Mutations of factor VIII cleavage sites in hemophilia A
J Gitschier, S Kogan, B Levinson and EG Tuddenham
Howard Hughes Medical Institute, University of California, San Francisco
94143.
Hemophilia A is caused by a defect in coagulation factor VIII, a protein
that undergoes extensive proteolysis during its activation and
inactivation. To determine whether some cases of hemophilia are caused by
mutations in important cleavage sites, we screened patient DNA samples for
mutations in these sites by a two-step process. Regions of interest were
amplified from genomic DNA by repeated rounds of primer- directed DNA
synthesis. The amplified DNAs were then screened for mutations by
discriminant hybridization using oligonucleotide probes. Two cleavage site
mutations were found in a survey of 215 patients. A nonsense mutation in
the activated protein C cleavage site at amino acid 336 was discovered in a
patient with severe hemophilia. In another severely affected patient, a
mis-sense mutation results in a substitution of cysteine for arginine in
the thrombin activation site at amino acid 1689. This defect is associated
with no detectable factor VIII activity, but with normal levels of factor
VIII antigen. The severe hemophilia in this patient was sporadic; analysis
of the mother suggested that the mutation originated in her gametes or
during her embryogenesis. The results demonstrate that this approach can be
used to identify factor VIII gene mutations in regions of the molecule
known to be important for function.
Volume 72,
Issue 3,
pp. 1022-1028,
09/01/1988
Copyright © 1988 by The American Society of Hematology
