<qa>  What is the name of the study that will collect samples of blood, stool, bone mThis study will collect samples of blood, stool, bone marrow, or other tissues from patients with hepatitis-associated aplastic anemia to investigate a possible association between exposure to viruses and the development of aplastic anemia in these patients. Cells from the samples obtained may be grown in the laboratory for future studies. Patients samples may be used to: 