ATM and systemic lupus erythematosus: To the best of our knowledge, this is the first study in SLE patients showing underexpression of the XPA, XPC, HUS1, MRE11A, NBN, RAD50, RAD51, RPA1, TP53BP1 and ATM genes involved in DNA damage repair and signaling pathways, as well as overexpression of PPP1R15A, BARD1, BBC3, BRCA1 genes involved in the apoptosis pathway.