[Inherited abnormality of thyroxine-binding globulin: its gene abnormality and pathogenesis]

Inherited TBG abnormalities manifest complete deficiency (CD), partial deficiency (PD) or excess in blood. Analysis of the TBG gene revealed that all cases with CD and PD studied so far had mutations within the exon. A nucleotide substitution was found in each case of PD and one of three cases of CD. In two other cases of CD, there was a nucleotide deletion. By the transfection study, it was revealed that TBG-CD secretion was completely blocked due to an impaired transport from rough endoplasmic reticulum to Golgi apparatus. The cause of PD is also explained by a partial impairment of TBG secretion. However, a pathogenesis of TBG excess has not been clarified yet.