Antibodies to factor XII: a possible predictive marker for recurrent foetal loss

Antibodies to factor XII (FXIIabs) have been demonstrated in some patients with the antiphospholipid syndrome (APS). The presence of these antibodies were shown to lead to statistically significantly reduced levels of FXII (p=0.02). In an extension to this study forty female patients with either primary APS (n=26) or systemic lupus erythematosus (APS positive) (n=14) were investigated for levels of factor XII, the presence of lupus anticoagulant and antibodies to cardiolipin, beta 2-glycoprotein I and factor XII. Twenty one of the forty patients had a history of foetal loss (>2, mean=2.6). Lupus anticoagulant positivity showed a weak association with foetal loss (odds ratio=1.1). While there was no association between the presence of antibodies to cardiolipin or beta 2-glycoprotein I with foetal loss, antibodies to factor XII showed a strong and statistically significant association (odds ratio=5.4, p=0.025).