Conditioning regimens for PID recommended by EBMT/ESID inborn errors working party [14]. Protocol A and B: These are recommended for patients without severe preexisting organ damage and non-SCID diseases where a complete donor chimerism is desired for optimal disease correction. Protocols C and D: These are recommended for patients with preexisting organ damage and/or diseases where engraftment has been shown to reliably occur with reduced intensity conditioning. Mixed donor chimerism is more likely to occur compared to protocols A and B. Protocol E: This may be best suited for patients with preexisting organ damage and/or diseases where full myeloid engraftment is not absolutely required. Higher degrees of chimerism can be achieved when using PBSC. DLI may be required in case of mixed chimerism. Protocol F: To avoid organ toxicity this regimen is only recommended for patients with DNA repair/radio-sensitivity disorders (except Artemis deficiency) in which alkylating agents are used in low dose. PID, primary immune deficiencies; EBMT, European Society for Blood and Marrow Transplantation; ESID, European Society for Immune Deficiencies; SCID, severe combined immunodeficiency; PBSC, peripheral blood stem cell; DLI, donor lymphocyte infusion.