Rio-Machín, AnaMenezes, JulianeMaiques-Diaz, AlbaAgirre, XabierFerreira, Bibiana IAcquadro, FrancescoRodriguez Perales, SandraJuaristi, Karmele AAlvarez, SaraCigudosa, Juan C2025-01-282025-01-282012-04Haematologica . 2012 Apr;97(4):534-7https://hdl.handle.net/20.500.12105/26159the authors would like to thank all the co-workers in our laboratory for their excellent technical assistance. This work was supported by an INTRASALUD project PI 08-0440 grant to JCC, a PhD fellowship from Obra Social-Fundacion "La Caixa" to JM, and a PhD fellowship from the Ministry of Science and Innovation to AdR-M.The disruption of RUNX1 function is one of the main mechanisms of disease observed in hematopoietic malignancies and the description of novel genetic events that lead to a RUNX1 loss of function has been accelerated with the development of genomic technologies. Here we describe the molecular characterization of a new t(4;21)(q21;q22) in a de novo myelodysplastic syndrome that resulted in the deletion of the RUNX1 gene. We demonstrated by quantitative real-time RT-PCR an almost complete depletion of the expression of the RUNX1 gene in our t(4;21) case compared with CD34(+) cells that was independent of mutation or DNA methylation. More importantly, we explored and confirmed the possibility that this abrogation also prevented transactivation of RUNX1 target genes, perhaps confirming the genetic origin of the thrombocytopenia and the myelodysplastic features observed in our patient, and certainly mimicking what has been observed in the presence of the RUNX1/ETO fusion protein.engVoRhttp://creativecommons.org/licenses/by-nc-nd/4.0/AML1t(4;21)(q21;q22RUNX1 haploinsufficiencymegakariocytic lineage maturationAttribution-NonCommercial-NoDerivatives 4.0 International22102704974534-537HAEMATOLOGICAopen access