Decitabine for Myelodysplastic Syndromes and Acute Myeloid Leukemia Before Allogeneic Hematopoietic Cell Transplantation

Inclusion Criteria: * Age 8- 65 years * Diseases must be myelodysplastic syndrome and acute myelocytic leukemia * Must need a bone marrow transplant * Must have the ability to observe the efficacy and events * Patient must have ability to understand and willingness to provide written informed consent prior to participation in the study and any related procedures being performed Exclusion Criteria: * Must not have uncontrolled intercurrent illness including ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, or psychiatric illness/social situations that would limit compliance with study requirements * Must not be pregnant or breastfeeding; pregnant women are excluded from this study because decitabine is a Category D agent with the potential for teratogenic or abortifacient effects; because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with decitabine, breastfeeding should be discontinued if the mother is treated with decitabine; these potential risks may also apply to other agents used in this study * Must not have a known or suspected hypersensitivity to decitabine