First report of inherited thyroxine-binding globulin deficiency in Iran caused by a known de novo mutation in SERPINA7

摘要

Abstract Background Thyroxine-binding globulin (TBG) is the main transporter of thyroid hormones in human serum, encoded by the gene {TBG} (SERPINA7), located in long arm of X-chromosome (Xq21-q22). Deficiency of {SERPINA7} (serum protease inhibitor, clade A [alpha-1 antiproteinase, antitrypsin], member 7) leads to inherited {TBG} deficiency. Several mutations have been reported in the coding and noncoding regions of {SERPINA7} in association with {TGB} deficiency. Methods Automated chemiluminescence immunoassays were used to determine TSH, free and total {T4} and {T3} (fT4, TT4, TT3) and TBG. Direct {DNA} sequencing identified the mutation in SERPINA7. Results We present a 3 and 4/12 year old boy, born premature, who was mismanaged as hypothyroidism before referral to our center, and was diagnosed with {TBG} deficiency at our center with a hemizygous substitution in exon 1, position c.347T > A, leading to replacement of isoleucine for arginine in position 96 (considering the first 20 amino acid signal peptide). Conclusion This known mutation, reported as the first {SERPINA7} mutation in Iran, emphasizes the point that endocrinologists should pay more attention to inherited {TBG} to prevent unnecessary treatment.