Factor VIIa in patients with C1-inhibitor deficiency.
In hereditary angioedema (HAE), normal C1-inhibitor (C1-INH) is low and the contact system activated. Recently, the findings of a tissue factor mutant selectively deficient in promoting the conversion of FVII to FVIIa, but with retained cofactor for FVIIa, made it possible to examine reliably the pre-existing content of FVIIa in HAE patients. This was of interest as FXIIa (mainly inhibited by C1-INH) is able to activate FVII directly. FVIIa in 21 remission HAE patients were within normal limits but nearly doubled as compared to their 23 normal siblings (p = 0.0017). Cold promoted activation of FVII (CPA) (common clot assay) was displayed in plasma of all 5 untreated patients (C1-INH function < 35%), but not in plasma of 2 patients treated prophylactically with danazol (C1-INH function about 40%). These results suggest that there is a minute, yet significant activation of FVII in patients with C1-INH deficiency.
Nielsen
E W
EW
Department of Anaesthesiology, Nordland Central Hospital, Bodø, Norway.
Morrissey
J
J
Olsen
J O
JO
Osterud
B
B
D000799:Angioedema / Q000235:genetics / Q000378:metabolism*; D003174:Complement C1 Inactivator Proteins / Q000172:deficiency*; D015942:Factor VIIa / Q000032:analysis*; D005190:Family; D005260:Female; D006801:Humans; D008297:Male
D003174:Complement C1 Inactivator Proteins; D015942:Factor VIIa