A number of observations also suggest that although RUNX1 is involved in the first steps of leukemia development, additional somatic mutations are necessary and probably determinant for the leukemic phenotype: 1) The predisposition to develop leukemia in FPD-AML patients shows that germline RUNX1 mutations are not sufficient for the development of the disease [10]. This evidence concerns the gene RUNX1 and acute myeloid leukemia.