Fletcher Factor Deficiency: Family Study and Detection

Eight of 11 children of a known Fletcher factor-deficient individual were found to have normal activated partial thromboplastin times, normal levels of factors VIII, IX, XI, and XII, and a mean Fletcher factor level of 53% (range 40%-72%), suggesting a heterozygous state for the genecontrolling Fletcher factor production. All partial thromboplastin time reagents containing celite or kaolin were sensitive to Fletcher factor deficiency, while one reagent containing ellagic acid did not detect this abnormality. The finding of an abnormal partial thromboplastin time that is corrected by a 10-min incubation period is presumptive evidence for Fletcher factor deficiency.