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Abstract: SA-PO623

Impact of High-Risk APOL1 Variants in Kidney Disease in South America

Session Information

Category: Genetic Diseases of the Kidney

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

Authors

  • Riella, Cristian, Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Siemens, Tobias August, Hospital Universitário Evangélico de Curitiba, Curitiba, Brazil
  • Campos, Rodrigo P., Federal University of Alagoas, Maceio, Alagoas, Brazil
  • Moraes, Thyago Proença de, Pontificia Universidade Catolica do Parana, Curitiba, Brazil
  • Friedman, David J., Beth Israel Deaconess Medical Center, Boston, Massachusetts, United States
  • Riella, Miguel C., Hospital Universitário Evangélico de Curitiba, Curitiba, Brazil
  • Pollak, Martin R., Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, Massachusetts, United States
Background

The presence of apolipoprotein L-1 (APOL1) mutations is associated with increased risk of end-stage renal disease (ESRD) in African Americans. This effect has not been investigated in South Americans of African descent. In this study we analyzed APOL1 variants in dialysis patients and healthy controls with African descent in Brazil.

Methods

Inclusion criteria: dialysis patients 18 years of age or older who reportedly had African ancestry, first degree relatives were selected as controls. Exclusion criteria: individuals below the age of 18, history of obstructive uropathy, polycystic kidney disease, and known SLE or other vasculitic etiologies. After informed consent was obtained, clinical data along with blood samples for DNA extraction were collected. Genotyping was performed with a TaqMan RT-PCR assay for the wild type allele G0, and G1 and G2 risk alleles.

Results

440 individuals were included in the study (271 patients and 169 controls). The frequency of high risk variants (G1,G2) was higher in dialysis patients than controls: one risk variant frequency was 17.7%(48) vs. 10.6%(18); two risk variants: 12.2%(33) vs. 1.2%(2), respectively. In a multivariate logistic regression model, the presence of one risk variant was associated with a 4-fold increase in risk of ESRD (OR=3.95, p=0.002, CI=1.68-9.27); while carriers of two risk variants had a 21-fold increase in risk of ESRD (OR=21.66, p<0.0001, 95% CI= 4.13-113.51). After adjusting for comorbidities and other variables, patients with two risk alleles started dialysis 7.5 years earlier (Coef.=-7.53856, p=0.007) in a multivariate linear regression model. The analyses were adjusted for gender, comorbidities, smoking status, income and education level.

Conclusion

APOL1 mutations are a significant risk factor for the development of ESRD in South American individuals of African descent. The presence of two APOL1 risk alleles conferred up to 21-fold higher risk of ESRD and was associated with younger age at the start of dialysis.