Significant outcome signals from clinical associations of IgM aPL were inconsistent but noteworthy in (i) pregnancy loss for high-titre aCL, aβ2GPI, and aPS/PT, (ii) thrombosis driven by aPS/PT and (iii) organ-specific arterial events (retinal thrombosis and stroke) in isolated IgM phenotypes. This evidence concerns the gene ACLY and stroke disorder.