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Updated: Jul 9, 2026

Tail Vein Transection Bleeding Model in Fully Anesthetized Hemophilia A Mice
Published on: September 30, 2021
Tyr346-->Cys mutation results in factor VIII:C assay discrepancy and a normal bleeding phenotype - is this mild
1Department of Haematology, Nottingham University Hospitals NHS Trust, Queens Medical Centre Campus, Nottingham, UK.
Abstract:
Patients with mild haemophilia A may have a discrepancy in the factor VIII (FVIII) level when measured with a one-stage assay (FVIII:C1) compared with a two-stage assay (FVIII:C2). This discrepancy usually results in the one-stage level being higher than the two-stage level. A F8 mutation resulting in a Tyr346-->Cys substitution within the a1 interdomain region has been described which results in the converse assay discrepancy. We report four individuals (three families) who have this mutation. Mean FVIII:C1 level was 25 IU dL(-1) compared with a mean FVIII:C2 level of 63 IU dL(-1). These individuals had presented opportunistically and did not have a clinically significant bleeding disorder. The bleeding phenotype correlated with the two-stage assay result rather than the one-stage result. FVIII replacement therapy does not appear to be required for these individuals.
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