PB0381 - Red blood cell inclusions of non-muscle myosin IIA associate with GATA1-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)

LV

Leonard Vater

Medical Student
Institut für Transfusionsmedizin, Universitätsmedizin Greifswald.
Greifswald, Mecklenburg-Vorpommern, Germany
José RIVERA Rivera, PhD

PhD
Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Pascual Parrilla, Murcia, Spain
Murcia, Murcia, Spain
JW

Jan Wesche

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

Carmen Freyer

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

Sandra Ohlenforst

MD
Institute of Experimental Haematology and Transfusion Medicine, University Clinic Bonn, Germany.
Bonn, Nordrhein-Westfalen, Germany
Kathleen Freson, PhD

Professor
Department of Cardiovascular Sciences, Center for Molecular and Vascular Biology, KU Leuven, Leuven, Belgium.
Leuven, Vlaams-Brabant, Belgium
Andreas Greinacher, MD

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

Background: GATA1-related thrombocytopenia (GATA1-RT) is a X-linked inherited platelet disorder (IPD) featured by thrombocytopenia, enlarged platelets and dyserythropoietic features caused by mutations in the transcription factor GATA binding protein 1 (GATA1). 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 GATA1-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 GATA1-RT on the blood smear.

Methods: Blood smears were stained with May-Grünwald-Giemsa technique, and with a panel of antibodies against 13 markers of platelet structures (granules, cytoskeleton, surface receptors), and assessed with standard light- and immunofluorescence-microscopy.

Results: 7 genetically confirmed GATA1-RT-individuals belonging to 5 unrelated families were investigated. Subjects were 4 males and 3 females. Their mean platelet count was 80,000/µL (range 30-90,000). By light-microscopy, a heterogeneous platelet population with some large platelets in combination with red blood cell anisopoikilocytosis was observed. By immunofluorescence-microscopy, we found small inclusion bodies consisting aggregates of non-muscle myosin II A, heavy chain (NMMHC-IIA) in the erythrocytes as the most conspicuous finding, which was present in all subjects. We also found a reduction of alpha granule markers in 6 patients. By systematic re-analysis of blood smears from a cohort of patients with 20 different forms of IPD, we found a similar expression of NMMHC-IIA in the red blood cell exclusively in subjects with GFI1B-related thrombocytopenia (GFI1B-RT), which also associates with dyserythropoiesis.

Conclusion(s): Red blood cell aggregates of NMMHC-IIA associate with GATA1-RT and, possibly, with GFI1B-RT. This finding may represent a novel marker of dyserythropoiesis, and it enables recognition of GATA1-RT by immunofluorescence microscopy on the blood smear.