A STUDY OF THE ASSOCIATION BETWEEN A POLYMORPHISM IN THE CTLA-4 GENE AND POSTPARTUM THYROIDITIS

OBJECTIVE Postpartum thyroiditis (PPT) is an autoimmune thyroid diseas e which shares immunological and clinical features with autoimmune hyp othyroidism and Graves' disease, and is believed to be caused by a com bination of genetic and environmental factors. Recently, an associatio n has been described between Graves' disease or autoimmune hypothyroid ism and a polymorphism in the CTLA-4 gene, which encodes a T cell rece ptor for the B7 family of ligands, and we wished to test whether a sim ilar association exists with PPT, DESIGN A population-based case-contr ol study of a CTLA-4 gene microsatellite polymorphism was performed, t o look for an association with PPT, PATIENTS Caucasoid women (n=122) w ere studied; 58 had thyroid antibodies (against thyroglobulin or thyro id peroxidase) alone during the postpartum period (PPT-) and 64 had th yroid antibodies and some form of postpartum thyroid dysfunction (PPT), RESULTS There was no significant difference between this whole grou p of women and 161 local Caucasoid thyroid antibody-negative women for the CTLA-4106 base pair (AT), microsatellite polymorphism (relative r isk = 1.3; P=0.3), nor did the PPT+ group differ from controls when an alysed separately (P=0.2). When the postpartum women were subdivided i n groups according to clinical pattern of PPT and the type of thyroid antibodies, there were no associations within the subgroups, CONCLUSIO NS No significant association exists between postpartum thyroiditis an d a polymorphism in the CTLA-4 gene. Furthermore, a natural variation in the prevalence of the polymorphism in healthy UK populations unders cores the need to select appropriately matched normal subjects in futu re case-control studies.