Indeed, anti-β2GPI antibody subpopulations are identified employing β2GPI as antigen, most commonly in immunoenzimatic or chemiluminescence assays; aCL tests usually detect antibodies reacting against cardiolipin complexed with β2GPI, and are thus referred to as “β2GPI-dependent aCL.” The latter assay allows identifying a broader antibody subpopulation, with a lower specificity for APS. This evidence concerns the gene ACLY and autoimmune polyendocrinopathy.