COL4A4 and focal segmental glomerulosclerosis: Certain genes have been identified in patients with FSGS and NS [4,5], such as components of the glomerular basement membrane (GBM), including the α3, α4, and α5 chains of type IV collagen, encoded by COL4A3, COL4A4, and COL4A5 respectively, and the structural proteins of the podocyte slit membrane, like nephrin and podocin, encoded by NPHS1 and NPHS2, respectively.