Given the identification of PRDM1 as a susceptibility gene for human SLE and RA (Gateva et al, 2009; Raychaudhuri et al, 2009; Zhou et al, 2011), we next investigated whether Prdm1ihCd2/+ mice develop an autoimmune phenotype with progressing age. This evidence concerns the gene PRDM1 and systemic lupus erythematosus.