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Abstract: SA-PO938

GalD: An Available and High-Performing Lectin-Based Test for Serum Galactose-Deficient IgA1

Session Information

Category: Glomerular Diseases

  • 1402 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Szul, Tomasz, Reliant Glycosciences, LLC, Birmingham, Alabama, United States
  • Tucholski, Janusz, Reliant Glycosciences, LLC, Birmingham, Alabama, United States
  • Street, Tatum, Reliant Glycosciences, LLC, Birmingham, Alabama, United States
  • Julian, Bruce A., Reliant Glycosciences, LLC, Birmingham, Alabama, United States
  • Placzek, Will, Reliant Glycosciences, LLC, Birmingham, Alabama, United States
Background

Quantitative lectin-based assay for serum galactose-deficient immunoglobin A1 (Gd-IgA1) has been established as leading biomarker for kidney outcomes of patients with IgA nephropathy (IgAN) since 2007. This Gd-IgA1 analysis has been included in multiple landmark papers and been used as the quantitative phenotypic basis for genome-wide association studies of IgAN and serum Gd-IgA1. Initially, the lectin-based Gd-IgA1 analysis was not amenable for broad use due to lack of scalability, long sample-analysis timeframe, and user-to-user variation. Here, we report our development of the GalD biomarker test, a highly reproducible, fast, and newly available lectin-based assay for Gd-IgA1.

Methods

We used a 24-serum-sample quality-control set that spans the Gd-IgA1 concentrations reported in the literature in a 5-hour detection protocol to perform standard validation analysis. This approach included intra- and inter-assay performance and serial measurements to assess serum freeze-thaw stability. Additionally, multiple batches of key reagents were evaluated over time to ensure assay consistency.

Results

Our validation analysis demonstrated high-quality assay performance, with less than 10% plate-to-plate error. Furthermore, the assay demonstrated six-month stability of the components. The entire range of the calibrated assay was 29-2000 ng/mL. The lower limit of detection was determined to be 0.425 ng/mL. The lower limit of quantitation was 29 ng/mL. The GalD test is fully scalable to enable testing across multiple sample plates, dates, or users, and with same-day readout.

Conclusion

Our GalD test now brings the ability to measure serum Gd-IgA1 concentration to any laboratory while assessing the full spectrum of galactose-deficient IgA1 present in serum samples.

Funding

  • NIDDK Support