Furthermore, we summarize the treatment modalities and outcomes of these patients and review in detail the course of one of them who was successfully treated with serial, unconditioned, maternal, HLA-identical donor lymphocyte infusions (DLI) against life-threatening, invasive CMV infection, followed by a TCRαβ/CD19-depleted, treosulfan/melphalan-conditioned, peripheral blood HSCT and repetitive, secondary-prophylactic, CMV-specific DLI with 1-year post-HSCT follow-up. This evidence concerns the gene CD19 and cytomegalovirus infection.