Abstract Number: PB1505
Meeting: ISTH 2020 Congress
Theme: Platelet Disorders and von Willebrand Disease » Platelet Function Disorders, Hereditary
Background: Germline mutations in RUNX1 are associated with an autosomal dominant disorder characterized by thrombocytopenia, platelet dysfunction and predisposition to acute myeloid leukemia (AML). Overestimating the pathogenicity of new variants can lead to unnecessary worry about a potential risk to develop malignancies.
Aims: To evaluate the pathogenicity of new variants in RUNX1 identified in three unrelated women (P1, P2, P3) with a life-long history of mild thrombocytopenia and moderate bleeding.
Methods: We performed platelet phenotyping (flow cytometry, aggregation studies), and molecular analysis by high-through-sequencing (HTS). Ultrapure platelets were isolated by filtration+immunoselection (3 patients, and 5 controls). Platelet RNA was analyzed using Clariom-D Array (≈540 000 transcripts). In P1 we also evaluate proplatelet formation in megakaryocytes (Mks) differentiated from CD34+ peripheral blood cells.
Results: Only P1 and P2 showed functional platelet abnormalities (reduced aggregation and granule secretion). By HTS we identified new heterozygous variants in RUNX1: c.802C< T in P1; c.586A>G in P2; c.476A>G in P3. The analysis of the expression of 15 genes recognized as targets of RUNX1 (including MYL9, MYH9) was confirmed to be altered in P1 and P2 (30.8% and 38.5% similarity to controls), but not in P3 (92.7% resemblance). Similarly, the evaluation of 100 genes reported to be downregulated in the transcriptome of a RUNX1 patient (Sun, JTH 2007), showed 74.7%, 67.7% and 7.1% of them had lower expression in P1, P2, and P3, respectively. Culture of CD34-Mks from patient P1 showed reduced pro-platelet formation. Transcriptome analysis (P1 and P2 vs. controls) revealed that 25% of top 75 downregulated genes encode for cytoskeleton proteins.
Conclusions: Our study supports the pathogenicity of the RUNX1 variants identified in P1 and P2, but not in P3. Platelet transcriptome analysis can be a useful tool in the pathogenic characterization of new molecular variants affecting transcription factor genes in patients with inherited thrombocytopenias. [PI17/01311 -FMM AP172142019]
To cite this abstract in AMA style:
Palma-Barqueros V, Ruiz-Pividal JF, Bastida JM, Bohdan N, López-Andreo MJ, Teruel Montoya R, Rodriguez-Alen A, Padilla J, Revilla N, Marin-Quilez A, Benito R, Gonzalez-Porras JR, Vicente V, Lozano ML, Rivera J, On Behalf of the Project “Caracterización Funcional y Molecular de Trastornos Plaquetarios Congénitos” , Grupo de Trabajo de Patología Hemorrágica de la SETH . Strategies for Analysis of Novel Molecular Variants in the RUNX1 Gene as a Cause of Familial Platelet Disorder with Predisposition to Acute Myeloid Leukemia (FPD/AML) [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/strategies-for-analysis-of-novel-molecular-variants-in-the-runx1-gene-as-a-cause-of-familial-platelet-disorder-with-predisposition-to-acute-myeloid-leukemia-fpd-aml/. Accessed March 21, 2024.« Back to ISTH 2020 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/strategies-for-analysis-of-novel-molecular-variants-in-the-runx1-gene-as-a-cause-of-familial-platelet-disorder-with-predisposition-to-acute-myeloid-leukemia-fpd-aml/