Circulating permeability factors may be involved in the pathogenesis of minimal change disease and FSGS [2]. For example, Watts et al. discovered that circulating anti-nephrin antibodies were related to the etiology of minimal change disease and that punctuate IgG in podocytes correlated with anti-nephrin antibodies [3]. In a recent multicenter observational study, Shirai et al. reported a possible role for circulating anti-nephrin antibodies in FSGS recurrence after kidney transplantation [4]. This evidence concerns the gene NPHS1 and focal segmental glomerulosclerosis.