ESPE Abstracts

Introduction: Changes in thyroid function and thyroid function tests occur in patients with β-thalassemia major (TM). The frequency of hypothyroidism in TM patients ranges from 4% to 29 % in different reports. Bone marrow transplantation (BMT) is based on destruction of the patient’s bone marrow with rescue of haematopoietic stem cells from a donor. Chronic graft-vs-host disease (GVH) is the major complication post-BMT and mimics some autoimmune diseases, such as autoimmune hypothyroidism. We report a case of 7 years old boy with diagnosis of Major beta thalassemia in age of 3 months The parents are consangus and had one sister with heterozygote beta thalassemia. After two years of bone marrow transplantation the child presente a slow growth and symptoms of hypothyroidism confirmed by biological assays TSH 100 micro iu FT4 0.3 pmol/l anti thyroperoxidase antibody 307 ui/l and anti thyroglobuline antibody 1208 ui/l. These diseases occur mainly in association with chronic GVH. The pathophysiology of chronic GVH and other autoimmune-like diseases post-BMT remains poorly understood. Different mechanisms have been postulated. Most of the autoimmune events (either chronic GVH or more specific diseases) seem to be related to a poor or inadequate immunologic recovery post-BMT with an imbalance between autoregulatory and autoreactive lymphocytes. Microchimerism and molecular mimicry have been recently evocated. A minority of cases (autoimmune thyroid disorders) is attributed to the direct transfer of autoreactive cells from donor to patient (adoptive immunity). Despite physiopathologic uncertainty, these autoimmune-like disorders post-BMT are an interesting model for primary autoimmune diseases.