Abstract Number: PB1444
Meeting: ISTH 2020 Congress
Background: Platelet size is one of the important distinguishing features for different inherited thrombocytopenias (ITs) and immune thrombocytopenia (ITP). MYH9-related disease (MYH9-RD) is an IT that can be suspected if peripheral blood smear shows Dohle-like cytoplasmic inclusion bodies in neutrophils or if abnormal localization of non-muscle myosin heavy chain IIA is detected by means of immunofluorescence microscopy. Giant size of platelets is another diagnostic feature in MYH9-RD. But mean platelet volume can be underevaluated by the electronic counter in patients with extreme platelet macrocytosis. Flow cytometry of platelets is another way to assess platelet size among other parameters.
Aims: To assess the possibility of distinguishing patients with MYH9-RD from patients with other ITs and ITP based on parameters of flow cytometry of platelets.
Methods: We enrolled 24 patients (17 children and 7 adults) with MYH9-RD, 35 patients with other ITs and 111 patients with persistent and chronic ITP. Diagnosis was confirmed by identification of causative mutations in all cases of ITs. Forward scattering (FSC) parameter prior to activation was used for characterization of platelet size. ROC curve analysis was used to identify optimal cut-off values.
Results: Identified cut-off values for FSC had 96.8% specificity and 100% sensitivity in distinguishing MYH9-RD from other ITs and 93.1% specificity and 100% sensitivity in distinguishing MYH9-RD from ITP. AUC was 0.992 (CI 95% 0.973; 1.00) and 0.991 (CI 95% 0.978; 1.00) respectively. Based on FSC parameter patients with patients with Bernard-Soulier syndrome (BSS) had the nearest to MYH9-RD platelet size among all ITs, but BSS and MYH9-RD were easily separated based on expression of CD42b.
Conclusions: Diagnosis of MYH9-RD can be suspected not only after light or immunofluorescence microscopy of peripheral blood smear but also by means of flow cytometry of platelets. Patients with MYH9-RD can be distinguishing from patients with other ITs and ITP based on FSC parameter.
To cite this abstract in AMA style:Fedorova D, Ignatova A, Polokhov D, Ponomarenko E, Panteleev M, Zharkov P. Flow Cytometry of Platelets: A Way for Distinguishing Patients with MYH9-related Disease from Patients with Other Inherited Thrombocytopenias and Immune Thrombocytopenia [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/flow-cytometry-of-platelets-a-way-for-distinguishing-patients-with-myh9-related-disease-from-patients-with-other-inherited-thrombocytopenias-and-immune-thrombocytopenia/. Accessed November 29, 2023.
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