Mixed chimerism after bone marrow transplantation for thalassemia major.

Thirty-four thalassemia patients were studied for chimerism by fluorescent in situ hybridization or variable number tandem repeats after bone marrow transplantation. Mixed chimerism was detected in 9 patients with host cells ranging from 4 to 56%. One had graft rejection and the others were transfusion independent. Mixed chimerism was common but mostly without deleterious effect.