A major strength of this study is that we were able to use a recently developed assay [16] to precisely assess the methylation status of the FOXP3 TSDR of CD25lowFOXP3+ cells, a feature that was lacking in the previous SLE studies [7], [8] or studies of this subset from healthy individuals [13]. This evidence concerns the gene FOXP3 and systemic lupus erythematosus.