Fletcher Factor Deficiency: A Report of Three Unrelated Cases

S ummary . The authors report three unrelated patients who apparently have a severe deficiency of the ‘Fletcher factor’. None had a haemorrhagic tendency, and all had normal bleeding times, prothrombin times and thrombin times. All three showed defective intrinsic thromboplastin production, as evidenced by much prolonged kaolin activated partial thromboplastin time (PTT). None had deficiencies of factors VIII, IX, XI or XII. The prolonged PTT of each failed to shorten when his plasma was mixed with proven Fletcher deficient plasma. The plasma of one was assayed with plasma from a reference case of Fletcher deficiency and found to contain less than 1% of the normal activity. The prolonged PTT of each came down into or near the normal range on longer kaolin activation.