Response-Based Chemotherapy in Treating Newly Diagnosed Acute Myeloid Leukemia or Myelodysplastic Syndrome in Younger Patients With Down Syndrome

Inclusion Criteria:

   - Patients must have constitutional trisomy 21 (Down syndrome) or trisomy 21 mosaicism
   (by karyotype or fluorescence in situ hybridization [FISH])

   - Patient has one of the following:

      - Patient has previously untreated de novo AML and meets the criteria for AML with
      >= 20% bone marrow blasts as set out in the World Health Organization (WHO)
      Myeloid Neoplasm classification

         - Attempts to obtain bone marrow either by aspirate or biopsy must be made
         unless clinically prohibitive; in cases where it is clinically prohibitive,
         peripheral blood with an excess of 20% blasts and in which adequate flow
         cytometric and cytogenetics/FISH testing is feasible can be substituted for
         the marrow exam at diagnosis

      - Patient has cytopenias and/or bone marrow blasts but does not meet the criteria
      for the diagnosis of AML (WHO Myeloid Neoplasm classification) because of < 20%
      marrow blasts and meets the criteria for a diagnosis of myelodysplastic syndrome
      (MDS)

      - For patients who do not meet criteria for AML or MDS as outlined above; patient
      has a history of transient myeloproliferative disorder (which may or may not have
      required chemotherapy intervention and:

         - Is > 8 weeks since resolution of transient myeloproliferative disease (TMD)
         with >= 5% blasts, OR

         - Has an increasing blast count (>= 5%) in serial bone marrow aspirates
         performed at least 4 weeks apart

   - Children who have previously received chemotherapy, radiation therapy or any
   anti-leukemic therapy are not eligible for this protocol, with the exception of
   cytarabine for the treatment of TMD

   - There are no minimal organ function requirements for enrollment on this study

      - Note: Previous cardiac repair with sufficient cardiac function is not an
      exclusion criteria

   - Each patient's parents or legal guardians must sign a written informed consent

   - All institutional, Food and Drug Administration (FDA), and National Cancer Institute
   (NCI) requirements for human subjects research must be met

Exclusion Criteria:

   - Patients with promyelocytic leukemia (French-American-British [FAB] M3)

   - Prior therapy

      - Patients =< 30 days from the last dose of cytarabine used for treatment of TMD