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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Takeuchi T, Nishino K, Itokawa Y. Improved determination of transketolase activity in erythrocytes. Clin Chem 1984; 30:658-61. [PMID: 6713626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We describe a new and better method for determining transketolase (EC 2.2.1.1) activity in human erythrocytes. Heating the hemolysate (55 degrees C, 5 min) inactivates transaldolase (EC 2.2.1.2), the enzyme that catalyzes the formation of fructose 6-phosphate and erythrose 4-phosphate from sedoheptulose 7-phosphate and glyceraldehyde 3-phosphate. The net effect is that the quantity of sedoheptulose 7-phosphate formed more precisely represents the transketolase activity, which is unaffected under these conditions. Use of ribosephosphate isomerase (EC 5.3.1.6) and ribulose-phosphate 3-epimerase (EC 5.1.3.1) to establish an equilibrium among the pentoses allowed us to confirm the stoichiometry of the transketolase reaction. We also discuss the effect of thiamin pyrophosphate, which is used to reflect thiamin deficiency.
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