The target antigens, Sip1 in our study and α-enolase in the study by Lee and colleagues, were recognized only by IgM of patients with BD and patients with other forms of primary vasculitis, whereas no serum from patients with other autoimmune diseases or from healthy subjects had specific IgM with an OD reading in ELISA higher than the cutoff level. The gene discussed is CD40LG; the disease is autoimmune disease.