Additional molecules including hemopexin, angiopoietin-like-4 and CD80 are associated with nephrotic syndrome and have also been shown to cause proteinuria in experimental animals (Garin et al. 2010; Lennon et al. 2008; Clement et al. 2011) but do not appear to be relevant to FSGS. Here, CD80 is linked to focal segmental glomerulosclerosis.