The low producer interferon gamma (IFN-γ) genotype has been implicated in EBV reactivation after stem cell transplantation and with the development of PTLD after renal and liver transplantation (VanBuskirk et al, 2001; Bogunia-Kubik et al, 2006; Lee et al, 2006). Here, IFNG is linked to post-transplant lymphoproliferative disease.