PB0386 - Increased platelet expression of the transcriptional suppressor ETV6 can be detected by immunofluorescence on the blood smear and associates with ETV6-related thrombocytopenia

Sunday, June 25, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

Carlo Zaninetti, MD, PhD

Medical Doctor
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald.
Greifswald, Mecklenburg-Vorpommern, Germany

Co-Author(s)

MB

Marcel Baschin

MD
Pädiatrischen Onkologie und Hämatologie der Klinik und Poliklinik für Kinder- und Jugendmedizin, Universitätsmedizin Greifswald. Institut für Transfusionsmedizin, Universitätsmedizin Greifswald.
Greifswald, Mecklenburg-Vorpommern, Germany
LV

Leonard Vater

Medical Student
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald.
Greifswald, Mecklenburg-Vorpommern, Germany
AK

Anna Karastaneva

MD
Division of Pediatric Hematology and Oncology, Department of Pediatric and Adolescent Medicine, Medical University of Graz, Graz, Austria.
Graz, Steiermark, Austria
SH

Susanne Holzhauer

MD
Klinik für Pädiatrie mit Schwerpunkt Onkologie und Hämatologie, Universitätsmedizin Berlin.
Berlin, Berlin, Germany
CF

Carmen Freyer

Medical laboratory scientist
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald.
Greifswald, Mecklenburg-Vorpommern, Germany
MS

Markus G. Seidel

MD, Professor
Division of Pediatric Hematology and Oncology, Department of Pediatric and Adolescent Medicine, Medical University of Graz, Graz, Austria.
Graz, Steiermark, Austria
Andreas Greinacher, MD

Professor; Head of Institute
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald.
Greifswald, Mecklenburg-Vorpommern, Germany

Background: Inherited thrombocytopenias (IT) sometimes present with additional, acquired manifestations beyond hemostasis. ETV6-related thrombocytopenia (ETV6-RT), as well as IT due to mutations in RUNX1 and ANKRD26, causes mild-to-moderate thrombocytopenia with normal platelet size and makes the patients prone to develop hematological malignancies. The transcriptional suppressor ETV6 is usually located in the nucleus of megakaryocytes and redistributes preferentially into the cytoplasm when its DNA-binding properties are impaired by mutations. We have established an immunofluorescence-based method for phenotyping platelets on the blood smear, which we have validated as a screening tool for 9 different forms of IPD, for which typical changes of platelet structure can be detected. For ETV6-RT, no specific morphologic changes recognizable by immunofluorescence on the blood smear, have been reported so far.

Aims: To establish an immunofluorescence-based screening method for ETV6-RT on the blood smear.

Methods: We assessed blood smears by light- and immunofluorescence-microscopy upon staining with May-Grünwald-Giemsa method and with a set of antibodies against 13 markers belonging to different platelet structures (granules, cytoskeleton, surface receptors) and ETV6 protein. Antibody binding was visualized by fluorescence-labelled secondary antibodies.

Results: We investigated 11 patients from 6 unrelated families with confirmed ETV6-RT. Platelet expression of ETV6 was observed in all patients, which was markedly increased compared to healthy controls and individuals affected with IT other than ETV6-RT or acquired platelet disorders. In addition, abnormalities of dense granule markers (reduction of granule number; diffused distribution of the staining; granule structure presenting on the outer membrane) were reported in all but one patient.

Conclusion(s): Increased platelet expression of ETV6 and evidence of dense granule abnormalities are a feature of ETV6-RT. Due to the ethical implications, patients have to be informed about the potential association of ETV6-RT with an increased risk for hematological malignancies and should provide explicit consent to perform the investigation.