Abstract: The present invention relates to an isolated polynucleotide comprising from 5? to 3?: a first homology region, a splice acceptor sequence, a nucleotide sequence encoding a RAG1 polypeptide, and a second homology region for use in treating a RAG-deficient immunodeficiency.

Abstract: A method for selecting genome edited cells and/or for enrichment of genome edited cells in a population of cells comprising: (a) introducing into a cell or a population of cells at least one first component, at least one second component and at least one third component; and (b) selecting the genome edited cells which transiently express or transiently upregulate a nucleotide sequence encoding a selector.

Abstract: An agent which promotes homology directed DNA repair for use in haematopoietic stem and/or progenitor cell gene therapy, wherein said haematopoietic stem cells are gene edited. Use of an agent which promotes homology directed DNA repair, for increasing the survival and/or engraftment of gene edited haematopoietic stemand/or progenitorcells or for increasing the efficiency of gene editing of haematopoietic stem and/or progenitor cells.