Combination Chemotherapy and Donor Stem Cell Transplant in Treating Patients With Aplastic Anemia or Hematologic Cancer

DISEASE CHARACTERISTICS: * Diagnosis of one of the following: * Severe aplastic anemia as defined by either of the following: * Marrow cellularity (\< 25% \[or 25-50% cellularity with \< 30% of remaining cells hematopoietic in origin\]) * At least 2 of the following abnormal peripheral blood counts: * Reticulocyte count \< 1% (corrected for hematocrit) * Platelet count \< 20,000/mm\^3 * Neutrophil count \< 500/mm\^3 * Histologically confirmed hematologic malignancy, including any of the following: * Acute leukemia * Resistant or recurrent disease after combination chemotherapy with at least one standard regimen OR in first remission and at high risk of relapse * Acute myeloid leukemia (AML) (antecedent myelodysplastic syndromes \[MDS\], secondary AML, or high-risk cytogenetic abnormalities) * Acute lymphoblastic leukemia (ALL) (high-risk cytogenetic abnormalities) * Chronic myeloid leukemia (CML) * Chronic phase, accelerated phase, or blast phase * Myeloproliferative disorders or MDS, including any of the following: * Myelofibrosis * Polycythemia vera\* * Essential thrombocythemia\* * Refractory anemia * Refractory anemia with excess blasts * Refractory anemia with excess blasts in transformation * Chronic myelomonocytic leukemia NOTE: \* Only if transformed to AML or MDS * Lymphoproliferative disease * Recurrent or persistent, symptomatic disease aft…