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Kidney Week

Abstract: FR-PO783

Mutations in UMOD Are Associated with FSGS and Can Be Mistaken for a Glomerular Disease

Session Information

Category: Genetic Diseases of the Kidneys

  • 1002 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Chun, Justin, University of Calgary, Calgary, Alberta, Canada
  • Wang, Minxian, Broad Institute, Cambridge, Massachusetts, United States
  • Bu, Lihong, University of Minnesota, Minneapolis, Minnesota, United States
  • Pollak, Martin R., Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, United States
Background

Focal segmental glomerulosclerosis (FSGS) is a common histopathologically defined kidney lesion that can be observed with various underlying causes, including highly penetrant gene mutations. We recently identified pathogenic variants of UMOD, a gene encoding the tubular protein uromodulin, in seven families with suspected or biopsy proven FSGS.

Methods

We reviewed the clinical and pathology reports of seven families identified to have pathogenic variants of UMOD. Sanger sequencing of affected and unaffected to verify co-segregation with disease.

Results

Review of clinical records and pathology reports confirmed biopsy-proven cases of FSGS in 33% of patients with UMOD variants. The UMOD variants seen in these families were mutations previously reported in association with uromodulin associated kidney disease (UAKD). Consistent with the features for UAKD, most patients in our study presented with autosomal dominant inheritance, subnephrotic range proteinuria, minimal hematuria, and renal impairment. These patients with UMOD associated kidney disease did not have the classic clinical characteristics of gout, hyperuricemia, or presence of renal cysts on renal ultrasound. Kidney biopsies showed histologic features of glomerular injury consistent with secondary FSGS including focal sclerosis and podocyte foot process effacement.

Conclusion

Our study demonstrates that using our standard clinical testing using a kidney biopsy, patients with UAKD can be mistaken for FSGS since there are no specific histopathological features for UAKD. Genetic testing can clarify the diagnosis of UAKD with secondary FSGS. Genetic testing should be considered for families diagnosed as familial FSGS or hereditary glomerulonephritis of unclear etiology.

Funding

  • NIDDK Support