APTT mixing studies showed no correction of prolonged APTT (the lupus anticoagulant test was negative), FVIII activity was unmeasurably low (<0.1%), factor IX activity was moderately low (6.9%), and the modified Bethesda test showed high titer of inhibitory autoantibodies (2283 BU). Here, F8 is linked to systemic lupus erythematosus.