Cold agglutinin syndrome (CAS), caused by Immunoglobulin M (IgM) antibodies that agglutinate at low temperatures, is exceptionally rare in SLE with few cases being reported in the literature [3,4]. Although AIHA is a relatively rare manifestation, it can precede the diagnosis of SLE or be one of its presenting features. The gene discussed is CD40LG; the disease is cold agglutinin disease.