Dataset Information

Sulfatide Analysis by Mass Spectrometry for Screening of Metachromatic Leukodystrophy in Dried Blood and Urine Samples.

ABSTRACT: BACKGROUND:Metachromatic leukodystrophy (MLD) is an autosomal recessive disorder caused by deficiency in arylsulfatase A activity, leading to accumulation of sulfatide substrates. Diagnostic and monitoring procedures include demonstration of reduced arylsulfatase A activity in peripheral blood leukocytes or detection of sulfatides in urine. However, the development of a screening test is challenging because of instability of the enzyme in dried blood spots (DBS), the widespread occurrence of pseudodeficiency alleles, and the lack of available urine samples from newborn screening programs. METHODS:We measured individual sulfatide profiles in DBS and dried urine spots (DUS) from MLD patients with LC-MS/MS to identify markers with the discriminatory power to differentiate affected individuals from controls. We also developed a method for converting all sulfatide molecular species into a single species, allowing quantification in positive-ion mode upon derivatization. RESULTS:In DBS from MLD patients, we found up to 23.2-fold and 5.1-fold differences in total sulfatide concentrations for early- and late-onset MLD, respectively, compared with controls and pseudodeficiencies. Corresponding DUS revealed up to 164-fold and 78-fold differences for early- and late-onset MLD patient samples compared with controls. The use of sulfatides converted to a single species simplified the analysis and increased detection sensitivity in positive-ion mode, providing a second option for sulfatide analysis. CONCLUSIONS:This study of sulfatides in DBS and DUS suggests the feasibility of the mass spectrometry method for newborn screening of MLD and sets the stage for a larger-scale newborn screening pilot study.

SUBMITTER: Spacil Z

PROVIDER: S-EPMC4737087 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature

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Sulfatide Analysis by Mass Spectrometry for Screening of Metachromatic Leukodystrophy in Dried Blood and Urine Samples.

Spacil Zdenek Z Babu Kumar Arun A Liao Hsuan-Chieh HC Auray-Blais Christiane C Stark Samantha S Suhr Teryn R TR Scott C Ronald CR Turecek Frantisek F Gelb Michael H MH

Clinical chemistry 20151119 1

<h4>Background</h4>Metachromatic leukodystrophy (MLD) is an autosomal recessive disorder caused by deficiency in arylsulfatase A activity, leading to accumulation of sulfatide substrates. Diagnostic and monitoring procedures include demonstration of reduced arylsulfatase A activity in peripheral blood leukocytes or detection of sulfatides in urine. However, the development of a screening test is challenging because of instability of the enzyme in dried blood spots (DBS), the widespread occurrenc ...[more]

PMID: 26585924

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Project description:We aimed to gain more insight into the pathomechanisms of metachromatic leukodystrophy (MLD), by comparing magnitude and direction of diffusion between patients and controls at diagnosis and during follow-up.Four late-infantile, 16 juvenile and 8 adult onset MLD patients [of which 13 considered eligible for hematopoietic cell transplantation (HCT)] and 47 controls were examined using diffusion tensor imaging. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) were quantified and compared between groups using tract-based spatial statistics (TBSS). Diffusion measures were determined for normal-appearing white matter (NAWM), corpus callosum, thalamus (all based on subject-wise segmentation), and pyramidal tracts, determined with probabilistic tractography. Measures were compared between HCT-eligible patients, non-eligible patients and controls using general linear model and nonparametric permutation analyses (randomise) for TBSS data, considering family-wise error corrected p < 0.05 significant.Throughout white matter (WM), FA was decreased and MD and RD increased in both patient groups compared to controls, while AD was decreased in NAWM and corpus callosum. In the thalamus, no differences in FA were observed, but all diffusivities were increased in both patient groups. Differences were most pronounced between controls and patients non-eligible for HCT. Longitudinally (median follow-up 3.9 years), diffusion measures remained relatively stable for HCT-treated patients, but were progressively abnormal for non-eligible patients.The observed diffusion measures confirm that brain microstructure is changed in MLD, reflecting different pathological processes including loss of myelin and sulfatide accumulation. The observation of both increased and decreased AD probably reflects a balance between myelin and axonal loss vs. intracellular sulfatide storage in macrophages, depending on region and disease stage.

Project description:Metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal disorder caused by the deficiency of arylsulfatase A (ASA), resulting in impaired degradation of sulfatide, an essential sphingolipid of myelin. The clinical manifestations of MLD are characterized by progressive demyelination and subsequent neurological symptoms resulting in severe debilitation. The availability of therapeutic options for treating MLD is limited but expanding with a number of early stage clinical trials already in progress. In the development of therapeutic approaches for MLD, scientists have been facing a number of challenges including blood-brain barrier (BBB) penetration, safety issues concerning therapies targeting the central nervous system, uncertainty regarding the ideal timing for intervention in the disease course, and the lack of more in-depth understanding of the molecular pathogenesis of MLD. Here, we discuss the current status of the different approaches to developing therapies for MLD. Hematopoietic stem cell transplantation has been used to treat MLD patients, utilizing both umbilical cord blood and bone marrow sources. Intrathecal enzyme replacement therapy and gene therapies, administered locally into the brain or by generating genetically modified hematopoietic stem cells, are emerging as novel strategies. In pre-clinical studies, different cell delivery systems including microencapsulated cells or selectively neural cells have shown encouraging results. Small molecules that are more likely to cross the BBB can be used as enzyme enhancers of diverse ASA mutants, either as pharmacological chaperones, or proteostasis regulators. Specific small molecules may also be used to reduce the biosynthesis of sulfatides, or target different affected downstream pathways secondary to the primary ASA deficiency. Given the progressive neurodegenerative aspects of MLD, also seen in other lysosomal diseases, current and future therapeutic strategies will be complementary, whether used in combination or separately at specific stages of the disease course, to produce better outcomes for patients afflicted with this devastating inherited disorder.

Dataset Information

Sulfatide Analysis by Mass Spectrometry for Screening of Metachromatic Leukodystrophy in Dried Blood and Urine Samples.

Publications

Sulfatide Analysis by Mass Spectrometry for Screening of Metachromatic Leukodystrophy in Dried Blood and Urine Samples.

Similar Datasets

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