Diagnoses included precursor cell lymphoblastic leukemia, not otherwise specified (NOS, n = 19), B-lymphoblastic leukemia/lymphoma, NOS (n = 14), precursor B-cell lymphoblastic leukemia (n = 7), T-lymphoblastic leukemia/lymphoma (n = 2), and leukemia/lymphoma with t(12;21)(p13;q22);TEL-AML1(ETV6-RUNX1) (n = 1). This evidence concerns the gene RUNX1 and leukemia.