develop thromboembolic complications [8] and/or recurrent miscarriages [10].One other woman with FXII deficiency had a very low PAI-1 (plasminogen activator inhibitor) level and her OHP was below the mean for the control group. This may indicate that the OHP test could be a useful diagnostic tool for global assessments of overall thrombotic or hemorrhagic risk in individuals with combined genetic defects.Although the number of subjects is relatively small, we believe that these results are promising and may indicate that determination of OHP could be a method of choice for recognizing prothrombotic conditions associated with FXII deficiency and for distinguishing individuals with similarly low FXII levels. It seems that this assay (rather than the simple FXII concentration) could be used as a predictor of possible thrombotic risk. References