After rituximab therapy, CD20+ B-lymphocytes are rapidly depleted and they reappear to the peripheral blood (PB) after 5–12 months [6, 11, 12], preceded by an elevation of peripheral blood (PB) levels of BAFF [4].Elevated BAFF levels have also been reported in LON in rheumatic diseases, with a return to basal levels after LON [6], yet its role in LON development is unclear, as well as the underlying mechanisms involved in BAFF elevation. The gene discussed is TNFSF13B; the disease is rheumatic disorder.