Evaluation of Sickle Cell Liver Disease

Background: \- Sickle cell disease changes the shape of red cells. This makes them more likely to break down as they get stuck in small blood vessels. This leads to low red cell count and also damage to small blood vessels that supply many organs. One of the affected organs is the liver. Sickle cell disease and its treatment through blood transfusion can lead to significant liver damage. This disease also can cause the liver to regrow abnormally after damage. This can cause high blood pressure in the liver. Researchers want to know if curing sickle cell disease with a stem cell transplant improves liver damage. Objectives: \- To explore specific factors that improve or worsen sickle cell liver disease after a stem cell transplant. Eligibility: \- Adults ages 18 and older with sickle cell liver disease. Design: * Participation will take approximately 7 days over 2 years. * Visit 1: participants will be screened with medical history and review of current treatment regimen. * Visit 2: participants will return to the clinic for explanation of the study and physical exam. They will also have blood and urine tests, and scans of the liver. * All participants will have a 2-night stay at the clinic. They will have a liver biopsy and a test of liver pressure. They will be sedated and a tube will be inserted in a vein in their neck. * Participants who have a stem cell transplant will have a second biopsy about 24 months later. * Over the 2-year study period, participants will have blood drawn 2-4 times and stool samples collected 2 times.