Familial Congenital Labile Factor Deficiency with Syndactylism

Abstract

Of 7 siblings, 5 had syndactylism and bleeding tendency and occurred in both sexes. The parents were normal. Three members of the family, all with bleeding tendency, were studied extensively. One girl and 1 boy showed, in addition to labile factor deficiency, subnormal amts. of prothrombin in the plasma. The other boy had normal plasma prothrombin content. In the latter, clotting and bleeding times were slightly prolonged. The labile factor deficiency was associated with a lengthened one-stage prothrombin time, complete conversion of prothrombin to thrombin in the 2-stage test for the detn. of plasma prothrombin, retarded prothrombin consumption and low values for serum-prothrombin-conversion-accelerator. Evidence was obtained for the catalytic nature of the action of the labile factor.