Factor XI deficiency in Iranians: its clinical manifestations in comparison with those of classic hemophilia.

BACKGROUND AND OBJECTIVES In patients with factor XI(FXI) deficiency the bleeding tendency is poorly correlated with plasma factor levels. The purpose of this study was to evaluate whether or not this discrepancy is also present in a large series of patients from Iran, a previously unexplored ethnic group. DESIGN AND METHODS In 28 FXI - deficient patients bleeding symptoms and their relation to FXI levels were compared with those of 100 patients with factor VIII (FVIII)deficiency (classic hemophilia), matched for severity of factor deficiency. RESULTS Spontaneous bleeding was definitely less frequentin FXI deficiency than in hemophilia, whereas postoperative and post-traumatic bleeding occurred with comparable frequencies. Among FXI-deficient patients the severity of symptoms was poorly correlated with FXI levels, mildly deficient patients bleeding almost as frequently as those severely deficient. In contrast, in patients with classic hemophilia there was a close relation between the severity of bleeding and degree of FVIII deficiency. INTERPRETATION AND CONCLUSIONS As in other ethnic groups, in Iranians factor XI deficiency is less severe than classic hemophilia and the bleeding tendency is poorly correlated to plasma factor levels.