NPHS1 and focal segmental glomerulosclerosis: Autoantibodies against nephrin, a key slit diaphragm protein of podocytes, are a newly identified factor in patients with primary podocytopathies such as minimal change disease (MCD) and primary focal segmental glomerulosclerosis (FSGS), and children with idiopathic nephrotic syndrome (INS) [1–6].