Along this line, gating analyzes to describe cell populations stained positively for FOXP3 total but negatively for FOXP3 exon 2 may be misleading and define FOXP3 isoform ratios improperly, as described for peripheral blood from patients with giant cell arteritis (58), vasculitis (59), or anti-phospholipid syndrome (60). The gene discussed is FOXP3; the disease is vasculitis.