenge is to reveal the links between genotype, metabolism, and phenotype. Rare diseases could be the key in that process.
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Affiliation(s)
- Kalle Kilk
- Department of Biochemistry, Institute of Biomedicine and Translational Medicine, University of Tartu, Tartu, Estonia
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