Transmission of thyrotoxicosis of autoimmune type by sibling allogeneic bone marrow transplant

This case report is on a 25-year-old male with acute myeloblastic leukaemia who achieved a remission after cytoxic therapy and whole-body irradiation. He received a bone marrow transplant from his human leucocyte antigen (HLA)-identical sister who had unsuspected autoimmune thyroid disease. Nine months later the bone marrow recipient developed thyrotoxicosis of autoimmune type at a time when his circulating lymphocytes were of 46XX karyotype. It is suspected that the thyrotoxicosis resulted from the transplantation of a clone of lymphocytes predisposed to the production of thyroid-stimulating autoantibodies.