Factor XI deficiency and a platelet defect.

A patient with a lifelong bleeding tendency of moderate severity was found to have both factor XI deficiency and a long bleeding time. There was a significant deficiency of platelet factor 3, but other parameters of platelet function were normal. Infusion studies showed that both fresh plasma and platelet concentrate were required for complete correction of the haemostatic abnormalities, suggesting that these two defects were inherited coincidentally.