The detailed analysis of the Sle2c locus revealed a complex architecture with a total of four genes so far associated with lupus susceptibility: Cdkn2c, which regulates B1a cell expansion, the original selecting phenotype for Sle2c (8), a protective allele of Csf3r (11), a variant of Skint6 associated with T cell activation (15) and now a variant of sNASP that amplifies autoimmunity and aggravate tissue pathology. This evidence concerns the gene CSF3R and systemic lupus erythematosus.