Mr. r married a healthy woman in his home country of italy and had three children, a boy with beta-thalassemia minor and two healthy girls. then, after the death of his wife, mr. r immigrated to the united states, where he married a woman who has beta-thalassemia major. both of her beta-chain genes are abnormal, but her disease was medically controlled with transfusions and chelation, a treatment to remove excess iron from the body. she has been looking into the possibility of a bone marrow transplant. why would a bone marrow transplant someone whose red blood cells had a genetic defect?