APOL1 and kidney disorder: To determine if presence of this duplication correlated with disease in heterozygous individuals (i.e. if apparent G0G1 heterozygotes by standard genotyping had additional copies of APOL1 at increased frequency), we used the PCR assay described above to genotype 123 African American patients with kidney disease (Table 1), and 255 African Americans without kidney disease, for the presence of this duplication.