It has been reported thatwomen with obstetric APS (without systemic thromboembolism) have lower aCL antibody titresthan patients with a thrombotic history.9 Data from a retrospective cohort study10 and also in the prospective European cohort7 suggest that low-titre aCL, defined as those between the 95th and99th percentiles rather than the 99th percentile as suggested in theICS criteria, are of clinical significance for women with purely obstetric APS. This evidence concerns the gene ACLY and autoimmune polyendocrinopathy.