ACTN4 and focal segmental glomerulosclerosis: Mutations in several genes are associated with familial forms of FSGS or nephrotic syndrome, including α-actinin-4 (here we use ACTN4 to designate the human gene or protein and Actn4 to designate the mouse gene or protein) [12], inverted formin 2 (INF2) [13], canonical transient receptor potential 6 (TRPC6) [14, 15], nephrin (NPHS1) [16], and podocin (NPHS2) [17].