Reduction of blood group A antigen on erythrocytes in a patient with myelodysplastic syndrome harboring somatic mutations in RUNX1 and GATA2

Abstract

Background: Reduction of blood group ABO antigens on red blood cells (RBCs) is well known in patients with leukemias, and this reduction of ABO expression is strongly associated with DNA methylation of the ABO promoter.Previously, we reported a two-nucleotide deletion in RUNX1 encoding an abnormally elongated protein lacking the trans-activation domain in a patient with myelodysplastic syndrome (MDS) showing A-antigen loss on RBCs. This prompted us to investigate the underlying mechanism responsible for A-antigen reduction on RBCs in another patient with MDS.Study Design and Methods: Screening of somatic mutations was carried out using a targeted sequencing panel with genomic DNA from peripheral blood mononuclear cells from the patient and eleven MDS controls without A-or Bantigen loss. DNA methylation of the ABO promoter was examined by bisulfite genomic sequencing. Transient transfection assays were performed for functional evaluation of mutations.Results: Screening of somatic mutations showed missense mutations in RUNX1 and GATA2 in the patient, while no mutation was found in exons of those genes in the controls. There was no significant difference in ABO promoter methylation between the patient and the controls. Transient transfection experiments into COS-7 and K562 cells suggested that the amino acid substitutions encoded by those mutations reduced or lost the trans-activation potential of the ABO expression. Conclusion: Considering the discrepancy between the variant frequencies of these mutations and the ratios of the RBCs with A-antigens loss, the antigen reduction might be associated with these somatic mutations and hypermethylation of the ABO promoter.COSMIC with accession numbers: COSP49519.

CEBPA double mutations associated with ABO antigen weakness in hematologic diseases

“…Among these, 145 patients had malignancies, of which 103 were diagnosed with hematologic diseases. Genetic analysis of patients with hematologic diseases revealed not only the previously reported gene RUNX1 10 , 11 but also previously unidentified genes, CEBPA , NRAS , U2AF1 , and PTPN11 , all potentially associated with this phenomenon.…”

“… 15 , 16 In addition, other genes known to be involved in ABO gene expression were also investigated, and mutations of RUNX1 and GATA2 were suggested to be related with the reduction of erythrocyte A antigen expression. 10 , 11 RUNX1 encodes a Runt-related transcription factor, which plays a role in regulation of hematopoiesis. 17 RUNX1 is one of the frequently mutated genes in myeloid malignancies.…”

“… 19 Although the mechanism was not clarified, the presence of a GATA2 pathogenic variant in patients with AML with reduced A antigen expression suggests that GATA2 is implicated as a potential cause of antigenic attenuation. 11 Although previous studies suggested the potential involvement of RUNX1 and GATA2 variants in weakening ABO antigen expression, the evidence for this association remains limited to a few cases and simple in vitro assays using cell lines. A recent study investigating the association of RUNX1 and GATA2 with this phenomenon among patients with AML found no significant correlation between these genes and ABO antigen weakness.…”

“…Mutations of genes involved in hematopoiesis, which were frequently detected in those patients, have been suspected as causes of the phenomenon. 10 , 11 …”

ABO Blood Group Antigen Changes in Acute Myeloid Leukemia and No Significant Association WithRUNX1andGATA2Somatic Variants

“…GATA-binding protein 2 (GATA2) genes encode transcription factors that bind to specific ABO motifs [3]. The +5.8-kb site in intron 1 of ABO includes one recognition motif for the RUNX1 protein and two motifs for the GATA2 protein [4]. Associations with somatic variants of genes such as RUNX1 and GATA2 have been studied; however, their relationship has not yet been validated in clinical samples [4,5].…”