Rapid, proteomic urine assay for monitoring progressive organ disease in Fabry disease

Background: Fabry disease is a progressive multisystemic disease, which affects the kidney and cardiovascular systems. Various treatments exist but decisions on how and when to treat are contentious. The current marker for monitoring treatment is plasma globotriaosylsphingosine (lyso-Gb3), but it is not informative about the underlying and developing disease pathology.

Methods: We have created a urine proteomic assay containing a panel of biomarkers designed to measure disease-related pathology which include the inflammatory system, lysosome, heart, kidney, endothelium and cardiovascular system. Using a targeted proteomic-based approach, a series of 40 proteins for organ systems affected in Fabry disease were multiplexed into a single 10 min multiple reaction monitoring Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS) assay and using only 1 mL of urine.

Results: Six urinary proteins were elevated in the early-stage/asymptomatic Fabry group compared with controls including albumin, uromodulin, α1-antitrypsin, glycogen phosphorylase brain form, endothelial protein receptor C and intracellular adhesion molecule 1. Albumin demonstrated an increase in urine and could indicate presymptomatic disease. The only protein elevated in the early-stage/asymptomatic patients that continued to increase with progressive multiorgan involvement was glycogen phosphorylase brain form. Podocalyxin, fibroblast growth factor 23, cubulin and Alpha-1-Microglobulin/Bikunin Precursor (AMBP) were elevated only in disease groups involving kidney disease. Nephrin, a podocyte-specific protein, was elevated in all symptomatic groups. Prosaposin was increased in all symptomatic groups and showed greater specificity (p<0.025-0.0002) according to disease severity.

Conclusion: This work indicates that protein biomarkers could be helpful and used in conjunction with plasma lyso-Gb3 for monitoring of therapy or disease progression in patients with Fabry disease.