DiGeorge anomaly is a complex of cardiac defects, parathyroid deficiency, and thymus absence, resulting in profound T-cell deficiency. There is a spectrum of disease in DiGeorge anomaly with respect to all three defects. For complete DiGeorge anomaly subjects with severe T cell defect, the PI had shown that thymus transplantation is safe and efficacious without pretransplantation immunosuppression and with pretransplantation Thymoglobulin and cyclosporine.