Patients have a type of blood cell cancer, other blood disease or a genetic disease for which they will receive a stem cell transplant. The donor of the stem cells will be either a brother or sister or another relative or a closely matched unrelated donor. We are asking patients to participate in this study which tests if blood cells from the donor that have been grown in a special way, can prevent the patients from getting an infection with a virus called Cytomegalovirus or CMV.