Newborn Screen for X-Linked Adrenoleukodystrophy Using Flow Injection Tandem Mass Spectrometry in Negative Ion Mode

Tarek A Teber; Brian J Conti; Christopher A Haynes; Amy Hietala; Mei W Baker

doi:10.3390/ijns8020027

Newborn Screen for X-Linked Adrenoleukodystrophy Using Flow Injection Tandem Mass Spectrometry in Negative Ion Mode

Int J Neonatal Screen. 2022 Apr 14;8(2):27. doi: 10.3390/ijns8020027.

Authors

Tarek A Teber¹, Brian J Conti¹, Christopher A Haynes², Amy Hietala³, Mei W Baker^{1

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Affiliations

¹ Newborn Screening Laboratory, Wisconsin State Laboratory of Hygiene, University of Wisconsin School of Medicine and Public Health, 465 Henry Mall, Madison, WI 53706, USA.
² Newborn Screening and Molecular Biology Branch, Centers for Disease Control and Prevention, 4770 Buford Hwy. NE, Atlanta, GA 30341, USA.
³ Newborn Screening Laboratory, Minnesota Department of Health, St. Paul, MN 55164, USA.
⁴ Genetics and Metabolism Division, Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, 1500 Highland Avenue, Madison, WI 53705, USA.
⁵ Center for Human Genomics and Precision Medicine, University of Wisconsin School of Medicine and Public Health, Madison, 1111 Highland Avenue, Madison, WI 53705, USA.

Abstract

X-linked adrenoleukodystrophy (X-ALD) is a genetic disorder caused by pathogenic variants in the ATP-binding cassette subfamily D member 1 gene (ABCD1) that encodes the adrenoleukodystrophy protein (ALDP). Defects in ALDP result in elevated cerotic acid, and lead to C26:0-lysophosphatidylcholine (C26:0-LPC) accumulation, which is the primary biomarker used in newborn screening (NBS) for X-ALD. C26:0-LPC levels were measured in dried blood spot (DBS) NBS specimens using a flow injection analysis (FIA) coupled with electrospray ionization (ESI) tandem mass spectrometry (MS/MS) performed in negative ion mode. The method was validated by assessing and confirming linearity, accuracy, and precision. We have also established C26:0-LPC cutoff values that identify newborns at risk for X-ALD. The mean concentration of C26:0-LPC in 5881 de-identified residual routine NBS specimens was 0.07 ± 0.02 µM (mean + 1 standard deviation (SD)). All tested true X-ALD positive and negative samples were correctly identified based on C26:0-LPC cutoff concentrations for borderline between 0.15 µM and 0.22 µM (mean + 4 SD) and presumptive screening positive at ≥0.23 µM (mean + 8 SD). The presented FIA method shortens analysis run-time to 1.7 min, while maintaining the previously established advantage of utilizing negative mode MS to eliminate isobaric interferences that could lead to screening false positives.

Keywords: C26:0-lysophosphatidylcholine; X-linked adrenoleukodystrophy; dried blood spots; flow injection analysis; newborn screening; tandem mass spectrometry.