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Factor × Roma: a congenital factor × variant defective at different degrees in the intrinsic and the extrinsic activation
Author(s) -
Stefano V. De,
Leone G.,
Ferrelli R.,
Hassan H. J.,
Macioce G.,
Bizzi B.
Publication year - 1988
Publication title -
british journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.907
H-Index - 186
eISSN - 1365-2141
pISSN - 0007-1048
DOI - 10.1111/j.1365-2141.1988.00345.x-i1
Subject(s) - factor v , intrinsic factor , thromboplastin , coagulopathy , factor xii , heterozygote advantage , clotting factor , factor x , factor xi , medicine , immunology , endocrinology , chemistry , coagulation , biology , biochemistry , thrombin , platelet , gene , thrombosis , vitamin b12 , allele
A factor × molecular variant was identified in a 13‐year‐old girl affected by a bleeding tendency. Factor × antigen levels and activation by Russel's viper venom (tested both by clotting and amidolytic assays) were normal. Factor × crossed immunoelectrophoresis was found to be identical to that of the control plasma. Factor × functional activity was low (3% of the normal) if tested by PTT‐derived assays, whereas it was found at intermediate levels (about 30–50% of the normal) if measured by prothrombin time‐derived assays. The defect in the extrinsic activation was more clearly disclosed using as activating agent thromboplastin from ox brain. The factor × of the patient was completely adsorbed by aluminium hydroxide. The parents of the propositus (first degree cousins) showed factor × functional levels compatible with a condition of heterozygosity for the abnormality. This factor × molecular variant appears different from the other ones so far described and was named ‘Factor × Roma’.