Allogeneic Hematopoietic Stem Cell Transplantation

To assess the engraftment of hematopoietic stem cells following reduced-intensity conditioning in children presenting with solid tumors or hematological malignancy by evaluating post-transplantation chimerism and hematological reconstitution. To study acute and/or chronic graft-versus-host reaction (incidence and severity) and immune reconstitution, post-transplantation To study the effectiveness of the protocol on tumor response. To study overall survival.