One‐stage and chromogenic FVIII:C assay discrepancy in mild haemophilia A and the relationship with the mutation and bleeding phenotype

Cid, Ana Rosa; Calabuig, Mar. G.; Cortina, Vicente; Casaña, Pilar; Haya, Saturnino; Moret, A.; Cabrera, Noelia; Aznar, José A.

doi:10.1111/j.1365-2516.2008.01781.x

Cited by 58 publications

(76 citation statements)

References 15 publications

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“…There are also two mutations causing inverse assay discrepancy. There are at least four more mutations causing assay discrepancy, and four other mutations causing inverse discrepant mild haemophilia A (8,11,12).…”

Section: Prevalence and Consequences Of Assay Discrepancymentioning

confidence: 99%

Assay discrepancy in mild haemophilia A

Armstrong

Hillarp²

2014

European J of Haematology

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There are three main methods used to assay factor VIII (FVIII) activity: the one-stage and two-stage clotting assays and the two-stage chromogenic method. The most commonly used assay for the diagnosis of haemophilia A is the automated one-stage FVIII assay. The classical two-stage FVIII assays are less frequently used. The chromogenic FVIII:C assay is a variant of the two-stage assay. It is easier to use and therefore used more commonly. Recently significant assay discrepancy has been recognised in the FVIII:C measurements in approximately one-third of mild haemophilia A patients. This so-called discrepant mild haemophilia A is characterised by a high ratio of one-stage/two-stage assay with one-stage FVIII levels that are typically more than double those of the two-stage coagulation assay. There are several mutations that destabilise the FVIIIa structure that can explain this result of a more pronounced decrease of the chromogenic FVIII:C activity compared with the one-stage activity. These mutations are clustered at the interfaces of the A1, A2 and A3 domains of the FVIII protein. The inverse discrepancy, where the one-stage assay gives lower FVIII:C results than the chromogenic assay, seems to be associated with mutations found close to important sites for thrombin cleavage or FIX binding. We are carrying out a study of mild haemophilia A samples from the Malm€ o Haemophilia Centre of families with a unique F8 genotype. The activity of FVIII will be measured using a chromogenic assay and two different one-stage assays. We hope to estimate the true size of assay discrepancy. Aim: This project will review assay discrepancy in mild/moderate haemophilia A and the risk of misdiagnosis. The overall aim is to estimate the size of the problem and to learn from the literature and experiences from our centre as well as to suggest recommendations on how to avoid misdiagnosis.

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Section: Prevalence and Consequences Of Assay Discrepancymentioning

confidence: 99%

Assay discrepancy in mild haemophilia A

Armstrong

Hillarp²

2014

European J of Haematology

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“…It may be that the presence or absence of bleeding in these reverse discrepancy patients depends on the genetic defect present and how the FVIII function is affected. Some reviews of previously diagnosed mild haemophilia have failed to identify any cases with totally normal one-stage FVIII assay with reduced two-stage clotting/chromogenic activity [10,11]. If the population of haemophiliacs selected for these studies had been initially diagnosed by one-stage assay there could be selection bias as any patients with normal one-stage FVIII may have been originally classified as normal and therefore excluded from the group under analysis.…”

Section: Steve Kitchenmentioning

confidence: 99%

New developments in laboratory diagnosis and monitoring

et al. 2010

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“…However, approximately 30% of patients show marked differences in FVIII:C activity when assayed by the three methods and are regarded as assay discrepant. [2][3][4] The differences in levels may be 2-fold or greater and for some patients, one or more of the FVIII:C assays may be in the normal range, potentially leading to an incorrect diagnosis.…”

Section: Introductionmentioning

confidence: 99%

Specific and global coagulation assays in the diagnosis of discrepant mild hemophilia A

Bowyer¹,

Veen²,

Goodeve

et al. 2013

Haematologica

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The activity of the factor VIII coagulation protein can be measured by three methods: a one or two-stage clotting assay and a chromogenic assay. The factor VIII activity of most individuals with mild hemophilia A is the same regardless of which method is employed. However, approximately 30% of patients show marked discrepancies in factor VIII activity measured with the different methods. The objective of this study was to investigate the incidence of assay discrepancy in our center, assess the impact of alternative reagents on factor VIII activity assays and determine the usefulness of global assays of hemostasis in mild hemophilia A. Factor VIII activity was measured in 84 individuals with mild hemophilia A using different reagents. Assay discrepancy was defined as a two-fold or greater difference between the results of the one-stage and two-stage clotting assays. Rotational thromboelastometry and calibrated automated thrombography were performed. Assay discrepancy was observed in 31% of individuals; 12% with lower activity in the two-stage assay and 19% with lower activity in the one-stage assay. The phenotype could not always be predicted from the individual's genotype. Chromogenic assays were shown to be a suitable alternative to the two-stage clotting assay. Thromboelastometry was found to have poor sensitivity in hemophilia. Calibrated automated thrombography supported the results obtained by the two-stage and chromogenic assays. The current international guidelines do not define the type of assay to be used in the diagnosis of mild hemophilia A and some patients could be misclassified as normal. In our study, 4% of patients would not have been diagnosed on the basis of the one-stage factor VIII assay. Laboratories should use both one stage and chromogenic (or two-stage) assays in the diagnosis of patients with possible hemophilia A.

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One‐stage and chromogenic FVIII:C assay discrepancy in mild haemophilia A and the relationship with the mutation and bleeding phenotype

Cited by 58 publications

References 15 publications

Assay discrepancy in mild haemophilia A

Assay discrepancy in mild haemophilia A

New developments in laboratory diagnosis and monitoring

Specific and global coagulation assays in the diagnosis of discrepant mild hemophilia A

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