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Heo J, Kim SM, Ryu HJ, Park H, Kim TH, Chung JH, Park HD, Kim SW. Identification of Mutations in the Thyroxine-Binding Globulin (TBG) Gene in Patients with TBG Deficiency in Korea. Endocrinol Metab (Seoul) 2022; 37:870-878. [PMID: 36475360 PMCID: PMC9816506 DOI: 10.3803/enm.2022.1591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 11/15/2022] [Indexed: 12/12/2022] Open
Abstract
BACKGRUOUND Thyroxine-binding globulin (TBG) is a major transporter protein for thyroid hormones. The serpin family A member 7 (SERPINA7) gene codes for TBG, and mutations of the SERPINA7 gene result in TBG deficiency. Although more than 40 mutations have been reported in several countries, only a few studies of TBG deficiency and SERPINA7 gene mutation have been performed in Korea. The aim of this study is to review the clinical presentations and laboratory findings of patients with TBG deficiency and to investigate the types of SERPINA7 gene mutation. METHODS Five unrelated Korean adults with TBG deficiency attending endocrinology clinic underwent SERPINA7 gene sequencing. Four patients harbored a SERPINA7 gene mutation. Serum thyroid hormones, anti-microsomal antibodies, and TBG were measured. Genomic DNA was extracted from whole blood. All exons and intron-exon boundaries of the TBG gene were amplified and sequencing was performed. RESULTS Two patients were heterozygous females, and the other two were hemizygous males. One heterozygous female had coexisting hypothyroidism. The other heterozygous female was erroneously prescribed levothyroxine at a local clinic. One hemizygous male harbored a novel mutation, p.Phe269Cysfs*18, which caused TBG partial deficiency. Three patients had the p.Leu372Phefs*23 mutation, which is known as TBG-complete deficiency Japan (TBG-CDJ) and was also presented in previous mutation analyses in Korea. CONCLUSION This study presents four patients diagnosed with TBG deficiency and provides the results of SERPINA7 gene sequencing. One novel mutation, p.Phe269Cysfs*18, causing TBD-partial deficiency and three cases of TBG-CDJ were demonstrated. It is necessary to identify TBG deficiency to prevent improper treatment. Also, sequencing of the SERPINA7 gene would provide valuable information about the TBG variants in Korea.
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Affiliation(s)
- Jung Heo
- Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sang-Mi Kim
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hyun Jin Ryu
- Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hyunju Park
- Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Tae Hyuk Kim
- Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jae Hoon Chung
- Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Hyung-Doo Park
- Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Sun Wook Kim
- Division of Endocrinology and Metabolism, Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
- Corresponding author: Sun Wook Kim. Department of Medicine, Thyroid Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 06351, Korea Tel: +82-2-3410-1653, Fax: +82-2-6918-4653 E-mail:
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Berger HR, Creech MK, Hannoush Z, Watanabe Y, Kargi A, Weiss RE. A NOVEL MUTATION CAUSING COMPLETE THYROID BINDING GLOBULIN DEFICIENCY (TBG-CD MIA) IN A MALE WITH COEXISTING GRAVES DISEASE. AACE Clin Case Rep 2017; 3:e134-e139. [PMID: 28553659 DOI: 10.4158/ep161421.cr] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
OBJECTIVE An asymptomatic male was found on screening to have a low serum TSH and total T4. The diagnosis of Graves' disease was made with positive thyroid stimulating immunoglobulin (TSI) and elevated free T4 in the presence of complete TBG deficiency (TBG-CD). Genetic testing of the patient and family members revealed a novel frameshift mutation in the TBG (SERPINA7) gene resulting in a complete deficiency of the protein. METHODS The laboratory testing included total T4, free T4 by analog method and direct dialysis and TBG measurements. Sequencing of genomic DNA was performed from peripheral blood. RESULTS A 35-year-old East Indian male was referred to endocrinology because of abnormal thyroid function tests (TFTs): TSH 0.01 mIU/L (0.4-3.6), total T4 3.0 µg/dl (5.5-10.5) done as part of a "routine office visit". Upon further testing, the serum free T4 2.0 ng/dl (0.8-1.8) and TSI 355% (<140% baseline) were elevated and the diagnosis of Graves' disease was made. TBG deficiency was suspected because the total T4 concentration was inconsistent with hyperthyroidism and further testing confirmed TBG was undetectable. Sequencing of the TBG gene revealed a novel hemizygous frameshift mutation: p.Ala64ProfsTer106, TBG-CD Mia (numbering excludes 20 a.a. signal peptide) associated with the complete deficiency of TBG in a patient with Graves' disease. CONCLUSION Patients with Graves' disease harboring a TBG mutation have conflicting TFTs. If a clinically hyperthyroid patient presents with normal or low total T4, serum TBG should be measured to identify an abnormality and prevent unnecessary testing.
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Affiliation(s)
- Hara Rosen Berger
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, FL, United States.,Jackson Health System, Miami, FL, United States
| | - Matthew K Creech
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Zeina Hannoush
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, FL, United States.,Jackson Health System, Miami, FL, United States
| | - Yui Watanabe
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Atil Kargi
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Roy E Weiss
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, University of Miami Miller School of Medicine, Miami, FL, United States
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Miura Y, Hershkovitz E, Inagaki A, Parvari R, Oiso Y, Phillip M. A novel mutation causing complete thyroxine-binding globulin deficiency (TBG-CD-Negev) among the Bedouins in southern Israel. J Clin Endocrinol Metab 2000; 85:3687-9. [PMID: 11061524 DOI: 10.1210/jcem.85.10.6899] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
T4-binding globulin (TBG) is the major thyroid hormone transport protein in human serum. Inherited TBG abnormalities do not usually alter the metabolic status and are transmitted in X-linked inheritance. A high prevalence of complete TBG deficiency (TBG-CD) has been reported among the Bedouin population in the Negev (southern Israel). In this study we report a novel single mutation causing complete TBG deficiency due to a deletion of the last base of codon 38 (exon 1), which led to a frame shift resulting in a premature stop at codon 51 and a presumed truncated peptide of 50 residues. This new 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 the Bedouins in the Negev. This report is the first to describe a mutation in a population with an unusually high prevalence of TBG-CD.
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Affiliation(s)
- Y Miura
- First Department of Internal Medicine, Nagoya University School of Medicine, Japan
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