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

Area of Science:

• Biochemistry
• Genetics
• Mass Spectrometry

Background:

• X-linked adrenoleukodystrophy (X-ALD) is a genetic disorder caused by ABCD1 gene variants.
• ALDP protein deficiency leads to elevated C26:0-lysophosphatidylcholine (C26:0-LPC), a key biomarker.
• Current newborn screening (NBS) relies on C26:0-LPC detection for early X-ALD identification.

Purpose of the Study:

• To develop and validate a rapid, accurate method for measuring C26:0-LPC in newborn screening specimens.
• To establish reliable cutoff values for identifying newborns at risk of X-ALD.
• To improve the efficiency of X-ALD newborn screening.

Main Methods:

• Utilized flow injection analysis (FIA) coupled with electrospray ionization tandem mass spectrometry (ESI-MS/MS).
• Measured C26:0-LPC levels in dried blood spot (DBS) specimens using negative ion mode.
• Validated the method for linearity, accuracy, and precision, analyzing 5881 residual NBS specimens.

Main Results:

• The FIA-MS/MS method demonstrated high accuracy and precision for C26:0-LPC quantification.
• Established cutoff values: 0.15–0.22 µM for borderline and ≥0.23 µM for presumptive positive.
• Achieved a short analysis run-time of 1.7 minutes per sample, reducing screening time.

Conclusions:

• The presented FIA-MS/MS method is a validated, efficient tool for newborn screening of X-ALD.
• Negative mode MS effectively minimizes isobaric interferences, enhancing screening specificity.
• This method enables timely identification of infants requiring further evaluation for X-ALD.