The binding of autoimmune anticardiolipin antibodies to phospholipid has been shown to require a plasma cofactor, beta-2-glycoprotein 1 (beta2-GPI). Antibodies against beta2-GPI are associated with both venous and arterial thrombosis in adults and have been suggested as a new antiphospholipid syndrome marker. We present six children with cerebral thrombosis at the age of 0-12 months, who had IgG antibodies to beta2-GPI (titers 26, 29, 31, 39, 101 and 109 SGU, when 20 SGU was the cut-off). In at least four patients, the conventional antiphospholipid markers (lupus anticoagulant and IgG and IgM anticardiolipin) were negative. All six children had normal results in the other routine thrombophilia assays (thrombin time, antithrombin, protein C, protein S, factor V Leiden mutation, prothrombin mutation).
Conclusion: the anti-beta-2 glycoprotein 1 assay, requiring only 5 microl serum, may be a useful addition to antiphospholipid-antibody diagnostics in cases of paediatric stroke.