Abstract Number: PB0843
Meeting: ISTH 2020 Congress
Background: Haemophilia A is an X-linked hereditary bleeding disorder that occurs predominantly in males and is a result of a deficiency in coagulation factor VIII. The disease is classified as mild, moderate or severe, depending on residual factor VIII activity, with each severity having a different phenotype (pattern of bleeding). Within the category of severe haemophilia A, however, the phenotype also differs. There have been several postulations regarding the differing phenotypes, one of which proposes that increased platelet activation status accounts for a milder bleeding phenotype in some patients, despite similar levels of residual factor VIII. However, previous studies have shown conflicting results in this regard.
Aims: To compare platelet activation in patients with haemophilia A and normal, healthy controls. In addition, the status of platelet activation in patients with severe haemophilia A was investigated to determine whether there was a relationship between increased platelet activation and severity of the bleeding phenotype.
Methods: The principle methodology involved measuring markers of platelet activation: P-selectin(CD62P), activated glycoprotein IIbIIIa (PAC-1), monocyte-platelet aggregates, using immunophenotyping by flow cytometry. Other variables were also measured or obtained from the history e.g.: ABO blood grouping, platelet count, age of patient, age of first bleed, presence or absence of arthropathy and number of joints involved.
Results: Increased expression of only P-selectin was demonstrated in the patient group (n=19) compared to the control group (n=14). There was no relationship between the expression of any of the platelet activation markers and severity of the phenotype i.e. presence of arthropathy, number of joints involved.
Conclusions: The study was unable to confirm an association between an increase in platelet activation status and a milder bleeding phenotype in patients with severe haemophilia A. A limiting factor was the small patient sample available. Larger studies are warranted to more accurately investigate platelet activation in these patients.
To cite this abstract in AMA style:Potgieter J, Chetty T, Durandt C. Platelet Activation in Patients with Severe Haemophilia A [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/platelet-activation-in-patients-with-severe-haemophilia-a/. Accessed October 2, 2023.
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