This together with high B cell levels of phosphorylated Rad52 and low levels Zfp318 indicated that in murine and human lupus, IgD autoantibodies stem from extensive B cell Sμ–σδ recombination, as also supported by high levels of AID, rather than Zfp318-dependent alternative splicing of primary VHDJH−μ-s-m-Cδ-s-m RNA transcripts. Here, RAD52 is linked to systemic lupus erythematosus.