There were no significant differences between the patients with PT and the controls (P > .05) with regard to the demographic and clinical characteristics, including age, sex, underlying disease, disease status before transplantation, donor types, source of stem cells, transplanted total nucleated cell dose, CD34+ cell dose, conditioning regimen, history of GvHD, history of CMV reactivation, and anti-CMV therapy (Table 1). This evidence concerns the gene CD34 and graft versus host disease.