Indeed chromosomal translocations such as AML1-ETO, PML-RARA and CBFβ-MYH11, which cause childhood Acute Myeloid Leukemia (AML), frequently arise in utero as demonstrated by the high prevalence of such mutations in neonatal blood samples [34–36], and may therefore impact fetal hematopoiesis. This evidence concerns the gene RUNX1 and acute myeloid leukemia.