[Thyroid-stimulating hormone receptor and thyroid diseases]

Since the description of the structure of the TSH receptor using molecular biology techniques, it has become possible to analyse the role of anomalies of this receptor in thyroid disorders. Implicated in the pathophysiology of Graves' disease by indirect observations, the autoantigenic role of the TSH receptor has now been clearly confirmed. Nevertheless, the epitopes of the extracellular domain of the receptor corresponding to each type, stimulatory or epitopes of the extracellular domain of the receptor corresponding to each type, stimulatory or blocking, of anti-receptor toward activation or blocking. The events that induce and maintain autoimmunization to the receptor remain hypothetical, but the possible existence of soluble forms of the receptor opens new perspectives. In practice, however, assessment of TSH anti-receptor antibodies is useful in managing Graves' disease and in certain cases of primary myxoedema linked to the presence of blocking antibodies; it is mandatory in pregnant women for detection of foetal disease induced by maternal antibodies. The responsibility of the receptor is sought in other thyroid diseases such as toxic adenoma, rare forms of nonimmunologic, familial hyperthyroidism, simple goiter, nodules and lack of response to TSH. Recently, a mutation mapped into the 3rd intracellular loop has been shown in toxic adenoma. Such discoveries are as important for physicians (and patients) as for cellular biologists.