GABBR1 and graft versus host disease: The frequency of II-IV acute GVHD, according to CMV gB genotype, showed that 8 out of 19 gB1 patients (42%), 1 out of 17 gB2 patients (6%), 3 out of 7 gB4 patients (43%) had aGVHD, and all 4 gB3 patients, including the mixture gB1 + gB3, had aGVHD (P = 0.008).