Although it is unclear to what extent advanced CKD in our participants without kidney biopsies was due to HIVAN/FSGS or hypertension, the strong association between APOL1 high-risk genotypes and our clinical case definition suggests that these etiologies may be relatively common, and that diabetic kidney disease and other causes of proteinuric renal failure not associated with APOL1 risk alleles are relatively uncommon. This evidence concerns the gene APOL1 and diabetic kidney disease.