Donor Bone Marrow Transplant With or Without G-CSF in Treating Young Patients With Hematologic Cancer or Other Diseases

Inclusion Criteria:

* Diagnosis of hematologic cancer or other disease, including any of the following:

  * Chronic myelogenous leukemia in first or second chronic phase
  * Acute lymphoblastic leukemia (ALL), meeting any of the following criteria:

    * Relapsed ALL enrolled on a Children's Oncology Group (COG) relapse clinical trial OR received ≥ 1 round of reinduction therapy (4-6 weeks) and 1 round of intensive consolidation chemotherapy (3-6 weeks)
    * ALL in second complete remission (CR)\* after a bone marrow, extramedullary, or combined bone marrow and extramedullary relapse
    * Very high-risk ALL in first CR, defined as any of the following:

      * Philadelphia chromosome-positive ALL
      * Hypodiploidy (\< 44 chromosomes)
      * Mixed lineage leukemia rearrangement
      * Induction failure
  * Acute myeloid leukemia in first or second CR

    * Induction therapy must be completed
  * Juvenile myelomonocytic leukemia
  * Myelodysplastic syndromes
* No clinically evident CNS or extramedullary disease
* No blasts seen on cerebrospinal fluid cytospin
* Post-relapse reinduction therapy must be completed
* Not planning to receive reduced-intensity conditioning regimen
* Not planning to receive a graft that has undergone T-cell depletion
* No Down syndrome
* Matched sibling donor must be available and must be enrolled on ASCT0631D companion study
* Karnofsky performance status (PS) 60-100% (patients \> 16 years of age) OR Lansky PS 60-100% (patients ≤ 16 years of age)
* AST or ALT \< 5 times upper limit of normal for age
* Bilirubin \< 2.5 mg/dL (unless due to Gilbert's syndrome)
* Creatinine clearance or radioisotope glomerular filtration rate ≥ 70 mL/min OR serum creatinine base on age and/or gender as follows:

  * 0.4 mg/dL (1 month to \< 6 months of age)
  * 0.5 mg/dL (6 months to \< 1 year of age)
  * 0.6 mg/dL (1 to 2 years of age)
  * 0.8 mg/dL (2 to \< 6 years of age)
  * 1.0 mg/dL (6 to \< 10 years of age)
  * 1.2 mg/dL (10 to \< 13 years of age)
  * 1.5 mg/dL (male) or 1.4 mg/dL (female) (13 to \< 16 years of age)
  * 1.7 mg/dL (male) or 1.4 mg/dL (female) (≥ 16 years of age)
* Shortening fraction ≥ 27% by echocardiogram OR LVEF ≥ 50% by radionuclide angiogram
* FEV\_1, FVC, and DLCO ≥ 60% OR meets the following criteria (for patients unable to cooperate for pulmonary function tests):

  * No evidence of dyspnea at rest
  * No exercise intolerance
  * No requirement for supplemental oxygen therapy
* Not pregnant or nursing
* No known HIV
* No known uncontrolled fungal, bacterial, or viral infections

  * Patients acquiring fungal disease during induction therapy may proceed if they have a significant response to antifungal therapy with no or minimal evidence of disease remaining by CT scan
* No prior allogeneic or autologous stem cell transplantation