Malone et al. performed next-generation sequencing on 70 families with focal segmental glomerulosclerosis (FSGS) and discovered that 10% had variants in surprising 'old' genes, COL4A3 and COL4A4, which are involved in Alport syndrome and thin basement membrane nephropathy. These data show that a subset of renal manifestations associated with COL4A3 or COL4A4 variants cannot be distinguished from FSGS by clinical data or histopathology. Thus, a diagnosis of FSGS may sometimes fall within the spectrum of Alport syndrome.