On one hand, either lupus anticoagulants (LA), anticardiolipin IgM/IgG antibodies (aCL), and/or anti-β2-glycoprotein I IgG/IgM antibodies (anti-β2-GPI) must be persistently elevated on two occasions, a minimum of 12 weeks apart. This evidence concerns the gene CD40LG and systemic lupus erythematosus.