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Kidney Week

Abstract: SA-PO770

Benefits of Genetic Testing in Patients with Polycystic Kidney Disease (PKD)

Session Information

Category: Genetic Diseases of the Kidneys

  • 1201 Genetic Diseases of the Kidneys: Cystic

Authors

  • Samuels, Marissa R., Thomas Jefferson University, Philadelphia, Pennsylvania, United States
  • Zeng, Wing H., Thomas Jefferson University, Philadelphia, Pennsylvania, United States
  • Zhang, JingJing, Thomas Jefferson University, Philadelphia, Pennsylvania, United States
Background

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common inherited kidney disease, responsible for ~10% of end stage renal disease. The most common mutated genes are PKD1 or PKD2 and ~90% of patients have an identifiable genetic variant within the two. While genetic testing has identified these mutations and their predictive values, the specific clinical significance is still not well defined. Additionally, comprehensive screenings have successfully identified PKD1 and PKD2s roles in ADPKD, but there are still patients who have no mutation detected in either gene.

Methods

Data recorded by electronic medical record of patients with image diagnosed PKD at a single nephrology clinic was collected and analyzed. Natera Genetic testing results identified genetic variants. Family history (FH) was used to determine genetic predisposition.

Results

Forty patients with PKD were identified between December 2020 and December 2022. Twenty Seven were positive for a PKD1/PKD2 mutation, 7 of which had a variant of uncertain significance (VUS) of PKD1/PKD2. Seventeen of these 27 had a positive FH of PKD, while 8 were negative and 1 unknown. Three patients did not have a PKD1/PKD2 mutation, but tested positive for mutations COL4A1, COL4A4 and TTC21B. Lastly, there were 3 patients with negative results, one of which has a FH.

Conclusion

Eighty Five percent of the patients in our cohort have a PKD1/PKD2 mutation or PKD1/PKD2 VUS, with some VUSs becoming pathogenic at a later time. However, 30% of those patients do not have a FH. The genetic study thus confirmed the diagnosis and helped predict their prognosis. The existence of heterozygous PKHD1 together with Col4A4 mutation may be the culprit of the kidney cysts in patients with Alport syndrome.The patients with true negative results remain unclear, but the sequence data will contribute to the nationwide database and help identify the true variants. Our experience advocates that the benefit of genetic testing is imperative to detecting and identifying true causative variants and that this can provide prognostic information for patients with ADPKD.