A novel mutation (del 1711 G) in the TBG gene as a cause of complete TBG deficiency.
OBJECTIVE
Inherited thyroxine-binding globulin (TBG) deficiency is caused by mutations in the TBG gene (locus: Xq22.2), which result in defective synthesis or changes in the physical properties or biological function of a protein.


METHODS
We report a novel mutation of the TBG gene causing a complete TBG deficiency in three brothers of Polish origin. DNA was extracted from all of the family members and subjected to sequence analysis. We analyzed the family with a heterozygous mother, a normal father, their three hemizygous affected sons, and their two normal sons.


RESULTS
Our studies revealed a novel mutation, a single nucleotide deletion (guanine) at position 1711, codon 201 (Asp) in exon 2 (GAC --> AC). This mutation led to a frame shift and premature termination at codon 206, causing a short TBG protein of 205 amino acids (AA) compared to 395 AA of the normal TBG. This new TBG-CD variant was found in the mother and her three affected sons.


CONCLUSIONS
This is a new variant of TBG-CD (TBG-CD-PL Poland) containing 205 AA.
Lacka
Katarzyna
K
Department of Endocrinology, University of Medical Sciences, Przybyszewski Str. 49, Poznan, Poland. k_lacka@wp.pl
Nizankowska
Teresa
T
Ogrodowicz
Agnieszka
A
Lacki
Jan K
JK
D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D017384:Sequence Deletion; D013975:Thyroxine-Binding Proteins / Q000172:deficiency* / Q000235:genetics*
D013975:Thyroxine-Binding Proteins