ACTN4 and familial nephrotic syndrome: Podocytes have become the focus of attention in recent years because of other gene mutations that have been identified which encode proteins at, or in association with the podocyte slit diaphragm and cause hereditary nephrotic syndrome, such as NPHS1 (nephrin) [22], ACTN4 (α actinin-4) [42] and NPHS2 (podocin) [43], of which TRPC6 is the latest addition.