We previously reported that the FCN1 mRNA level is elevated in peripheral blood mononuclear cells (PBMCs) of patients with vasculitis, including Takayasu arteritis (TA) and microscopic polyangiitis (MPA); specifically, we observed elevated expression of FCN1 in macrophages in the inflamed regions of surgical aorta specimens from TA patients14 and surgical glomeruli specimens taken from MPA patients15. This evidence concerns the gene FCN1 and vasculitis.