patterns [e.g., of the interferon-regulatory factor (IRF)-5 gene] have been linked to the development of SLE [4–7]. Of the genetic susceptibility regions identified, many relate to alleles that are well-established contributors to immune cell pathways, such as IRF-5 or tumor necrosis factor superfamily member 4 (TNFSF4) [8,9]. These discoveries have largely shaped our understanding of a genetic predisposition to SLE, although the clinical discordance between monozygotic twins strongly indicates that genetic factors are not sufficient to lead to clinically defined SLE.
