To investigate whether EM can distinguish patients with a mono-allelic variant in COL4A3 or COL4A4 from patients with other glomerular diseases, we revised EM images from the patients with a mono-allelic variant in COL4A3 or COL4A4 (n = 7) and compared these with EM images from patients with other forms of FSGS (n = 14; Table 5). The gene discussed is COL4A4; the disease is focal segmental glomerulosclerosis.