It was also observed that the frequency of PD-1+/CXCR5+ follicular helper T (TFH) cells was significantly increased in BXD2 mice, which spontaneously develop autoantibodies and subsequent glomerulonephritis, offering a useful animal model to study autoimmune lupus, compared with wild-type mice (Kim et al. 2015). The gene discussed is PDCD1; the disease is glomerulonephritis.