A poor CD8 recovery has been described following HLA-mismatched thymic transplantation in DiGeorge syndrome [12], [13], possibly related to the full HLA class I mismatch between host hematopoietic precursors and allogeneic thymic epithelia or to alterations in the thymic graft associated with transplantation procedures. The gene discussed is CD8A; the disease is 22q11.2 deletion syndrome.