Fetal hemoglobin-a type of hemoglobin that is produced during fetal and infant life-can substitute for adult hemoglobin and increase the levels of red cells in the body. After infancy, however, this type of hemoglobin is no longer produced in large quantities. 5-azacytidine can increase fetal hemoglobin levels, but this drug can damage DNA, which in turn can increase the risk of cancer. This study will try to lessen the harmful effects of 5-azacytidine by using only one or two doses of it, followed by long-term therapy with phenylbutyrate, a drug that may be as effective as 5-azacytidine with less harmful side effects.