Abstract: TH-PO003

Presentations, Outcomes, and Complement Gene Analysis in a Single-Center Cohort of Patients with Atypical Hemolytic Uremic Syndrome

Session Information

Category: Genetic Diseases of the Kidney

  • 803 Genetic Epidemiology and Other Genetic Studies of Common Kidney Diseases

Authors

  • Bobba, Sindhura, Virginia Commonwealth University, Richmond, Virginia, United States
  • Kidd, Jason M., Virginia Commonwealth University, Richmond, Virginia, United States
  • Carl, Daniel E., Virginia Commonwealth University, Richmond, Virginia, United States
  • Kumar, Dhiren, Virginia Commonwealth University, Richmond, Virginia, United States
  • King, Anne L, Virginia Commonwealth University, Richmond, Virginia, United States
  • Gupta, Gaurav, Virginia Commonwealth University, Richmond, Virginia, United States
Background

Previous data suggests that up to 50% of patients with atypical hemolytic uremic syndrome (aHUS) might not have detectable complement gene mutations. In this single-center analysis of the aHUS registry we report our experience on 15 consecutive patients with aHUS.

Methods

Patients were enrolled between 2012-2017 at variable time points after initial presentation. The exonic regions of 12 genes including Complement Factor FH (CFH), MCP (CD46), CFI, C3, CFB, CFHR1, CFHR3, CFHR4, CFHR5, Thrombomodulin, Plasminogen and DGKE were analyzed using commercially available testing.

Results

The mean age at diagnosis was 42±18 years. A majority were females (10/15; 67%) and 40% (6/15) were African-Americans. Seven (47%) presented with thrombotic microangiopathy (TMA) and renal failure, of these 4 (out of 7; 57%) recovered kidney function with C5 blockade therapy (eculizumab). Only one patient did not respond to eculizumab therapy and progressed to end-stage renal disease (ESRD). Of the remaining eight, 6 (40%) were diagnosed in the setting of a pre-transplant evaluation or allograft failure. Of these six, 3 (50%) got transplanted. Two patients (13%) were diagnosed with aHUS post-transplant. All 5 patients with kidney transplants have been maintained on indefinite eculizumab and have intact graft function at a median follow-up of 2.5 years (range1-3 years). Genetic analysis of these 15 patients revealed 39 mutations. A majority of patients (13/15; 87%) were noted to harbor complement mutations with seven (47%) having mutations in more than one gene. CFH mutations and Complement Factor H-related protein (CFHR3- CHFR1) deletions were the most frequent (8 patients each; 61%). Three patients (20%) had MCP/CD46 mutations (IVS9-78 G>A). Patients with homozygous mutations had a trend towards presentation at a younger age (mean 35 vs 50 years; p=0.1) compared with those with heterozygous mutations.

Conclusion

In this single-center analysis of 15 consecutive aHUS patients, we report that a large majority (87%) had complement gene mutations. This might represent increasing knowledge of identifiable mutations in the contemporary era. A large majority of patients had an excellent response to C5 blockade. Patients being evaluated for kidney transplants with a history of unexplained TMA should be screened for aHUS.