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PP.25.13: NON-ASSOCIATION OF APOL1 WITH RENAL TRAITS, BUT WITH BLOOD PRESSURE IN MIXED ANCESTRY SOUTH AFRICANS

Objective: The frequencies of APOL1 variants and their associations with chronic kidney disease (CKD) vary substantially in populations from Africa. Moreover, available studies have used very small samples to provide less reliable estimates of the frequencies of these variants in the general population. We determined the frequency of the two APOL1 risk alleles (G1 and G2) and investigated their association with renal traits in mixed-ancestry South Africans. Design and method: APOL1 risk variants (G1: rs60910145 and rs73885319; G2: rs71785313) were genotyped in 859 African mixed ancestry individuals using allele-specific TaqMan technology. Glomerular filtration rate was estimated (eGFR) using Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration equations. Results: The frequencies of rs73885319, rs60910145 and rs71785313 risk alleles were respectively, 3.6%, 3.4%, and 5.8%, resulting in a 7.2% frequency of the APOL1 two-risk allele (G1:G1 or G1:G2 or G2:G2). None of the genotypes was associated with prevalent CKD or eGFR assuming either dominant or log-additive genetic models. In similar models, significant associations were found between rs71785313 and systolic blood pressure (both p < 0.025), with a significant statistical interaction by diabetes status, p = 0.022. Conclusions: Although the APOL1 variants are not common in the Mixed Ancestry population of South Africa, our study does provide an indication that APOL1 variants, particularly, G2 may play a role in conferring a poor cardiovascular risk profile in this population. The association with renal diseases needs further exploration in patients with a more homogenous type of CKD.