46 HIGH FREQUENCY OF GATA2 MUTATIONS IN APLASTIC ANEMIA AND HYPOCELLULAR MYELODYSPLASTIC SYNDROME

Abstract

were transplanted into recipients. 4 weeks post-transplantation, we treated mice with either 0, 0.5 or 2Gy radiation. Mice were monitored for aberrations in any of the hematopoietic lineages in both peripheral blood (PB) and bone marrow (BM) at frequent intervals. Mice developing t-MDS/AML like disease were sacrificed and ligation-mediated PCR (LM-PCR) was performed to identify the integration sites. Results: Ranging from 23-59 weeks post-radiation, 70% of the animals treated with 0.5Gy developed a tMDS/AML-like disease while interestingly only 17% of the 2Gy mice developed tMDS/ AML-like disease. None of the control animals developed tMDS/ AML-like disease, confirming specificity for t-MDS of our experimental setup. BM of mice with tMDS/AML-like disease showed a high level of donor chimerism and mice exhibited anemia, thrombocytopenia, splenomegaly and myeloid blasts in BM at different time points. In LM-PCR, we observed unique band patterns for each of the t-MDS/AML mice, indicating that the clones driving the disease were probably unique. Further gene expression analysis was performed on the genes located around the integration site to identify individual genes that are altered in these mice. Among others, C1q and tumor necrosis factor related protein 6 (c1qtnf6/ CTRP6), a fatty acid oxidation regulatory gene, Neuroblastoma ras oncogene (N-ras), a known oncogene in various cancers and miR10a, a microRNA regulating cell survival through Twist1 gene expression in myeloid cells, are the genes with altered expression in tMDS/AML mice. Thus generated presumptive t-MDS predisposing gene list further needs to be validated in vivo. Future directions: We anticipate a detailed validation of these genes in mice will facilitate the identification of genes that predispose to t-MDS/AML. We believe this is a unique mouse model mimicking a radiation mediated tMDS clinical scenario.