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Abstract: FR-PO1127

APOL1 Risk Alleles Are Critical for the Development of Collapsing Glomerulopathy in Brazilian Children

Session Information

Category: Glomerular Diseases

  • 1203 Glomerular Diseases: Clinical, Outcomes, and Trials

Authors

  • Watanabe, Andreia, University of Sao Paulo, Sao Paulo, Brazil
  • Neves, Precil D., University of Sao Paulo, Sao Paulo, Brazil
  • Watanabe, Elieser H., University of Sao Paulo, Sao Paulo, Brazil
  • Lerario, Antonio Marcondes, University of Michigan, Ann Arbor, Michigan, United States
  • Padovan, Fabiola L., University of Sao Paulo, Sao Paulo, Brazil
  • Narcizo, Amanda M., University of Sao Paulo, Sao Paulo, Brazil
  • Hildebrandt, Friedhelm, Boston Children's Hospital, Boston, Massachusetts, United States
  • Sampson, Matt G., University of Michigan, Ann Arbor, Michigan, United States
  • Onuchic, Luiz F., University of Sao Paulo, Sao Paulo, Brazil
Background

Collapsing glomerulopathy (CG) is associated with worse renal outcome than any FSGS histologic variant, while APOL1 risk alleles are associated with FSGS and increased susceptibility to CG. In pediatric population, such alleles are related to later FSGS presentation, worse eGFR and faster progression to ESKD.

Methods

A retrospective analysis of 41 children with steroid-resistant nephrotic syndrome (SRNS) or congenital NS (CNS) with onset at 2 months-16 years was performed. All had biopsies analyzed by renal pathologists. Mutational analysis in 42 genes related to glomerular diseases was performed using a capture-based, customized panel followed by NGS using an Illumina MiSeq V2.

Results

CG was diagnosed in 10/41 patients, all negative for HIV, hepatitis B and C and CMV. Of these 10, 5 were Caucasian (C) and 5 mixed race (MR); all self-reported. Five CG children were treated with prednisone plus FK506/CyA/MMF and 2 with methylprednisolone boluses (renal failure at presentation). Two with CNS were given no immunosuppression. 8/10 CG patients reached ESKD within 0.0-3.8 years after initial manifestation. The other 2 have eGFR of 88 and 60 mL/min/1.73m2, after 4 and 5 years of follow-up, respectively. A high-risk (HR) APOL1 genotype was detected in 5/10 CG patients, 2 C and 3 MR. 2/5 were extreme preterm; the other 3 had birth weight <3 kg. Of the remaining 5 with CG, 2/5 had 1 APOL1 risk allele (1 C and 1 MR), 1 was homozygous for a novel likely pathogenic variant in PLCE1 (p.L1233P), and 1 was heterozygous for a rare, frameshift variant in LAMB2. Of the 31 without CG, 4 had a single APOL1 risk allele and 27 none. Overall, Brazilian children with CG had significantly higher odds of harboring a HR APOL1 genotype (OR=∞, CI:6.6,∞: p=0.0003).

Conclusion

For Brazilian children with SRNS/CNS, as compared to other histologic diagnoses, those with CG have greatly increased odds of having a HR APOL1 genotype. Furthermore, the burden of APOL1-associated SRNS/CNS spanned self-described races. Finally, all with CG and HR APOL1 genotype had an abnormal birth history. The discovered racial, histologic, and birth history correlates of a HR APOL1 genotype have important implications for future APOL1 genotyping efforts in research and clinical settings in Brazil.

Funding

  • Private Foundation Support