CD4 and focal segmental glomerulosclerosis: Since idiopathic nephrotic syndrome (FSGS and minimal change disease) was linked to T cell dysfunction nearly half‐century ago,[1] numerous studies have shown that various subsets of T cells, including CD4 T cell,[2, 3, 4] CD8 T cell,[5] or regulatory T cells (Tregs),[6, 7] correlate positively or negatively with the progression of FSGS, respectively.