However, an IFN signature is found in only 50–80% of SLE patients (Baechler et al., 2003; Bennett et al., 2003; Crow and Wohlgemuth, 2003) and the IFN-induced gene signature assessed in longitudinal studies may not correlate with disease activity (Landolt-Marticorena et al., 2009; Petri et al., 2009). This evidence concerns the gene IFNA1 and systemic lupus erythematosus.