A Single Nucleotide Deletion resulting in Frameshift in Two Korean Neonates with Thyroxine-Binding Globulin Deficiency / 소아과

ABSTRACT

Abnormalities in the levels of thyroxine-binding globulin (TBG) are not associated with clinical disease and they do not require treatment. Congenital TBG deficiency is inherited in an X-linked manner. To date, some complete and partial TBG variants and one polymorphism have been identified by analysis of the TBG gene. Two male neonates were referred to us because of their low T4 levels that were noted on the neonatal screening test. They showed normal levels of free T4 and TSH. Their serum TBG was not detectable and those values of their parents were within the normal ranges. The genomic DNA was extracted from their white blood cells and the four coding exons of the TBG gene were amplified by using polymerase chain reaction. Sequencing of the four coding regions and all the intron/exon junctions revealed a single nucleotide deletion of the first base of the codon 352 of the mature protein in both of the neonates. This mutation resulted in a frameshift and a premature stop codon (TGA) 374. Their mothers were shown to be heterozygotes. We detected a single nucleotide deletion resulting in a frameshift in two male Korean neonates who had complete TBG deficiency.