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Kidney Week

Abstract: FR-PO668

Using Degree of Foot Process Effacement to Predict Outcome in Paediatric Steroid-Resistant Nephrotic Syndrome: A Multi-Centre Analysis

Session Information

  • Pediatric Nephrology - II
    November 03, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

  • 1900 Pediatric Nephrology

Authors

  • Saleem, Moin, University of Bristol Medical School, Bristol, United Kingdom
  • Rogers, Miranda, University of Bristol Medical School, Bristol, United Kingdom
  • Mason, Anna Elizabeth, Department of Histopathology, Royal Devon and Exeter Hospitals, Exeter, United Kingdom
  • Hayward, Samantha JL, University of Bristol Medical School, Bristol, United Kingdom
  • Colby, Liz, University of Bristol Medical School, Bristol, United Kingdom
  • Welsh, Gavin Iain, University of Bristol Medical School, Bristol, United Kingdom
  • Ding, Wen Yi, University of Bristol Medical School, Bristol, United Kingdom
Background

Steroid resistant nephrotic syndrome (SRNS) is a common cause of paediatric end-stage renal failure requiring transplantation. Recurrence post-transplantation is high in those with no identified pathogenic variant, but those with pathogenic mutations rarely develop recurrence post-transplantation. Previous work suggests that degree of native renal biopsy podocyte foot process effacement (FPE) may distinguish genetic and non-genetic causes of SRNS, but the studies are limited by small samples and single-centre recruitment. This suggests that degree of native biopsy FPE may detect risk of post-transplant recurrence. We hypothesised that diffuse FPE is a marker of circulating factor disease and predicts post-transplant recurrence, while segmental FPE is a marker of non-recurrent disease.

Methods

We analysed a multi-centre nationwide cohort of paediatric SRNS patients (RADAR) to assess if FPE degree can predict disease recurrence. 138 paediatric Nephrotic Syndrome patients had transplantation between 2007-22. 28 with native biopsy electron microscopy (EM) reports available were included. We quantified FPE as diffuse or segmental from report language.

Results

9/28 patients developed disease recurrence. 27 patients had genetic testing, of which 11 had a causative genetic mutation. No patients with pathogenic genetic variants developed recurrence (recurrence if pathogenic variant 0/11; recurrence if no pathogenic variant 9/17, p=0.0039). 9/11 patients with pathogenic variants show diffuse FPE on EM while 9/17 without identified genetic mutations show diffuse FPE (p=0.2264). All 7 patients with slit diaphragm protein pathogenic mutations had diffuse FPE. Patients with diffuse FPE (recurrence 4/18) trended towards lower recurrence rates than those with segmental FPE (recurrence 5/10, p=0.2096).

Conclusion

In this multi-centre cohort we show trends between genetic causes of SRNS and FPE, and the direction of the association contrasts with literature. We show that slit diaphragm protein mutations are associated with diffuse FPE. We show a not statistically significant trend towards diffuse FPE and lower recurrence post-transplant. This study is limited by small numbers and its retrospective nature, but the trends justify further investigation in larger groups of patients.