NPHS1 and familial nephrotic syndrome: Mutations in the NPHS1 gene that encodes nephrin, are characterized by congenital nephrotic syndrome and inactivation of nephrin, which results in the disappearance of the slit diaphragm, large amounts of proteinuria, and death in mice (Kestila et al., 1998; Ruotsalainen et al., 1999).