This is a multi-center, long-term safety and efficacy follow-up study for subjects with
hemoglobinopathies (β-thalassemia or severe sickle cell disease) who have been treated with
ex vivo gene therapy drug product in bluebird bio-sponsored clinical studies. After
completing the parent clinical study (approximately 2 years), eligible subjects will be
followed for an additional 13 years for a total of 15 years post-drug product infusion. No
investigational drug product will be administered in the study.