Combination Chemotherapy With or Without Gemtuzumab in Treating Young Patients With Newly Diagnosed Acute Myeloid Leukemia

DISEASE CHARACTERISTICS: * Newly diagnosed acute myeloid leukemia (AML) * Meets customary criteria for AML with ≥ 20% bone marrow blasts (by WHO classification) * Patients with \< 20% bone marrow blasts and cytopenia or myelodysplastic syndromes (e.g., chronic myelomonocytic leukemia, refractory anemia (RA), RA with excess blasts, RA with ringed sideroblasts) are eligible provided 1 of the following criteria is met: * Karyotypic abnormality characteristic of de novo AML (t\[8;21\]\[q22;q22\], inv\[16\]\[p13q22\], t\[16;16\]\[p13;q22\], or 11q23 abnormalities) * Unequivocal presence of megakaryoblasts (by WHO classification) * Isolated myeloid sarcoma (i.e., myeloblastoma or chloroma) allowed regardless of bone marrow results * Infants \< 1 month of age with progressive disease\* are eligible NOTE: \*Infants \< 1 month of age with AML may be given supportive care until it is clear that the leukemia is not regressing (i.e., the disappearance of peripheral blasts and the normalization of peripheral blood counts) * Patients with Down syndrome ≥ 4 years of age are eligible * No juvenile myelomonocytic leukemia * No Fanconi's anemia, Kostmann syndrome, Shwachman syndrome, or any other known bone marrow failure syndrome * No promyelocytic leukemia (M3) * No secondary or treatment-related AML * Matched family donor criteria (for patients with intermediate-risk or high-risk disease): * HLA-A, -B, -C, and beta chain (-DRB1), identical or 1 antigen or allele m…