Sulfatide Analysis by Mass Spectrometry for Screening of Metachromatic Leukodystrophy in Dried Blood and Urine Samples.
Sulfatide Analysis by Mass Spectrometry for Screening of Metachromatic Leukodystrophy in Dried Blood and Urine Samples.
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DOI：
10.1373/clinchem.2015.245159
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发表时间：
2016-01
影响因子：
9.3
通讯作者：
Gelb MH
中科院分区：
文献类型：
--
作者：
Spacil Z;Babu Kumar A;Liao HC;Auray-Blais C;Stark S;Suhr TR;Scott CR;Turecek F;Gelb MH
异染性脑白质营养不良（MLD）是一种由芳基硫酸酯酶A活性缺乏引起的常染色体隐性遗传疾病，导致硫苷脂底物积累。诊断和监测程序包括外周血白细胞中芳基硫酸酯酶A活性降低的证明或尿液中硫苷脂的检测。然而，筛查测试的发展是具有挑战性的，因为干血斑（DBS）中的酶不稳定，假缺陷等位基因的广泛发生，以及缺乏来自新生儿筛查项目的可用尿样。我们用LC-MS/MS测量了MLD患者DBS和干尿斑（DUS）中的单个硫苷脂谱，以确定具有区分能力的标记物，从而区分受影响的个体和对照。我们还开发了一种方法，将所有的硫苷脂分子物种转化为一个单一的物种，允许在衍生化后的正离子模式的定量。在MLD患者的DBS中，我们发现早发型和晚发型MLD的总硫苷脂浓度分别比对照组和假性缺陷组高23.2倍和5.1倍。相应的DUS显示，与对照组相比，早发和迟发MLD患者样本的差异高达164倍和78倍。使用转化为单一物质的硫苷脂简化了分析，并提高了正离子模式下的检测灵敏度，为硫苷脂分析提供了第二种选择。DBS和DUS中的硫苷脂的这项研究表明了质谱法用于新生儿MLD筛查的可行性，并为更大规模的新生儿筛查试点研究奠定了基础。
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. 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. 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. 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.