The TET1 gene, was initially identified in acute myeloid leukemia (AML) as a fusion partner of the histone H3 Lys 4 (H3K4) methyltransferase MLL (mixed-lineage leukemia) (Ono et al. 2002; Lorsbach et al. 2003). TET1 is significantly upregulated and plays an oncogenic role in MLL-rearranged leukemia, rendering TET1 as a potential target for treating this form of hematopoietic malignancy ( Huang et al., 2013). Tet1 is abundantly expressed in hematopoietic stem/progenitor cells (HSC/HPCs) and differentiated lineages such as B cells and myeloid cells (Huang et al., 2013; Li et al., 2011 ; Moran-Crusio et al., 2011)