The rate of rejection/thalassemia recurrence was much higher in
thalassemic patients than in patients transplanted because of malignancies.
Several factors have been invoked to explain this difference:
massive pretransplant exposure to blood products, not having
received any chemotherapy before transplant, expanded erythropoietic
marrow, and possibly splenomegaly. Interestingly, the phenomenon
of high thalassemia recurrence was limited to patients younger
than age 17.