Hanneke A Haijes1, Monique G M de Sain-van der Velden2, Hubertus C M T Prinsen2, Anke P Willems2, Maria van der Ham2, Johan Gerrits2, Madeline H Couse3, Jan M Friedman3, Clara D M van Karnebeek4, Kathryn A Selby5, Peter M van Hasselt6, Nanda M Verhoeven-Duif2, Judith J M Jans7. 1. Section Metabolic Diagnostics, Department of Genetics, Utrecht University, University Medical Centre Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands; Section Metabolic Diseases, Department of Child Health, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, the Netherlands. Electronic address: h.a.siepel-3@umcutrecht.nl. 2. Section Metabolic Diagnostics, Department of Genetics, Utrecht University, University Medical Centre Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands. 3. Medical Genetics Research Unit,Children's and Women's Hospital, University of British Columbia Department of Medical Genetics, 4500 Oak Street, Vancouver, BC V6H 3N1, Canada. 4. Departments of Pediatrics and Clinical Genetics, Emma Children's Hospital, University of Amsterdam, Amsterdam University Medical Centers, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands; Department of Pediatrics, Children's and Women's Hospital, University of British Columbia, 4500 Oak Street, Vancouver, BC V6H 3N1, Canada; Centre for Molecular Medicine and Therapeutics, BC Children's Research Institute, University of British Columbia, 4500 Oak Street, Vancouver, BC V6H 3N1, Canada. 5. Department of Pediatrics, Children's and Women's Hospital, University of British Columbia, 4500 Oak Street, Vancouver, BC V6H 3N1, Canada. 6. Section Metabolic Diseases, Department of Child Health, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht University, Lundlaan 6, 3584 EA Utrecht, the Netherlands. 7. Section Metabolic Diagnostics, Department of Genetics, Utrecht University, University Medical Centre Utrecht, Lundlaan 6, 3584 EA Utrecht, the Netherlands. Electronic address: J.J.M.Jans@umcutrecht.nl.
Abstract
BACKGROUND: NGLY1-CDDG is a congenital disorder of deglycosylation caused by a defective peptide:N-glycanase (PNG). To date, all but one of the reported patients have been diagnosed through whole-exome or whole-genome sequencing, as no biochemical marker was available to identify this disease in patients. Recently, a potential urinary biomarker was reported, but the data presented suggest that this marker may be excreted intermittently. METHODS: In this study, we performed untargeted direct-infusion high-resolution mass spectrometry metabolomics in seven dried blood spots (DBS) from four recently diagnosed NGLY1-CDDG patients, to test for small-molecule biomarkers, in order to identify a potential diagnostic marker. Results were compared to 125 DBS of healthy controls and to 238 DBS of patients with other diseases. RESULTS: We identified aspartylglycosamine as the only significantly increased compound with a median Z-score of 4.8 (range: 3.8-8.5) in DBS of NGLY1-CDDG patients, compared to a median Z-score of -0.1 (range: -2.1-4.0) in DBS of healthy controls and patients with other diseases. DISCUSSION: The increase of aspartylglycosamine can be explained by lack of function of PNG. PNG catalyzes the cleavage of the proximal N-acetylglucosamine residue of an N-glycan from the asparagine residue of a protein, a step in the degradation of misfolded glycoproteins. PNG deficiency results in a single N-acetylglucosamine residue left attached to the asparagine residue which results in free aspartylglycosamine when the glycoprotein is degraded. Thus, we here identified aspartylglycosamine as the first potential small-molecule biomarker in DBS for NGLY1-CDDG, making a biochemical diagnosis for NGLY1-CDDG potentially feasible.
BACKGROUND:NGLY1-CDDG is a congenital disorder of deglycosylation caused by a defective peptide:N-glycanase (PNG). To date, all but one of the reported patients have been diagnosed through whole-exome or whole-genome sequencing, as no biochemical marker was available to identify this disease in patients. Recently, a potential urinary biomarker was reported, but the data presented suggest that this marker may be excreted intermittently. METHODS: In this study, we performed untargeted direct-infusion high-resolution mass spectrometry metabolomics in seven dried blood spots (DBS) from four recently diagnosed NGLY1-CDDGpatients, to test for small-molecule biomarkers, in order to identify a potential diagnostic marker. Results were compared to 125 DBS of healthy controls and to 238 DBS of patients with other diseases. RESULTS: We identified aspartylglycosamine as the only significantly increased compound with a median Z-score of 4.8 (range: 3.8-8.5) in DBS of NGLY1-CDDGpatients, compared to a median Z-score of -0.1 (range: -2.1-4.0) in DBS of healthy controls and patients with other diseases. DISCUSSION: The increase of aspartylglycosamine can be explained by lack of function of PNG. PNG catalyzes the cleavage of the proximal N-acetylglucosamine residue of an N-glycan from the asparagine residue of a protein, a step in the degradation of misfolded glycoproteins. PNG deficiency results in a single N-acetylglucosamine residue left attached to the asparagine residue which results in free aspartylglycosamine when the glycoprotein is degraded. Thus, we here identified aspartylglycosamine as the first potential small-molecule biomarker in DBS for NGLY1-CDDG, making a biochemical diagnosis for NGLY1-CDDG potentially feasible.
Authors: Hanneke A Haijes; Maria van der Ham; Hubertus C M T Prinsen; Melissa H Broeks; Peter M van Hasselt; Monique G M de Sain-van der Velden; Nanda M Verhoeven-Duif; Judith J M Jans Journal: Int J Mol Sci Date: 2020-02-01 Impact factor: 5.923
Authors: William F Mueller; Lei Zhu; Brandon Tan; Selina Dwight; Brendan Beahm; Matt Wilsey; Thomas Wechsler; Justin Mak; Tina Cowan; Jake Pritchett; Eric Taylor; Brett E Crawford Journal: J Biochem Date: 2022-02-21 Impact factor: 3.387