Visser Theo J
Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
Horm Res. 2007;68 Suppl 5:28-30. doi: 10.1159/000110469. Epub 2007 Dec 10.
Cellular uptake and release of thyroid hormone are mediated by transporters. Among these, monocarboxylate transporter 8 (MCT8) shows particularly high activity towards the active thyroid hormone 3,3',5-triiodothyronine (T(3)). MCT8 is expressed in different tissues, including the brain where it is predominantly localized in neurons. The MCT8 gene is located on the X chromosome.
Mutations in MCT8 have been identified in boys with severe psychomotor retardation who also have very high serum T(3) levels. Thyroid hormone is crucial for brain development, and mutations in MCT8 prevent the access of T(3) to its main target cells. Thus, mutations in MCT8 represent a novel mechanism for the pathogenesis of thyroid hormone resistance.
甲状腺激素的细胞摄取和释放由转运体介导。其中，单羧酸转运体8（MCT8）对活性甲状腺激素3,3',5-三碘甲状腺原氨酸（T(3)）表现出特别高的活性。MCT8在不同组织中表达，包括大脑，在大脑中它主要定位于神经元。MCT8基因位于X染色体上。
在患有严重精神运动发育迟缓且血清T(3)水平非常高的男孩中已鉴定出MCT8突变。甲状腺激素对大脑发育至关重要，MCT8突变会阻止T(3)进入其主要靶细胞。因此，MCT8突变代表了甲状腺激素抵抗发病机制的一种新机制。
