Measurement of psychosine in dried blood spots: a potential improvement of newborn screening for Krabbe disease

Abstract Background: Newborn screening for deficiency in the lysosomal enzymes that cause Fabry, Gaucher, Krabbe, Niemann–Pick A/B, and Pompe diseases is warranted because treatment for these syndromes is now available or anticipated in the near feature. We describe a multiplex screening method for all five lysosomal enzymes that uses newborn-screening cards containing dried blood spots as the enzyme source. Methods: We used a cassette of substrates and internal standards to directly quantify the enzymatic activities, and tandem mass spectrometry for enzymatic product detection. Rehydrated dried blood spots were incubated with the enzyme substrates. We used liquid-liquid extraction followed by solid-phase extraction with silica gel to remove buffer components. Acarbose served as inhibitor of an interfering acid α-glucosidase present in neutrophils, which allowed the lysosomal enzyme implicated in Pompe disease to be selectively analyzed. Results: We analyzed dried blood spots from 5 patients with Gaucher, 5 with Niemann–Pick A/B, 11 with Pompe, 5 with Fabry, and 12 with Krabbe disease, and in all cases the enzyme activities were below the minimum activities measured in a collection of heterozygous carriers and healthy noncarrier individuals. The enzyme activities measured in 5–9 heterozygous carriers were approximately one-half those measured with 15–32 healthy individuals, but there was partial overlap of each condition between the data sets for carriers and healthy individuals. Conclusion: For all five diseases, the affected individuals were detected. The assay can be readily automated, and the anticipated reagent and supply costs are well within the budget limits of newborn-screening centers.

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Utility of measuring very long-chain fatty-acyl carnitines in dried blood spots for newborn screening of X-linked Adrenoleukodystrophy

Molecular Genetics and Metabolism Reports ◽

10.1016/j.ymgmr.2021.100720 ◽

2021 ◽

Vol 26 ◽

pp. 100720

Author(s):

Archana Natarajan ◽

Rita Christopher ◽

Shruti V. Palakuzhiyil ◽

Sadanandavalli Retnaswami Chandra

Keyword(s):

Newborn Screening ◽

Dried Blood Spots ◽

Fatty Acyl ◽

Blood Spots ◽

Long Chain

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Concurrent Confirmation and Differential Diagnosis of Congenital Adrenal Hyperplasia from Dried Blood Spots: Application of a Second-Tier LC-MS/MS Assay in a Cross-Border Cooperation for Newborn Screening

Hormone Research in Paediatrics ◽

10.1159/000439380 ◽

2015 ◽

Vol 84 (5) ◽

pp. 311-318 ◽

Cited By ~ 9

Author(s):

Péter Monostori ◽

Pál Szabó ◽

Otilia Marginean ◽

Csaba Bereczki ◽

Eszter Karg

Keyword(s):

Differential Diagnosis ◽

Congenital Adrenal Hyperplasia ◽

Newborn Screening ◽

Dried Blood Spots ◽

Adrenal Hyperplasia ◽

Blood Spots ◽

Cross Border ◽

Second Tier ◽

Cross Border Cooperation

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Newborn screening for severe combined immunodeficiency: Evaluation of a commercial T-cell receptor excision circle-based method in Victorian dried blood spots

Journal of Paediatrics and Child Health ◽

10.1111/jpc.13659 ◽

2017 ◽

Vol 54 (1) ◽

pp. 14-19 ◽

Cited By ~ 3

Author(s):

Stephanie Richards ◽

James Pitt ◽

Sharon Choo

Keyword(s):

T Cell ◽

Newborn Screening ◽

T Cell Receptor ◽

Severe Combined Immunodeficiency ◽

Cell Receptor ◽

Dried Blood Spots ◽

Combined Immunodeficiency ◽

Blood Spots

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Second-Tier Test for Quantification of Alloisoleucine and Branched-Chain Amino Acids in Dried Blood Spots to Improve Newborn Screening for Maple Syrup Urine Disease (MSUD)

Clinical Chemistry ◽

10.1373/clinchem.2007.098434 ◽

2008 ◽

Vol 54 (3) ◽

pp. 542-549 ◽

Cited By ~ 65

Author(s):

Devin Oglesbee ◽

Karen A Sanders ◽

Jean M Lacey ◽

Mark J Magera ◽

Bruno Casetta ◽

...

Keyword(s):

Amino Acids ◽

Newborn Screening ◽

Dried Blood Spots ◽

Branched Chain Amino Acids ◽

Maple Syrup ◽

Blood Spots ◽

Urine Disease ◽

Second Tier ◽

Branched Chain ◽

Positive Results

Abstract Background: Newborn screening for maple syrup urine disease (MSUD) relies on finding increased concentrations of the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine by tandem mass spectrometry (MS/MS). d-Alloisoleucine (allo-Ile) is the only pathognomonic marker of MSUD, but it cannot be identified by existing screening methods because it is not differentiated from isobaric amino acids. Furthermore, newborns receiving total parenteral nutrition often have increased concentrations of BCAAs. To improve the specificity of newborn screening for MSUD and to reduce the number of diet-related false-positive results, we developed a LC-MS/MS method for quantifying allo-Ile. Methods: Allo-Ile and other BCAAs were extracted from a 3/16-inch dried blood spot punch with methanol/H2O, dried under nitrogen, and reconstituted into mobile phase. Quantitative LC-MS/MS analysis of allo-Ile, its isomers, and isotopically labeled internal standards was achieved within 15 min. To determine a reference interval for BCAAs including allo-Ile, we analyzed 541 dried blood spots. We also measured allo-Ile in blinded samples from 16 MSUD patients and 21 controls and compared results to an HPLC method. Results: Intra- and interassay imprecision (mean CVs) for allo-Ile, leucine, isoleucine, and valine ranged from 1.8% to 7.4%, and recovery ranged from 91% to 129%. All 16 MSUD patients were correctly identified. Conclusions: The LC-MS/MS method can reliably measure allo-Ile in dried blood spots for the diagnosis of MSUD. Applied to newborn screening as a second-tier test, it will reduce false-positive results, which produce family anxiety and increase follow-up costs. The assay also appears suitable for use in monitoring treatment of MSUD patients.

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