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Abstract: TH-PO511

Idiopathic Nodular Glomerulosclerosis Associated With APOL1 Mutation

Session Information

Category: Glomerular Diseases

  • 1303 Glomerular Diseases: Clinical‚ Outcomes‚ and Trials

Authors

  • Zonoozi, Shahrzad, The George Washington University, Washington, District of Columbia, United States
  • Shankaranarayanan, Divya, The George Washington University, Washington, District of Columbia, United States
  • Tariq, Anam, The George Washington University, Washington, District of Columbia, United States
  • Raj, Dominic S., The George Washington University, Washington, District of Columbia, United States
Introduction

Idiopathic nodular glomerulosclerosis (ING) is a pathologic diagnosis with features indistinguishable from diabetic nodular glomerulosclerosis in the absence of abnormal glucose metabolism. ING has been associated with hypertension (HTN), smoking and obesity. We present a case of ING in a non-smoker.

Case Description

A 58-year-old African American male non-smoker with HTN and obesity presented for evaluation of 5-6 months of leg edema and uncontrolled HTN. Evaluation revealed anemia, thrombocytopenia, creatinine (Cr) 2.7mg/dL, albumin 2.6g/dL and hemoglobin A1c 5.5%. Serologic work up was negative. Random urine protein/Cr ratio was 13.4g/g Cr and so patient underwent a kidney biopsy.

Biopsy demonstrated 1/10 globally sclerotic glomeruli with nodular expansion and mild-moderate mesangial hypercellularity. Glomerular basement membrane was thickened. Interstitial fibrosis and tubular atrophy affected 60-70% of cortex with marked interstitial inflammatory infiltrate. Electron microscopy showed extensive podocyte foot process effacement. Immunofluorescence showed glomeruli with trace granular peripheral capillary wall staining with IgM, C1q and C3. Overall, findings suggestive of nodular glomerulosclerosis, chronic thrombotic microangiopathy (TMA), chronic active interstitial nephritis and moderate arteriosclerosis.

Additionally, the patient underwent genetic evaluation, which revealed 2 risk alleles in the APOL1 gene (G1 and G2) as well as carrier status for SLC6A19 and a variant of unknown significance in NPHS1.

Discussion

Our patient presented with nephrotic syndrome and was found to have ING and TMA on biopsy. Although ING has been linked to HTN and smoking, our patient was a non-smoker, whose workup revealed risk alleles in the APOL1 gene. As far as we are aware this is the first report of an association between ING and the APOL1 gene.

Figure 1. Light microscopy showing nodular glomerulosclerosis