APOL1 and kidney disorder: In summary, if the G1 and G2 alleles of APOL1 cause kidney disease, then there are several questions for which we have insufficient answers, including a mechanism of injury due to the G1 and G2 variants but not wild type APOL1, and an explanation for why up to 95% of people with two copies of G1 or G2 alleles do not develop FSGS.