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Bernhard E, Nitschke Y, Khursigara G, Sabbagh Y, Wang Y, Rutsch F. A Reference Range for Plasma Levels of Inorganic Pyrophosphate in Children Using the ATP Sulfurylase Method. J Clin Endocrinol Metab 2022; 107:109-118. [PMID: 34498693 PMCID: PMC8684482 DOI: 10.1210/clinem/dgab615] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Indexed: 11/19/2022]
Abstract
PURPOSE Generalized arterial calcification of infancy, pseudoxanthoma elasticum, autosomal recessive hypophosphatemic rickets type 2, and hypophosphatasia are rare inherited disorders associated with altered plasma levels of inorganic pyrophosphate (PPi). In this study, we aimed to establish a reference range for plasma PPi in the pediatric population, which would be essential to support its use as a biomarker in children with mineralization disorders. METHODS Plasma samples were collected from 200 children aged 1 day to 18 years who underwent blood testing for medical conditions not affecting plasma PPi levels. PPi was measured in proband plasma utilizing a validated adenosine triphosphate (ATP) sulfurylase method. RESULTS The analytical sensitivity of the ATP sulfurylase assay consisted of 0.15 to 10 µM PPi. Inter- and intra-assay coefficients of variability on identical samples were below 10%. The standard range of PPi in the blood plasma of children and adolescents aged 0 to 18 years was calculated as 2.36 to 4.44 µM, with a median of 3.17 µM, with no difference between male and female probands. PPi plasma levels did not differ significantly in different pediatric age groups. MAIN CONCLUSIONS Our results yielded no noteworthy discrepancy to the reported standard range of plasma PPi in adults (2-5 µM). We propose the described ATP sulfurylase method as a diagnostic tool to measure PPi levels in plasma as a biomarker in the pediatric population.
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Affiliation(s)
- Eva Bernhard
- Department of General Pediatrics, Muenster University Children’s Hospital, Muenster, Germany
| | - Yvonne Nitschke
- Department of General Pediatrics, Muenster University Children’s Hospital, Muenster, Germany
| | | | | | - Yongbao Wang
- National Jewish Health Advanced Diagnostic Laboratories, Denver, CO, USA
| | - Frank Rutsch
- Department of General Pediatrics, Muenster University Children’s Hospital, Muenster, Germany
- Correspondence: Frank Rutsch, MD, Department of General Pediatrics, Muenster University Children’s Hospital, Albert-Schweitzer-Campus 1, Gebäude A1, D-48149 Muenster, Germany.
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Ferreira CR, Hackbarth ME, Ziegler SG, Pan KS, Roberts MS, Rosing DR, Whelpley MS, Bryant JC, Macnamara EF, Wang S, Müller K, Hartley IR, Chew EY, Corden TE, Jacobsen CM, Holm IA, Rutsch F, Dikoglu E, Chen MY, Mughal MZ, Levine MA, Gafni RI, Gahl WA. Prospective phenotyping of long-term survivors of generalized arterial calcification of infancy (GACI). Genet Med 2020; 23:396-407. [PMID: 33005041 PMCID: PMC7867608 DOI: 10.1038/s41436-020-00983-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 09/15/2020] [Accepted: 09/18/2020] [Indexed: 02/07/2023] Open
Abstract
PURPOSE Generalized arterial calcification of infancy (GACI), characterized by vascular calcifications that are often fatal shortly after birth, is usually caused by deficiency of ENPP1. A small fraction of GACI cases result from deficiency of ABCC6, a membrane transporter. The natural history of GACI survivors has not been established in a prospective fashion. METHODS We performed deep phenotyping of 20 GACI survivors. RESULTS Sixteen of 20 subjects presented with arterial calcifications, but only 5 had residual involvement at the time of evaluation. Individuals with ENPP1 deficiency either had hypophosphatemic rickets or were predicted to develop it by 14 years of age; 14/16 had elevated intact FGF23 levels (iFGF23). Blood phosphate levels correlated inversely with iFGF23. For ENPP1-deficient individuals, the lifetime risk of cervical spine fusion was 25%, that of hearing loss was 75%, and the main morbidity in adults was related to enthesis calcification. Four ENPP1-deficient individuals manifested classic skin or retinal findings of PXE. We estimated the minimal incidence of ENPP1 deficiency at ~1 in 200,000 pregnancies. CONCLUSION GACI appears to be more common than previously thought, with an expanding spectrum of overlapping phenotypes. The relationships among decreased ENPP1, increased iFGF23, and rickets could inform future therapies.
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Affiliation(s)
- Carlos R Ferreira
- Medical Genomics and Metabolic Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Mary E Hackbarth
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Shira G Ziegler
- Departments of Pediatrics and Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Kristen S Pan
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Mary S Roberts
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Douglas R Rosing
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Margaret S Whelpley
- Cardiovascular Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Joy C Bryant
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ellen F Macnamara
- Undiagnosed Diseases Program, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | | | | | - Iris R Hartley
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Emily Y Chew
- Division of Epidemiology and Clinical Applications, Clinical Trials Branch, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Timothy E Corden
- Department of Pediatrics, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Christina M Jacobsen
- Divisions of Endocrinology and Genetics and Genomics, Boston Children's Hospital, Boston, MA, USA.,Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Ingrid A Holm
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA.,Division of Genetics and Genomics and the Manton Center for Orphan Diseases Research, Boston Children's Hospital, Boston, MA, USA
| | - Frank Rutsch
- Department of General Pediatrics, Muenster University Children's Hospital, Muenster, Germany
| | - Esra Dikoglu
- Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Marcus Y Chen
- Cardiovascular CT Laboratory, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - M Zulf Mughal
- Department of Paediatric Endocrinology, Royal Manchester Children's Hospital, Manchester University Hospital's NHS Trust, Manchester, UK
| | - Michael A Levine
- Division of Endocrinology and Diabetes, The Children's Hospital of Philadelphia and the Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Rachel I Gafni
- Skeletal Disorders and Mineral Homeostasis Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - William A Gahl
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
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