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De Biase I, Tortorelli S, Kratz L, J Steinberg S, Cusmano-Ozog K, Braverman N; ACMG Laboratory Quality Assurance Committee. Laboratory diagnosis of disorders of peroxisomal biogenesis and function: a technical standard of the American College of Medical Genetics and Genomics (ACMG). Genet Med 2020; 22:686-97. [PMID: 31822849 DOI: 10.1038/s41436-019-0713-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 11/18/2019] [Accepted: 11/18/2019] [Indexed: 01/02/2023] Open
Abstract
Peroxisomal disorders are a clinically and genetically heterogeneous group of diseases caused by defects in peroxisomal biogenesis or function, usually impairing several metabolic pathways. Peroxisomal disorders are rare; however, the incidence may be underestimated due to the broad spectrum of clinical presentations. The inclusion of X-linked adrenoleukodystrophy to the Recommended Uniform Screening Panel for newborn screening programs in the United States may increase detection of this and other peroxisomal disorders. The current diagnostic approach relies heavily on biochemical genetic tests measuring peroxisomal metabolites, including very long-chain and branched-chain fatty acids in plasma and plasmalogens in red blood cells. Molecular testing can confirm biochemical findings and identify the specific genetic defect, usually utilizing a multiple-gene panel or exome/genome approach. When next-generation sequencing is used as a first-tier test, evaluation of peroxisome metabolism is often necessary to assess the significance of unknown variants and establish the extent of peroxisome dysfunction. This document provides a resource for laboratories developing and implementing clinical biochemical genetic testing for peroxisomal disorders, emphasizing technical considerations for sample collection, test performance, and result interpretation. Additionally, considerations on confirmatory molecular testing are discussed.
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Kumar AB, Hong X, Yi F, Wood T, Gelb MH. Tandem mass spectrometry-based multiplex assays for α-mannosidosis and fucosidosis. Mol Genet Metab 2019; 127:207-211. [PMID: 31235216 PMCID: PMC6710107 DOI: 10.1016/j.ymgme.2019.05.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Revised: 05/24/2019] [Accepted: 05/30/2019] [Indexed: 02/08/2023]
Abstract
Multiplex tandem mass spectrometry (MS/MS)-based enzyme activity assays for newborn screening (NBS) and diagnosis of lysosomal storage diseases (LSDs) in newborns, using dried blood spots (DBS) on newborn screening cards, have garnered much attention due to its sensitivity, high precision, and the capability to screen for an unprecedented number of diseases in a single assay. Herein we report the development of MS/MS-based enzyme assays for the diagnosis of α-mannosidosis and fucosidosis. These new protocols are able to distinguish untreated patients from random newborns, carriers and a post-bone marrow transplant patient. We have successfully multiplexed the α-mannosidosis assay with a multiplex MS/MS assay for the screening and diagnosis of other LSDs, namely Fabry, Pompe, MPS I, Gaucher, Niemann-Pick-A/B, and Krabbe diseases. Additionally, we also multiplexed the fucosidosis NBS assay with a 5-plex assay that tests for MPS-II, MPS-IIIB, MPS-IVA, MPS-VI and MPS-VII.
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Affiliation(s)
- Arun Babu Kumar
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA.
| | - Xinying Hong
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Fan Yi
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Tim Wood
- Greenwood Genetic Center, Greenwood, SC 29646, USA
| | - Michael H Gelb
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA.
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Hsu RH, Chien YH, Hwu WL, Chang IF, Ho HC, Chou SP, Huang TM, Lee NC. Genotypic and phenotypic correlations of biotinidase deficiency in the Chinese population. Orphanet J Rare Dis 2019; 14:6. [PMID: 30616616 PMCID: PMC6323711 DOI: 10.1186/s13023-018-0992-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Accepted: 12/28/2018] [Indexed: 12/29/2022] Open
Abstract
Biotinidase deficiency is an autosomal recessive disorder that affects the endogenous recycling and release of biotin from dietary protein. This disease was thought to be rare in East Asia. In this report, we delineate the phenotype of biotinidase deficiency in our cohort. The genotypes and phenotypes of patients diagnosed with biotinidase deficiency from a medical center were reviewed. The clinical manifestations, laboratory findings, and molecular test results were retrospectively analyzed. A total of 6 patients were evaluated. Three patients (50%) were diagnosed because of a clinical illness, and the other three (50%) were identified by newborn screening. In all patients, the molecular results confirmed the BTD mutation. The three patients with clinical manifestations had an onset of seizure at the age of 2 to 3 months. Two patients had respiratory problems (one with apnea under bilevel positive airway pressure (BiPAP) therapy at night, and the other with laryngomalacia). Hearing loss and eye problems were found in one patient. Interestingly, cutaneous manifestations including skin eczema, alopecia, and recurrent fungal infection were less commonly seen compared to cases in the literature. None of the patients identified by the newborn screening program developed symptoms. Our findings highlight differences in the genotype and phenotype compared with those in Western countries. Patients with biotinidase deficiency benefit from newborn screening programs for early detection and management.
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Affiliation(s)
- Rai-Hseng Hsu
- Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
- Department of Pediatrics, Taipei Medical University Hospital, No. 252, Wuxing St, Xinyi Dist., Taipei, 11031 Taiwan
| | - Yin-Hsiu Chien
- Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
| | - Wuh-Liang Hwu
- Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
| | - I-Fan Chang
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
| | - Hui-Chen Ho
- Taipei Institute of Pathology, No.146, Sec.3, Chongqing N. Rd., Datong Dist., Taipei, 10374 Taiwan
| | - Shi-Ping Chou
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
| | - Tzu-Ming Huang
- Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
| | - Ni-Chung Lee
- Department of Medical Genetics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
- Department of Pediatrics, National Taiwan University Hospital, No. 8, Chung-Shan S. Rd., Zhongzheng Dist., Taipei, 10041 Taiwan
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Ohira M, Okuyama T, Mashima R. Quantification of 11 enzyme activities of lysosomal storage disorders using liquid chromatography-tandem mass spectrometry. Mol Genet Metab Rep 2018; 17:9-15. [PMID: 30211004 DOI: 10.1016/j.ymgmr.2018.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2018] [Revised: 08/29/2018] [Accepted: 08/30/2018] [Indexed: 11/23/2022] Open
Abstract
Lysosomal storage disorders (LSDs) are characterized by the accumulation of lipids, glycolipids, oligosaccharides, mucopolysaccharides, and other biological substances because of the pathogenic deficiency of lysosomal enzymes. Such diseases are rare; thus, a multiplex assay for these disorders is effective for the identification of affected individuals during the presymptomatic period. Previous studies have demonstrated that such assays can be performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with multiple reaction monitoring (MRM) detection. An assay procedure to quantify the activity of 11 enzymes associated with LSDs was provided. First, a validation study was performed using dried blood spot (DBS) samples with 100% and 5% enzyme activity for quality control (QC). Under the assay condition, the analytical range, defined as the ratio of the peak area of the enzyme reaction products from the DBS for QC with 100% enzyme activity to that from the filter paper blank sample, was between 14 for GALN and 4561 for GLA. Based on these results, the distribution of the enzyme activity for the 11 LSD enzymes was further examined. Consistent with the previous data, the enzyme activity exhibited a bell-shaped distribution with a single peak. The averaged enzyme activity for the healthy neonates was as follows: GLA, 3.80 ± 1.6; GAA, 10.6 ± 4.8; IDUA, 6.4 ± 2.3; ABG, 8.6 ± 3.1; ASM, 3.3 ± 1.1; GALC, 2.8 ± 1.3; ID2S, 16.7 ± 6.1; GALN, 1.2 ± 0.5; ARSB, 17.0 ± 8.7; NAGLU, 4.6 ± 1.5; and GUSB, 46.6 ± 19.0 μmol/h/L (mean ± SD, n = 200). In contrast, the enzyme activity in disease-affected individuals was lower than the minimum enzyme activity in healthy neonates. The results demonstrate that the population of disease-affected individuals was distinguished from that of healthy individuals by the use of LC-MS/MS.
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