This Unit major interests are in the field of hematopoietic stem cell biology and gene transfer to treat genetic diseases. Gene therapy is a therapeutic technique by which a functioning gene is inserted into the somatic cells of a patient to correct a genetic error or to provide a new function to the cell. Since 1989 we pioneered the use of retroviral vector-mediated gene transfer for gene therapy of human genetic diseases. Recently, we focused on transcriptional regulation of transgenes and molecular tools to provide persistence of gene expression in transduced stem cells. This is particularly relevant for gene therapy of blood disorders affecting red blood cells, such as hemoglobinopathies.