ABSTRACT
Background@#The clinical phenotype of hemophilia A (HA) does not always correlate with severity.Similarly, the presence of inhibitors does not necessarily increase the risk of bleeding.This paradox between clinical and laboratory findings may be partially attributed to non-modifiable factors, such as blood group, which is known to influence FVIII levels in healthy individuals. Our aim was to assess the effect of ABO blood group antigens on FVIII levels across the severity spectrum of HA and risk of inhibitor development. @*Methods@#Data of consecutive patients with HA who visited the coagulation unit of a northern Indian tertiary care hospital between 2010‒2021 were reviewed. Patients with missing blood group data, transfusion histories, or baseline FVIII levels were excluded. @*Results@#Mild, moderate, and severe HA was present in 41 (6.9%), 72 (12.2%), and 479 (80.9%) patients, respectively. There were no differences in the FVIII levels among the various blood groups across the HA severity spectrum. Inhibitors were administered to 35 patients (5.9%). In the multivariate analysis, blood group A was an independent risk factor for the development of inhibitors (adjusted odds ratio 2.70, P =0.04) after adjusting for age at onset of bleeding, FVIII transfusion, age at first FVIII transfusion, and severity of HA. @*Conclusion@#Unlike what is observed in healthy individuals, blood group did not influence residual FVIII levels across the severity spectrum of HA. Patients in group A had a higher risk of developing inhibitors.
ABSTRACT
Background@#Platelet aggregation studies using conventional light transmission aggregometry (LTA) have several disadvantages and require strict pre-analytical measures for reliable results.We aimed to examine the utility of flow cytometric platelet aggregation (FCA) assay in detecting platelet function defects (PFDs) in patients with a history of bleeding symptoms. @*Methods@#Sixty-four participants (24 patients and 40 healthy controls) were included in this study.LTA and FCA assay were performed simultaneously in patients and healthy controls. In the FCA assay, two portions of platelets from the same individual were labeled separately with CD31-FITC and CD31-PE. After mixing and stimulation with agonists, the double-colored platelet aggregates were visualized using a flow cytometer. The results generated using the two techniques were compared and correlated. @*Results@#The patients’ median age was 17 years (range, 3‒72 yr) with a male-to-female ratio of 1:1.7. There was substantial agreement between LTA and FCA assay in detecting a PFD (κ=0.792). Four patients showing a Glanzmann thrombasthenia-like pattern on LTA exhibited an abnormal FCA. A functional defect in collagen binding was detected on the FCA assay conducted in two immune thrombocytopenic patients with severe bleeding. @*Conclusion@#FCA assay can be used to identify functional defects in platelets, with potential applications in thrombocytopenic individuals. It also facilitates the diagnosis of inherited bleeding disorders with platelet defects.
ABSTRACT
Background@#Platelet aggregation studies using conventional light transmission aggregometry (LTA) have several disadvantages and require strict pre-analytical measures for reliable results.We aimed to examine the utility of flow cytometric platelet aggregation (FCA) assay in detecting platelet function defects (PFDs) in patients with a history of bleeding symptoms. @*Methods@#Sixty-four participants (24 patients and 40 healthy controls) were included in this study.LTA and FCA assay were performed simultaneously in patients and healthy controls. In the FCA assay, two portions of platelets from the same individual were labeled separately with CD31-FITC and CD31-PE. After mixing and stimulation with agonists, the double-colored platelet aggregates were visualized using a flow cytometer. The results generated using the two techniques were compared and correlated. @*Results@#The patients’ median age was 17 years (range, 3‒72 yr) with a male-to-female ratio of 1:1.7. There was substantial agreement between LTA and FCA assay in detecting a PFD (κ=0.792). Four patients showing a Glanzmann thrombasthenia-like pattern on LTA exhibited an abnormal FCA. A functional defect in collagen binding was detected on the FCA assay conducted in two immune thrombocytopenic patients with severe bleeding. @*Conclusion@#FCA assay can be used to identify functional defects in platelets, with potential applications in thrombocytopenic individuals. It also facilitates the diagnosis of inherited bleeding disorders with platelet defects.