Patients will be monitored with blood tests daily for 2 weeks and then will be seen weekly for about another 5 weeks. Bone marrow biopsies will be repeated 6 days after treatment begins and again at 2 weeks and 7 weeks. MRI will be repeated 7 weeks after treatment begins. After 7 weeks, patients will be seen at 3-month intervals. Bone marrow biopsies will be done every 6 months for the first 3 years after treatment. Patients will have red cell transfusions as needed and chelation therapy to remove excess iron.