Reduced Intensity Conditioning for Non-Malignant Disorders Undergoing UCBT, BMT or PBSCT

This study is testing a reduced-intensity preparation regimen before a bone marrow transplant (using a donor's stem cells) for children and adults with non-cancerous blood disorders, to see if a gentler approach can still be effective while reducing serious side effects. **You may be eligible if...** - You have been diagnosed with a non-cancerous blood or immune system disorder (such as sickle cell disease, thalassemia, bone marrow failure, or an immune deficiency) - A bone marrow or stem cell transplant from a matched donor has been recommended as your treatment - You are not healthy enough to tolerate the standard high-intensity transplant preparation - You have a suitable donor (related or unrelated, with a good tissue match) **You may NOT be eligible if...** - You have an active, uncontrolled infection - You have significant damage to your heart, liver, or kidneys - You have previously had a stem cell transplant that failed - You are pregnant - Your donor is not adequately matched Talk to your doctor to see if this trial is right for you.