Three patients had a modest increase in preexisting anti-CL antibodies, and 3 patients developed a de novo IgG or IgM anti-CL antibody of > 20 U. Of these, 1 with SLE had been previously positive, 1 with RA had a previous clot without anti-phospholipid antibodies, and 1 had eosinophilic granulomatosis with polyangiitis (EGPA). The gene discussed is CD40LG; the disease is systemic lupus erythematosus.