NPHS1 and focal segmental glomerulosclerosis: Downregulation of nephrin has similarly been documented in many forms of acquired glomerular diseases, such as diabetic nephropathy [19–23], minimal change disease (MCD) [24,25], focal segmental glomerulosclerosis (FSGS) [26], membranous nephropathy [26,27], and others including IgAN, where reductions in NPHS1 expression correlate with increased proteinuria [28].