Combination Chemotherapy Followed by Donor Bone Marrow Transplant or Peripheral Stem Cell Transplant in Treating Patients With Hematologic Cancer or Genetic Disorders

DISEASE CHARACTERISTICS: * Clinically and/or histologically confirmed hematologic malignancy or genetic disorder * Chronic myelogenous leukemia * Typical blood and marrow morphology * Presence of Philadelphia chromosome OR * Molecular evidence of bcr/abl rearrangement if Philadelphia chromosome-negative * Acute myeloid leukemia, acute lymphocytic leukemia, myelodysplasia, or lymphoma * High risk of relapse or progressive disease * Typical clinical features and morphology in blood, marrow, lymph node, or other tissue by cytochemistry, immunophenotyping, and/or chromosomal abnormalities * Multiple myeloma * Typical marrow morphology, radiographic findings, and paraprotein * Aplastic anemia * Typical marrow and blood findings * Genetic disorder including storage disease (e.g., adrenoleukodystrophy), hemoglobinopathies (e.g., thalassemia), or severe immunodeficiency * Unwilling to undergo conventional high-dose chemoradiotherapeutic conditioning prior to allogeneic stem cell transplantation OR * Presence of other medical disorder which precludes high-dose chemoradiotherapeutic conditioning (e.g., cardiac disease or infection) * Syngeneic twin, HLA-identical, or 1 or 2 HLA antigen-mismatched family member or unrelated donor PATIENT CHARACTERISTICS: Age: * 1 to 80 Performance status: * Karnofsky 50-100% Life expectancy: * Not specified Hematopoietic: * Not specified Hepatic: * Not specified Renal: * Not specified Other: * N…