Double negative B cells (DNB), marked by their CD27 and IgD negativity, have been shown to be elevated in systemic autoimmune diseases such as systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS), and associated with renal impairment, suggesting a pathogenic role in autoimmunity (13–15). The gene discussed is CD27; the disease is systemic lupus erythematosus.