As indicated by our results, whether it is for IgM–aCL or IgM–aβ2GPI, the AUCs were lower than those of IgG–aPL and IgA–aPL; however, the diagnostic efficacy for APS was improved when IgM–aPL was used in combination with the IgG isotype. This evidence concerns the gene ACLY and autoimmune polyendocrinopathy.