APOL1 and glomerulosclerosis: However, the virus that might interact with APOL1 to cause the more common idiopathic focal and segmental glomerulosclerosis has not been discovered, nor has a mechanism been uncovered for the proposed interaction between APOL1 and HIV or any other virus that would explain why all forms of glomerulosclerosis arise with the G1 or G2 alleles but not with the wild type APOL1 allele.