Inclusion Criteria

DISEASE CHARACTERISTICS:

- Cytogenetically proven Down Syndrome (constitutional trisomy 21) with transient
myeloproliferative disorder (TMD), myelodysplastic syndromes (MDS), or acute
myelogenous leukemia (AML)

- Must be confirmed by bone marrow aspirate, cerebrospinal fluid exam, or blood
test

- Trisomy 21 mosaicism allowed

- Group I:

- Diagnosis of TMD in patients no older than 90 days at initial presentation

- Must have nonerythroid blasts (any amount) in the peripheral blood and one of
the following:

- Verification with a second sample

- More than 5% bone marrow blasts

- Hepatomegaly and/or splenomegaly

- Lymphadenopathy

- Cardiac or pleural effusions OR

- Histologically or cytologically proven TMD with blasts in an affected organ or
in fluid (pericardial, pleural, or peritoneal)

- Bone marrow aspirate is required

- Group II (closed to accrual as of 6/24/04):

- Diagnosis of MDS or AML (except M3 subtype) in patients older than 90 days with
more than 29% blasts in bone marrow (with or without history of TMD), or any of
the following histologies:

- Refractory anemia (RA)

- RA with excess blasts (RAEB)

- RAEB in transformation

- RA with ringed sideroblasts (RARS)

- Primary cytopenia (later confirmed by bone marrow aspirate as due to marrow
hypoplasia) defined by one or more of the following:

- Absolute neutrophil count less than 500/mm^3

- Untransfused platelet count less than 30,000/mm^3

- Untransfused hemoglobin less than 8 g/dL

- The following diagnoses will be observed only:

- RA with mild cytopenias*

- RARS with mild cytopenias*

- Mild primary cytopenias (one or more) without dysplasia (confirmed by
hypoplastic bone marrow exam) NOTE: * Platelet count 30-150,000/mm3, absolute
neutrophil count 500-1,499/mm3, and hemoglobin greater than 8 g/dL

- Granulocytic sarcoma (chloroma), with or without bone marrow involvement, allowed

PATIENT CHARACTERISTICS:

Age:

- See Disease Characteristics

- 21 and under

Performance status:

- Not specified

Life expectancy:

- Not specified

Hematopoietic:

- See Disease Characteristics

Hepatic:

- See Disease Characteristics

Renal:

- Not specified

Cardiovascular:

- Shortening fraction greater than 27% by echocardiogram* OR

- Ejection fraction greater than 47% by radionuclide angiogram* NOTE: *For patients
with MDS and AML (as of 2/24/04, previously diagnosed MDS or AML closed to accrual;
MDS or AML that develops (secondary to TMD) after study enrollment or MDS that
requires initial observation [with or without subsequent treatment] allowed)

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- Not specified

Chemotherapy:

- Prior chemotherapy for TMD allowed

- No prior chemotherapy for malignancy

Endocrine therapy:

- Concurrent topical or inhaled steroids for other conditions allowed

Radiotherapy:

- No prior radiotherapy for malignancy

Surgery:

- Not specified

Other:

- No prior antileukemic therapy

- Prior enrollment on this study for TMD allowed