APOL1 and glomerular disorder: In initial reports, a small but statistically significant correlation was reported for glomerulosclerosis with a single allele of G1 or G2, suggesting a potential dominant effect (or what is sometimes termed a semi-dominant effect, in which one allele results in a phenotype but two alleles result in a stronger phenotype); in support, one of the subsequent analyses of the APOL1 G1 and G2 alleles found a risk of glomerular disease that fit a semi-dominant or additive model [13], [36].