Fluorimetric assays for N-acetylgalactosamine-6-sulfatase and arylsulfatase B based on the natural substrates for confirmation of mucopolysaccharidoses types IVA and VI

Kumar, Arun; Spáčil, Zdeněk; Ghomashchi, Farideh; Masi, Sophia; Sumida, Tomoki; Ito, Makoto; Tureček, František; Scott, C. Ronald; Gelb, Michael H.

doi:10.1016/j.cca.2015.08.010

Cited by 13 publications

(13 citation statements)

References 6 publications

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“…Moreover, sets 6–8 gave highly similar results showing independence of the assay from the length of the modifier. As the observed activities of >10 μM/h are significantly higher than or at least similar to previously reported data using MS/MS-based 20,26 or fluorometric methods, 54,55 we aimed to test our GALNS click substrates in a clinically more relevant setup. Therefore, we have analyzed DBS of 9 confirmed MPS IVa patients in comparison to randomly selected newborns (all anonymized).…”

Section: Resultssupporting

confidence: 67%

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Rapid and Modular Assembly of Click Substrates To Assay Enzyme Activity in the Newborn Screening of Lysosomal Storage Disorders

et al. 2018

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Synthetic substrates play a pivotal role in the development of enzyme assays for medical diagnostics. However, the preparation of these chemical tools often requires multistep synthetic procedures complicating structural optimization and limiting versatility. In particular, substrates for enzyme assays based on tandem mass spectrometry need to be designed and optimized to fulfill the requirements to finally enable the development of robust diagnostic assays. In addition, isotope-labeled standards need to be prepared to facilitate accurate quantification of enzyme assay products. Here we report the development of a building block strategy for rapid and modular assembly of enzyme substrates using click chemistry as a key step. These click substrates are made up of a sugar moiety as enzyme responsive unit, a linker that can easily be isotope-labeled for the synthesis of internal standards, and a modifier compound that can readily be exchanged for structural optimization and analytical/diagnostic tuning. Moreover, the building block assembly eliminates the need for extensive optimization of different glycosylation reactions as it enables the divergent synthesis of substrates using a clickable enzyme responsive unit. The outlined strategy has been applied to obtain a series of synthetic α-l-iduronates and sulfated β-d-galactosides as substrates for assaying α-l-iduronidase and N-acetylgalactosamine-6-sulfate sulfatase, enzymes related to the lysosomal storage disorders mucopolysaccharidosis type I and type IVa, respectively. Selected click substrates were finally shown to be suitable to assay enzyme activities in dried blood spot samples from affected patients and random newborns.

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Section: Resultssupporting

confidence: 67%

“…52,53 GALNS has been assayed in dried blood spots to screen for MPS IVa using fluorometric and LC-MS/MS-based methods. 20,26,54−56…”

Section: Resultsmentioning

confidence: 99%

Rapid and Modular Assembly of Click Substrates To Assay Enzyme Activity in the Newborn Screening of Lysosomal Storage Disorders

et al. 2018

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“…The calculation of the analytical range of this GALNS assay with DBS was not possible because the assay responses for the blanks were not stated (7). However, we can say that the mean GALNS activity measured for 50 random newborn DBS with 3 mmol/L 4MU-GalNAc-6-S is 3.8 μ mol · h −1 · L −1 (22) compared to 0.28 μ mol · h −1 · L −1 reported using 10 mmol/L 4MU-Gal-6-S (7). This suggests that GALNS is approximately 44-fold more active on 4MU-GalNAc-6-S vs 4MU-Gal-6-S, which is consistent with our MS/MS data (see online Supplemental Table 3).…”

Section: Discussionmentioning

confidence: 76%

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

Kumar¹,

Masi²,

Ghomashchi³

et al. 2015

Clinical Chemistry

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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.

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“…These disease-specific oligosaccharides can be used to monitor response to therapeutic interventions [48]. A fluorometric assay for N -acetylgalactosamine-6-sulfate (GALNS) has been developed for the differential diagnosis of MPS IVA; however, the data suggest this will not be robust enough for newborn screening [139]. Ongoing pilot studies of more accurate tandem mass spectrometry assays and their application to newborn screening have been described [140].…”

Section: Discussionmentioning

confidence: 99%

Recommendations for the management of MPS IVA: systematic evidence- and consensus-based guidance

Akyol

Alden

Amartino

et al. 2019

Orphanet J Rare Dis

117

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Introduction Mucopolysaccharidosis (MPS) IVA or Morquio A syndrome is an autosomal recessive lysosomal storage disorder (LSD) caused by deficiency of the N -acetylgalactosamine-6-sulfatase (GALNS) enzyme, which impairs lysosomal degradation of keratan sulphate and chondroitin-6-sulphate. The multiple clinical manifestations of MPS IVA present numerous challenges for management and necessitate the need for individualised treatment. Although treatment guidelines are available, the methodology used to develop this guidance has come under increased scrutiny. This programme was conducted to provide evidence-based, expert-agreed recommendations to optimise management of MPS IVA. Methods Twenty six international healthcare professionals across multiple disciplines, with expertise in managing MPS IVA, and three patient advocates formed the Steering Committee (SC) and contributed to the development of this guidance. Representatives from six Patient Advocacy Groups (PAGs) were interviewed to gain insights on patient perspectives. A modified-Delphi methodology was used to demonstrate consensus among a wider group of healthcare professionals with experience managing patients with MPS IVA and the manuscript was evaluated against the validated Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument by three independent reviewers. Results A total of 87 guidance statements were developed covering five domains: (1) general management principles; (2) recommended routine monitoring and assessments; (3) disease-modifying interventions (enzyme replacement therapy [ERT] and haematopoietic stem cell transplantation [HSCT]); (4) interventions to support respiratory and sleep disorders; (5) anaesthetics and surgical interventions (including spinal, limb, ophthalmic, cardio-thoracic and ear-nose-throat [ENT] surgeries). Consensus was reached on all statements after two rounds of voting. The overall guideline AGREE II assessment score obtained for the development of the guidance was 5.3/7 (where 1 represents the lowest quality and 7 represents the highest quality of guidance). Conclusion This manuscript provides evidence- and consensus-based recommendations for the management of patients with MPS IVA and is for use by healthcare professionals that manage the holistic care of patients with the intention to improve clinical- and patient-reported outcomes and enhance patient quality of life. It is recognised that the guidance provided represents a point in time and further research is required to address current knowledge and evidence gaps. Electronic supplementary material The online version of this article (10.1186/s13023-019-1074-9) contains supplementary material, which is available to authorized users.

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Fluorimetric assays for N-acetylgalactosamine-6-sulfatase and arylsulfatase B based on the natural substrates for confirmation of mucopolysaccharidoses types IVA and VI

Cited by 13 publications

References 6 publications

Rapid and Modular Assembly of Click Substrates To Assay Enzyme Activity in the Newborn Screening of Lysosomal Storage Disorders

Rapid and Modular Assembly of Click Substrates To Assay Enzyme Activity in the Newborn Screening of Lysosomal Storage Disorders

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

Recommendations for the management of MPS IVA: systematic evidence- and consensus-based guidance

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