Although these results are preliminary and we have not identified a clear causal variant that accounts for the increased FSGS risk in African Americans, they still suggest that, given the stronger association we observed for haplotype T-1 compared to haplotype E-1p, a close proxy for haplotype E-1 studied in [14], the causal variant has a larger penetrance than previously thought. While haplotype E-1 has a frequency close to 60% in African Americans, haplotype T-1 has a frequency close to 30%. This frequency likely reflects more faithfully the frequency of the causal variant than haplotype E-1, which shows that the prevalence of this variant is lower than recently thought and that, once identified, it may in fact have a clinical impact and significant clinical utility.
