IRF5 and systemic lupus erythematosus: It has recently been demonstrated that a structural insertion/deletion (in/del) variation in exon 6 of the IRF5 gene is associated with an IRF5-SLE haplotype [8], [10]; the presence of the 30-nt insertion (Fig. 1C; exon 6c) is correlated with a risk haplotype for SLE development.