Marchetti T, et al. - Experts evaluated the prevalence of aPL in a well-characterized SLE cohort and assessed their analytical performance and clinical relationship by testing criteria specificities including LA, aCL IgG and IgM, anti-β2-glycoprotein 1 (antiβ2GP1) IgG and IgM, as well as the non-criteria aPS-PT IgG and IgM and anti-β2GP1 domain 1 (aD1) IgG. Findings suggested that the non-criteria aPL aD1 IgG and aPS-PT IgG performed differently. In triple-positive samples, aD1 IgG was highly enriched. An association of aPS-PT IgG, jointly with LA, was seen with thrombotic events.