Marina Cavazzana is a full Professor in Hematology at Paris-Cité University, the head of the Biotherapy Department at Necker Enfants Malades children’s hospital, and the coordinator of the Biotherapy Clinical Investigation Center at the Imagine Institute (Paris, France). Her basic and clinical research work and clinical activities are dedicated to the development and implementation of innovative treatments for monogenic disorders. She envisions that genetically engineered, patient-derived hematopoietic stem/progenitor cells (HSPCs) will constitute a transformative therapy and will overcome the obstacles posed by the non-availability of a human-leukocyte-antigen (HLA)-genoidentical family donor. In a proof-of-concept study in 2000 in collaboration with Professors Alain Fischer and Salima Hacein-Bey Marina Cavazzana demonstrated the clinical benefit of gene therapy by evidencing stable immunological reconstitution in two newborn boys with an X-linked severe combined immunodeficiency (SCID-X1).