To ensure comparability of clinical studies, within a research setting presence of APS is usually assumed when the criteria of the so-called Sydney-classification are fulfilled, i.e. persistent positivity for lupus anticoagulant (LA), anti-cardiolipin (aCL) or anti-β2-glycoprotein I (aβ2-GPI) IgG or IgM in addition to the typical clinical manifestations [2]. This evidence concerns the gene CD40LG and autoimmune polyendocrinopathy.