Investigating Cytokine Genes of Stem Cell Donors

This study seeks to investigate the factors that may account for the differences in the way a stem cell recipient s immune system works after a transplant. It will focus on cytokine genes, which give specific instructions to the genes and which may influence immune system response. More specifically, the purpose of the study is to find out how gene polymorphisms (gene variations among the population) affect the success or failure of a stem cell transplant. Study participants will have donated blood for a stem cell transplant. They will be asked to give consent for NIH personnel to run special tests on these blood samples, which will have been placed in storage. It is hoped that blood samples will be studied from 600 stem cell donors.