Congenital hypothyroidism: Searching for its genetic basis

Congenital hypothyroidism is characterized by reduced thyroid hormone levels produced by the follicular cells of the thyroid gland in response to elevated levels of the thyroid stimulating hormone. In the great majority of the cases, congenital hypothyroidism is a consequence of thyroid dysgenesis (TD). Recently, it has been demonstrated that mutations in genes involved in the differentiation process of thyroid follicular cells cause, both in humans and in mouse models, alterations in the formation of the thyroid gland during embryogenesis (TD). The pathogenesis of TD is still largely unknown, although a genetic component has been suggested. The data presented in this review clearly underline that TD is a complex disease. However, they provide the first evidence in favor of the existence of a genetic basis of this condition.