Supplementary Material for: Urinary myeloid bodies as a biomarker for early diagnosis and monitoring of enzyme replacement therapy in Fabry disease

Introduction: The prevalence of urinary myeloid bodies in Fabry disease patients and their correlation with renal involvement remains unclear. Methods: This single-center, retrospective study included 25 patients with Fabry disease and 27 controls. We analyzed 24-hour urine samples for the presence of urinary myeloid bodies and evaluated clinical data, including serum creatinine, estimated glomerular filtration rate (eGFR), 24-hour urinary protein levels, α-Gal A, and Lyso-GL-3. Seven Fabry patients underwent analysis of urine samples before and after one year of enzyme replacement therapy (ERT). Results: Urinary myeloid bodies were detected in 84% of Fabry patients (21 out of 25), with no significant gender differences. None of the healthy controls or patients with other renal disease patients had urinary myeloid bodies. Among the Fabry patients with myeloid bodies, 48% had no proteinuria, and 52% were in CKD1 stage G1. Furthermore, urinary myeloid bodies were detected in four patients under the age of 20, despite the absence of or only minimal proteinuria, and these patients all exhibited a substantial number of myeloid bodies. After one year of ERT, significant reductions in both the count (P=0.043) and area ratio (P=0.028) of myeloid bodies were observed. Conclusion: Urinary myeloid bodies are specific to Fabry disease and are associated with early renal injury, even in the absence of proteinuria. These findings suggest that urinary myeloid bodies may serve as a non-invasive biomarker for the early diagnosis of Fabry disease and for monitoring the efficacy of ERT.