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Kidney Week

Abstract: PO1297

Utilization of Broad-Panel Genetic Testing for Collagen Disorders of the Basement Membrane Disorders in Patients Requiring Kidney Transplantation

Session Information

Category: Genetic Diseases of the Kidneys

  • 1002 Genetic Diseases of the Kidneys: Non-Cystic

Authors

  • Sodhi, Rupi K., Loyola University Medical Center, Maywood, Illinois, United States
  • Desai, Amishi S., Loyola University Medical Center, Maywood, Illinois, United States
  • Yoo, Jongwon, Loyola University Medical Center, Maywood, Illinois, United States
  • Arwindekar, Divya Jain, Loyola University Medical Center, Maywood, Illinois, United States
  • Brossart, Katya, Natera, Inc., San Carlos, California, United States
  • Tabriziani, Hossein, Natera, Inc., San Carlos, California, United States
  • Akkina, Sanjeev, Loyola University Medical Center, Maywood, Illinois, United States
Background

Patients with advanced chronic kidney disease (CKD) are often misdiagnosed. Etiology of end-stage kidney disease (ESKD) significantly impacts the selection of candidates and donors for kidney transplant (KT), and post-KT management. Identification of a genetic etiology can reclassify disease and alter KT planning. Collagen disorders such as Alport syndrome present with heterogeneous phenotypes. However, a recently proposed classification system incorporates genetic variants into the diagnosis of this disease.

Methods

Twenty-two pre- and post-KT patients with a median age of 33 years (range: 26-67 years), completed genetic testing with RenasightTM (a NGS-based >380-gene kidney panel), between June 2020 and April 2021. Test results related to COL4A were correlated to clinical histories, including biopsy (when available), ultrasound results, presence of proteinuria and hematuria, demographic factors, family history and comorbidities. Certified genetic counselors interpreted the results and provided consultation to patients on request.

Results

Pathogenic or likely pathogenic variants in a type IV collagen gene were identified in 18.2% (4/22) of patients. All four patients had progressed to ESKD at the time of testing. One patient, with a variant in COL4A3, had a right nephrectomy and subsequently developed nephrotic range proteinuria. The second patient, with a variant in COL4A4, had genetic testing after a living related KT; the donor was subsequently referred for genetic counseling. The third and fourth individuals, brothers with a family history of CKD, for which the same familial COL4A5 variant was identified, were both carriers of the APOL1 G1 risk allele. One brother had biopsy-proven FSGS and did not respond to steroids.

Conclusion

Broad panel testing enables the identification of monogenic causes of CKD that can impact the selection of KT candidates and post-KT management. In this study, molecular diagnosis and genetic subtyping of type IV collagen disorders allowed providers to counsel patients on risk of disease recurrence and donor screening in potential living related donors. KT recipients with causal COL4A3/4/5 variants have a low risk of recurrence in the allograft and will likely not require extensive therapy during after transplant.