scholarly journals Tandem Mass Spectrometry Has a Larger Analytical Range than Fluorescence Assays of Lysosomal Enzymes: Application to Newborn Screening and Diagnosis of Mucopolysaccharidoses Types II, IVA, and VI

2015 ◽  
Vol 61 (11) ◽  
pp. 1363-1371 ◽  
Author(s):  
Arun Babu Kumar ◽  
Sophia Masi ◽  
Farideh Ghomashchi ◽  
Naveen Kumar Chennamaneni ◽  
Makoto Ito ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Newborn Screening ◽  
Lysosomal Enzymes ◽  
Lysosomal Storage Diseases ◽  
Tandem Mass ◽  
Lysosomal Storage ◽  
Storage Diseases ◽  
Mps Ii ◽  
Analytical Range ◽  
Screening And Diagnosis

Abstract BACKGROUND There is interest in newborn screening and diagnosis of lysosomal storage diseases because of the development of treatment options that improve clinical outcome. Assays of lysosomal enzymes with high analytical range (ratio of assay response from the enzymatic reaction divided by the assay response due to nonenzymatic processes) are desirable because they are predicted to lead to a lower rate of false positives in population screening and to more accurate diagnoses. METHODS We designed new tandem mass spectrometry (MS/MS) assays that give the largest analytical ranges reported to date for the use of dried blood spots (DBS) for detection of mucopolysaccharidoses type II (MPS-II), MPS-IVA, and MPS-VI. For comparison, we carried out fluorometric assays of 6 lysosomal enzymes using 4-methylumbelliferyl (4MU)-substrate conjugates. RESULTS The MS/MS assays for MPS-II, -IVA, and -VI displayed analytical ranges that are 1–2 orders of magnitude higher than those for the corresponding fluorometric assays. The relatively small analytical ranges of the 4MU assays are due to the intrinsic fluorescence of the 4MU substrates, which cause high background in the assay response. CONCLUSIONS These highly reproducible MS/MS assays for MPS-II, -IVA, and -VI can support multiplex newborn screening of these lysosomal storage diseases. MS/MS assays of lysosomal enzymes outperform 4MU fluorometric assays in terms of analytical range. Ongoing pilot studies will allow us to gauge the impact of the increased analytical range on newborn screening performance.

scholarly journals Pilot study of newborn screening for six lysosomal storage diseases using Tandem Mass Spectrometry

2016 ◽  
Vol 118 (4) ◽  
pp. 304-309 ◽  
Author(s):  
Susan Elliott ◽  
Norman Buroker ◽  
Jason J. Cournoyer ◽  
Anna M. Potier ◽  
Joseph D. Trometer ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Pilot Study ◽  
Tandem Mass Spectrometry ◽  
Newborn Screening ◽  
Lysosomal Storage Diseases ◽  
Tandem Mass ◽  
Lysosomal Storage ◽  
Storage Diseases

scholarly journals Multiplex Tandem Mass Spectrometry Enzymatic Activity Assay for Newborn Screening of the Mucopolysaccharidoses and Type 2 Neuronal Ceroid Lipofuscinosis

2017 ◽  
Vol 63 (6) ◽  
pp. 1118-1126 ◽  
Author(s):  
Yang Liu ◽  
Fan Yi ◽  
Arun Babu Kumar ◽  
Naveen Kumar Chennamaneni ◽  
Xinying Hong ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Newborn Screening ◽  
Neuronal Ceroid Lipofuscinosis ◽  
Lysosomal Storage Diseases ◽  
Tandem Mass ◽  
Lysosomal Storage ◽  
Storage Diseases ◽  
Ceroid Lipofuscinosis

Abstract BACKGROUND We expanded the use of tandem mass spectrometry combined with liquid chromatography (LC-MS/MS) for multiplex newborn screening of seven lysosomal enzymes in dried blood spots (DBS). The new assays are for enzymes responsible for the mucopolysaccharidoses (MPS-I, -II, -IIIB, -IVA, -VI, and -VII) and type 2 neuronal ceroid lipofuscinosis (LINCL). METHODS New substrates were prepared and characterized for tripeptidyl peptidase 1 (TPP1), α-N-acetylglucosaminidase (NAGLU), and lysosomal β-glucuronidase (GUSB). These assays were combined with previously developed assays to provide a multiplex LC-MS/MS assay of 7 lysosomal storage diseases. Multiple reaction monitoring of ion dissociations for enzyme products and deuterium-labeled internal standards was used to quantify the enzyme activities. RESULTS Deidentified DBS samples from 62 nonaffected newborns were analyzed to simultaneously determine (run time 2 min per DBS) the activities of TPP1, NAGLU, and GUSB, along with those for α-iduronidase (IDUA), iduronate-2-sulfatase (I2S), N-acetylgalactosamine-6-sulfatase (GALNS), and N-acetylgalactosamine-4-sulfatase (ARSB). The activities measured in the 7-plex format showed assay response-to-blank-activity ratios (analytical ranges) of 102–909 that clearly separated healthy infants from affected children. CONCLUSIONS The new multiplex assay provides a robust comprehensive newborn screening assay for the mucopolysaccharidoses. The method has been expanded to include additional lysosomal storage diseases.

scholarly journals Newborn Screening for Lysosomal Storage Diseases

2015 ◽  
Vol 61 (2) ◽  
pp. 335-346 ◽  
Author(s):  
Michael H Gelb ◽  
C Ronald Scott ◽  
Frantisek Turecek
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Newborn Screening ◽  
Lysosomal Storage Diseases ◽  
Small Scale ◽  
Screening Methods ◽  
Tandem Mass ◽  
Lysosomal Storage ◽  
Storage Diseases ◽  
Direct Assay

Abstract BACKGROUND There is worldwide interest in newborn screening for lysosomal storage diseases because of the development of treatment options that give better results when carried out early in life. Screens with high differentiation between affected and nonaffected individuals are critical because of the large number of potential false positives. CONTENT This review summarizes 3 screening methods: (a) direct assay of enzymatic activities using tandem mass spectrometry or fluorometry, (b) immunocapture-based measurement of lysosomal enzyme abundance, and (c) measurement of biomarkers. Assay performance is compared on the basis of small-scale studies as well as on large-scale pilot studies of mass spectrometric and fluorometric screens. SUMMARY Tandem mass spectrometry and fluorometry techniques for direct assay of lysosomal enzymatic activity in dried blood spots have emerged as the most studied approaches. Comparative mass spectrometry vs fluorometry studies show that the former better differentiates between nonaffected vs affected individuals. This in turn leads to a manageable number of screen positives that can be further evaluated with second-tier methods.

Development and Validation of Leukocyte Enzyme Activity Assay by LC-MS/MS for Diagnosis of Krabbe Disease and Other Lysosomal Storage Diseases

2020 ◽  
Vol 154 (Supplement_1) ◽  
pp. S16-S16
Author(s):  
Hsuan-Chieh Liao ◽  
Laura Mitchell ◽  
Katerina Sadilkova ◽  
Jane Dickerson ◽  
Rhona Jack ◽  
...  
Keyword(s):  
Enzyme Activity ◽  
Liquid Chromatography ◽  
Lysosomal Enzymes ◽  
Internal Standard ◽  
Lysosomal Storage Diseases ◽  
Krabbe Disease ◽  
Tandem Mass ◽  
Lysosomal Storage ◽  
Mass Detection ◽  
Storage Diseases

Abstract Background Deficiency of the lysosomal enzyme galactosylcerebrosidase (GALC) causes Krabbe disease. The diagnosis for Krabbe disease includes measurement of GALC enzymatic activity by radioisotope assay or accumulation of metabolite psychosine. To improve current diagnostic workflow and assay performance, we developed and validated a leukocyte enzymatic assay by using liquid chromatography tandem mass spectrometry (LC-MS/MS) for lysosomal storage diseases. Methods Leukocytes were separated and extracted from whole blood samples, and total protein was quantitated by BCA method. Commercialized and multiplexed substrates, internal standards, and buffer were incubated with cell lysates. The lysosomal enzymes in leukocytes metabolized the artificial substrate into product which is structurally identical to the internal standard. Liquid-liquid extraction was performed and supernatant was dried down and reconstituted. Liquid chromatography separation was achieved by Waters CSH C18, 2.1 x 50 mm column and Acquity UPLC system. A Waters Xevo TQS tandem mass spectrometer was used for mass detection. Results Enzymatic reaction products for six lysosomal enzymes were chromatographically resolved from substrate breakdown products through 3.5 minutes gradient liquid chromatography. Intra-assay imprecision was determined by 11 replicates of samples containing low and high concentration (CV<15%). Carryover was determined by assaying triplicates of cell lysate-free cocktails directly after injection of high enzyme activity sample (less than 0.1%). No matrix effect was found. The GALC enzyme activity was calculated and standardized by corresponding product and internal standard ratios from 5-point standard curve. The range of enzyme activity from three, known affected patients is 0.01–0.07 (nmol/hr/mg protein); whereas, two identified carriers had enzyme activate in the range of 0.14–0.40 (nmol/hr/mg protein). The reference interval was established from 63 residual, unaffected samples and was 0.12–5.97 (1.44±1.44) nmol/hr/mg protein. Conclusions A simple and multiplexed LC-MS/MS assay was developed which can measure small amounts of residual GALC enzyme activity in leukocytes. This confirmatory assay will aid in the diagnosis and prognosis (i.e. differentiate disease severity) of Krabbe disease and other lysosomal storage disorders.

scholarly journals Diagnosing lysosomal storage diseases in a Brazilian non-newborn population by tandem mass spectrometry

Clinics ◽  
2013 ◽  
Vol 68 (11) ◽  
pp. 1469-1473 ◽  
Author(s):  
GD Brand ◽  
HC Matos ◽  
GC Cruz ◽  
NC Fontes ◽  
M Buzzi ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Tandem Mass Spectrometry ◽  
Lysosomal Storage Diseases ◽  
Tandem Mass ◽  
Lysosomal Storage ◽  
Storage Diseases
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