A novel mutation causing complete thyroxine-binding globulin deficiency (TBG-CD-Negev) among the Bedouins in southern Israel

T-4-binding globulin (TBG) is the major thyroid hormone transport protein i n human serum. Inherited TBG abnormalities do not usually alter the metabol ic status and are transmitted in X-linked inheritance. A high prevalence of complete TBG deficiency (TBG-CD) has been reported among the Bedouin popul ation in the Negev (southern Israel). In this study we report a novel singl e mutation causing complete TBG deficiency due to a deletion of the last ba se of codon 38 (exon 1), which led to a frame shift resulting in a prematur e stop at codon 51 and a presumed truncated peptide of 50 residues. This ne w variant of TBG (TBG-CD-Negev) was found among all of the patients studied . We conclude that a single mutation may account for TBG deficiency among t he Bedouins in the Negev. This report is the first to describe a mutation i n a population with an unusually high prevalence of TBG-CD.