Bone marrow transplantation from identical twins in the treatment of aplastic anaemia: implication for the pathogenesis of the disease.

Treatment of aplastic anaemia by bone marrow transplantation from a syngeneic (identical twin) donor has provided insights into the pathophysiology of the disease. We report from patients with severe anaemia who were treated by syngeneic bone marrow transplantation. None of the patients had sustained recovery of peripheral blood counts. All four received second transplants from the same twin donor after immunosuppressive conditioning treatment. Each had prompt recovery of haematopoiesis. A review of the literature indicates that failure of syngeneic bone marrow transplantation in patients with aplastic anaemia is not uncommon. These data indicate that aplastic anaemia may be caused by a mechanism other than an absence or intrinsic abnormality of haematopoietic stem cells in many patients.