For the TNF promoter polymorphism at position −1031(T/C), we observed a significant increase in the frequency of the rarer TNF −1031C allele in the PTLD subject group compared with the non-PTLD transplant control group (37% vs 19%; P=0.005; Figure 1A;, Table 1) and when compared with the healthy control group (37% vs 23%; P=0.01; Table 1). Here, TNF is linked to post-transplant lymphoproliferative disease.