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Iwasaki H, Suwanai H, Yakou F, Sakai H, Ishii K, Hara N, Buckle AM, Kanekura K, Miyagi T, Narumi S, Suzuki R. Disulfide Bonds of Thyroid Peroxidase Are Critical Elements for Subcellular Localization, Proteasome-Dependent Degradation, and Enzyme Activity. Thyroid 2024; 34:659-667. [PMID: 38482822 DOI: 10.1089/thy.2023.0514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Abstract
Background: Congenital hypothyroidism (CH) is caused by mutations in cysteine residues, including Cys655 and Cys825 that form disulfide bonds in thyroid peroxidase (TPO). It is highly likely that these disulfide bonds could play an important role in TPO activity. However, to date, no study has comprehensively analyzed cysteine mutations that form disulfide bonds in TPO. In this study, we induced mutations in cysteine residues involved in disulfide bonds formation and analyzed their effect on subcellular localization, degradation, and enzyme activities to evaluate the importance of disulfide bonds in TPO activity. Methods: Vector plasmid TPO mutants, C655F and C825R, known to occur in CH, were transfected into HEK293 cells. TPO activity and protein expression levels were measured by the Amplex red assay and Western blotting. The same procedure was performed in the presence of MG132 proteasome inhibitor. Subcellular localization was determined using immunocytochemistry and flow cytometry. The locations of all disulfide bonds within TPO were predicted using in silico analysis. All TPO mutations associated with disulfide bonds were induced. TPO activity and protein expression levels were also measured in all TPO mutants associated with disulfide bonds using the Amplex red assay and Western blotting. Results: C655F and C825R showed significantly decreased activity and protein expression compared with the wild type (WT) (p < 0.05). In the presence of the MG132 proteasome inhibitor, the protein expression level of TPO increased to a level comparable with that of the WT without increases in its activity. The degree of subcellular distribution of TPO to the cell surface in the mutants was lower compared with the WT TPO. Twenty-four cysteine residues were involved in the formation of 12 disulfide bonds in TPO. All TPO mutants harboring an amino acid substitution in each cysteine showed significantly reduced TPO activity and protein expression levels. Furthermore, the differences in TPO activity depended on the position of the disulfide bond. Conclusions: All 12 disulfide bonds play an important role in the activity of TPO. Furthermore, the mutations lead to misfolding, degradation, and membrane insertion.
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Affiliation(s)
- Hajime Iwasaki
- Department of Diabetes, Metabolism, and Endocrinology, Tokyo Medical University, Tokyo, Japan
| | - Hirotsugu Suwanai
- Department of Diabetes, Metabolism, and Endocrinology, Tokyo Medical University, Tokyo, Japan
| | - Fumiyoshi Yakou
- Department of Diabetes, Metabolism, and Endocrinology, Tokyo Medical University, Tokyo, Japan
| | - Hiroyuki Sakai
- Department of Diabetes, Metabolism, and Endocrinology, Tokyo Medical University, Tokyo, Japan
| | - Keitaro Ishii
- Department of Diabetes, Metabolism, and Endocrinology, Tokyo Medical University, Tokyo, Japan
| | - Natsuko Hara
- Department of Diabetes, Metabolism, and Endocrinology, Tokyo Medical University, Tokyo, Japan
| | - Ashley M Buckle
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Kohsuke Kanekura
- Department of Pharmacology, Tokyo Medical University, Tokyo, Japan
| | - Tamami Miyagi
- Department of Pharmacology, Tokyo Medical University, Tokyo, Japan
| | - Satoshi Narumi
- Department of Pediatrics, Keio University School of Medicine, Tokyo, Japan
| | - Ryo Suzuki
- Department of Diabetes, Metabolism, and Endocrinology, Tokyo Medical University, Tokyo, Japan
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de Souza JS. Thyroid hormone biosynthesis and its role in brain development and maintenance. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2023; 142:329-365. [PMID: 39059990 DOI: 10.1016/bs.apcsb.2023.12.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/28/2024]
Abstract
Thyroid hormones are critical modulators in the physiological processes necessary to virtually all tissues, with exceptionally fundamental roles in brain development and maintenance. These hormones regulate essential neurodevelopment events, including neuronal migration, synaptogenesis, and myelination. Additionally, thyroid hormones are crucial for maintaining brain homeostasis and cognitive function in adulthood. This chapter aims to offer a comprehensive understanding of thyroid hormone biosynthesis and its intricate role in brain physiology. Here, we described the mechanisms underlying the biosynthesis of thyroid hormones, their influence on various aspects of brain development and ongoing maintenance, and the proteins in the brain that are responsive to these hormones. This chapter was geared towards broadening our understanding of thyroid hormone action in the brain, shedding light on potential therapeutic targets for neurodevelopmental and neurodegenerative disorders.
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Affiliation(s)
- Janaina Sena de Souza
- Department of Pediatrics and Cellular & Molecular Medicine, School of Medicine, University of California San Diego, La Jolla, CA, United States.
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3
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Naqvi SF, Yıldız-Bölükbaşı E, Afzal M, Nalbant G, Mumtaz S, Tolun A, Malik S. Homozygous Mutations in Thyroid Peroxidase (TPO) in Hypothyroidism with Intellectual Disability, Developmental Delay, and Hearing and Ocular Anomalies in Two Families: Severe Manifestation of Untreated TPO-deficiency Poses a Diagnostic Dilemma. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2023; 96:347-365. [PMID: 37780999 PMCID: PMC10524819 DOI: 10.59249/ssrg6507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Intellectual disability (ID) involves compromised intellectual, learning and cognitive skills, and behavioral capabilities with reduced psychomotor skills. One of the preventable causes of ID is congenital hypothyroidism (CH), which may be due to biallelic mutations in thyroid peroxidase (TPO). In low- and middle-income countries with no newborn screening programs, CH poses a great risk of ID and long-term morbidity. We report two large Pakistani families with a total of 16 patients afflicted with CH. Detailed clinical and behavioral assessments, SNP-based homozygosity mapping, linkage analysis, and exome sequencing were performed. Initially, affected individuals were referred as suffering ID (in 11 of 16 patients) and developmental delay (in 14). Secondary/associated features were verbal apraxia (in 13), goiter (in 12), short stature (in 11), limb hypotonia (in 14), no pubertal onset (five of 10 of age ≥14 years), high myopia (in eight), muscle cramps (in six), and in some, variable microcephaly and enuresis/encopresis, fits, chronic fatigue, and other behavioral symptoms, which are not characteristics of CH. Molecular genetic analyses led to the discovery of homozygous variants in TPO: novel missense variant c.719A>G (p.Asp240Gly) in family 1 and rare c.2315A>G (p.Tyr772Cys) in family 2. In low-resource countries where neonatal screening programs do not include a CH test, the burden of neurodevelopmental disorders is likely to be increased due to untreated CH. Secondly, in the background of the high prevalence of recessive disorders due to high parental consanguinity, the severe manifestation of TPO-deficiency mimics a wide range of neurological and other presentations posing a diagnostic dilemma.
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Affiliation(s)
- Syeda Farwa Naqvi
- Human Genetics Program, Department of Zoology, Faculty
of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Esra Yıldız-Bölükbaşı
- Department of Molecular Biology and Genetics, Boğaziçi
University, Istanbul, Türkiye
| | - Muhammad Afzal
- Human Genetics Program, Department of Zoology, Faculty
of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
| | - Gökhan Nalbant
- Department of Biostatistics and Bioinformatics,
Institute of Health Sciences, Acibadem Mehmet Ali Aydınlar University, Istanbul,
Türkiye
| | - Sara Mumtaz
- Department of Biological Sciences, National University
of Medical Sciences, Rawalpindi, Pakistan
| | - Aslıhan Tolun
- Department of Molecular Biology and Genetics, Istanbul
Technical University, Istanbul, Türkiye
| | - Sajid Malik
- Human Genetics Program, Department of Zoology, Faculty
of Biological Sciences, Quaid-i-Azam University, Islamabad, Pakistan
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4
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Molina MF, Pio MG, Scheps KG, Adrover E, Abelleyro MM, Targovnik HM, Rivolta CM. Curating the gnomAD database: Report of novel variants in the thyroid peroxidase gene using in silico bioinformatics algorithms and a literature review. Mol Cell Endocrinol 2022; 558:111748. [PMID: 35995307 DOI: 10.1016/j.mce.2022.111748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/31/2022] [Accepted: 08/01/2022] [Indexed: 12/15/2022]
Abstract
Thyroid peroxidase (TPO) is a membrane-bound glycoprotein located at the apical side of the thyroid follicular cells that catalyzes both iodination and coupling of iodotyrosine residues within the thyroglobulin molecule, leading to the synthesis of thyroid hormone. Variants in TPO cause congenital hypothyroidism (CH) by iodide organification defect and are commonly inherited in an autosomal recessive fashion. In the present work, we report a detailed population analysis and bioinformatic prediction of the TPO variants indexed in the Genome Aggregation Database (gnomAD) v2.1.1. The proportion of missense cysteine variants and nonsense, frameshift, and splice acceptor/donor variants were analyzed in each ethnic group (European (Non-Finnish), European (Finnish), African/African Americans, Latino/Admixed American, East Asian, South Asian, Ashkenazi Jewish, Other). The results showed a clear predominance of frameshift variants in the East Asian (82%) and European (Finnish) (75%) population, whereas the splice site variants predominate in African/African Americans (99.46%), Other (96%), Latino/Admixed American (94%), South Asian (86%), European (Non-Finnish) (56%) and Ashkenazi Jewish (56%) populations. The analysis of the distribution of the variants indexed in gnomAD v2.1.1 database revealed that most missense variants identified in the An peroxidase domain map in exon 8, followed by exons 11, 7 and 9, and finally in descending order by exons 10, 6, 12 and 5. In total, 183 novel TPO variants were described (13 missense cysteine's variants, 158 missense variants involving the An peroxidase domain and 12 splicing acceptor or donor sites variants) which were not reported in the literature and that would have deleterious effects on prediction programs. In the gnomAD v2.1.1 population, the estimated prevalence of heterozygous carriers of the potentially damaging variants was 1:77. In conclusion, we provide an updated and curated reference source of new TPO variants for application in clinical diagnosis and genetic counseling. Also, this work contributes to elucidating the molecular basis of CH associated with TPO defects.
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Affiliation(s)
- Maricel F Molina
- Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Mauricio Gomes Pio
- Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Karen G Scheps
- Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Ezequiela Adrover
- Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Miguel M Abelleyro
- CONICET-Academia Nacional de Medicina, Instituto de Medicina Experimental (IMEX), Buenos Aires, Argentina
| | - Héctor M Targovnik
- Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Carina M Rivolta
- Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina.
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5
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Molina MF, Papendieck P, Sobrero G, Balbi VA, Belforte FS, Martínez EB, Adrover E, Olcese MC, Chiesa A, Miras MB, González VG, Pio MG, González-Sarmiento R, Targovnik HM, Rivolta CM. Mutational screening of the TPO and DUOX2 genes in Argentinian children with congenital hypothyroidism due to thyroid dyshormonogenesis. Endocrine 2022; 77:86-101. [PMID: 35507000 DOI: 10.1007/s12020-022-03054-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 04/02/2022] [Indexed: 02/07/2023]
Abstract
PURPOSE Primary congenital hypothyroidism (CH) is the most common endocrine disease in children and one of the preventable causes of both cognitive and motor deficits. We present a genetic and bioinformatics investigation of rational clinical design in 17 Argentine patients suspected of CH due to thyroid dyshormonogenesis (TDH). METHODS Next-Generation Sequencing approach was used to identify variants in Thyroid Peroxidase (TPO) and Dual Oxidase 2 (DUOX2) genes. A custom panel targeting 7 genes associated with TDH [(TPO), Iodothyrosine Deiodinase I (IYD), Solute Carrier Family 26 Member 4 (SLC26A4), Thyroglobulin (TG), DUOX2, Dual Oxidase Maturation Factor 2 (DUOXA2), Solute Carrier Family 5 Member 5 (SLC5A5)] and 4 associated with thyroid dysembryogenesis [PAX8, FOXE1, NKX2-1, Thyroid Stimulating Hormone Receptor (TSHR)] has been designed. Additionally, bioinformatic analysis and structural modeling were carried out to predict the disease-causing potential variants. RESULTS Four novel variants have been identified, two in TPO: c.2749-2 A > C and c.2752_2753delAG, [p.Ser918Cysfs*62] and two variants in DUOX2 gene: c.425 C > G [p.Pro142Arg] and c.2695delC [p.Gln899Serfs*21]. Eighteen identified TPO, DUOX2 and IYD variants were previously described. We identified potentially pahogenic biallelic variants in TPO and DUOX2 in 7 and 2 patients, respectively. We also detected a potentially pathogenic monoallelic variant in TPO and DUOX2 in 7 and 1 patients respectively. CONCLUSIONS 22 variants have been identified associated with TDH. All described novel mutations occur in domains important for protein structure and function, predicting the TDH phenotype.
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Affiliation(s)
- Maricel F Molina
- Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Patricia Papendieck
- Centro de Investigaciones Endocrinológicas, CEDIE-CONICET, División Endocrinología, Hospital de Niños "Ricardo Gutiérrez", Buenos Aires, Argentina
| | - Gabriela Sobrero
- Servicio de Endocrinología, Hospital de Niños Santísima Trinidad, Córdoba, Argentina
| | - Viviana A Balbi
- Servicio de Endocrinología, Hospital de Niños "Sor María Ludovica", La Plata, Argentina
| | - Fiorella S Belforte
- Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Elena Bueno Martínez
- Unidad de Medicina Molecular-Departamento de Medicina, IBMCC and IBSAL, Universidad de Salamanca-CSIC, Salamanca, España
| | - Ezequiela Adrover
- Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - María C Olcese
- Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ana Chiesa
- Centro de Investigaciones Endocrinológicas, CEDIE-CONICET, División Endocrinología, Hospital de Niños "Ricardo Gutiérrez", Buenos Aires, Argentina
| | - Mirta B Miras
- Servicio de Endocrinología, Hospital de Niños Santísima Trinidad, Córdoba, Argentina
| | - Verónica G González
- Servicio de Endocrinología, Hospital de Niños "Sor María Ludovica", La Plata, Argentina
| | - Mauricio Gomes Pio
- Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Rogelio González-Sarmiento
- Unidad de Medicina Molecular-Departamento de Medicina, IBMCC and IBSAL, Universidad de Salamanca-CSIC, Salamanca, España
| | - Héctor M Targovnik
- Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Universidad de Buenos Aires, Buenos Aires, Argentina
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Carina M Rivolta
- Facultad de Farmacia y Bioquímica. Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Universidad de Buenos Aires, Buenos Aires, Argentina.
- Instituto de Inmunología, Genética y Metabolismo (INIGEM), CONICET-Universidad de Buenos Aires, Buenos Aires, Argentina.
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6
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Citterio CE, Rivolta CM, Targovnik HM. Structure and genetic variants of thyroglobulin: Pathophysiological implications. Mol Cell Endocrinol 2021; 528:111227. [PMID: 33689781 DOI: 10.1016/j.mce.2021.111227] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 01/22/2021] [Accepted: 02/23/2021] [Indexed: 02/07/2023]
Abstract
Thyroglobulin (TG) plays a main role in the biosynthesis of thyroid hormones (TH), and, thus, it is involved in a wide range of vital functions throughout the life cycle of all vertebrates. Deficiency of TH production due to TG genetic variants causes congenital hypothyroidism (CH), with devastating consequences such as intellectual disability and impaired growth if untreated. To this day, 229 variations in the human TG gene have been identified while the 3D structure of TG has recently appeared. Although TG deficiency is thought to be of autosomal recessive inheritance, the introduction of massive sequencing platforms led to the identification of a variety of monoallelic TG variants (combined with mutations in other thyroid gene products) opening new questions regarding the possibility of oligogenic inheritance of the disease. In this review we discuss remarkable advances in the understanding of the TG architecture and the pathophysiology of CH associated with TG defects, providing new insights for the management of congenital disorders as well as counseling benefits for families with a history of TG abnormalities. Moreover, we summarize relevant aspects of TH synthesis within TG and offer an updated analysis of animal and cellular models of TG deficiency for pathophysiological studies of thyroid dyshormonogenesis while highlighting perspectives for new investigations. All in all, even though there has been sustained progress in understanding the role of TG in thyroid pathophysiology during the past 50 years, functional characterization of TG variants remains an important area of study for future advancement in the field.
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Affiliation(s)
- Cintia E Citterio
- Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires. Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Carina M Rivolta
- Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires. Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Héctor M Targovnik
- Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires. Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina.
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7
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Wang H, Wang W, Chen X, Shi H, Shi Y, Ding G. Screening and Functional Analysis of TPO Gene Mutations in a Cohort of Chinese Patients With Congenital Hypothyroidism. Front Endocrinol (Lausanne) 2021; 12:774941. [PMID: 35002963 PMCID: PMC8729100 DOI: 10.3389/fendo.2021.774941] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 11/24/2021] [Indexed: 01/18/2023] Open
Abstract
BACKGROUNDS As a crucial enzyme in thyroid hormone synthesis, the genetic defective thyroid peroxidase (TPO) was one of the main genetic factors leading to congenital hypothyroidism (CH). METHODS Mutations in the TPO gene were screened and identified in 219 patients with CH from northwest China by using high-throughput sequencing and bioinformatics analysis. The biological function of detected variants was studied by in vitro experiments and homology modeling. RESULTS Nineteen rare variants, including seven novel ones, were detected in 17 of 219 patients (7.8%). Most cases were detected with one single heterozygous variant, and only two patients were detected with multiple variants, i.e., compounds for (1) IVS7-1G>A, p.Ala443Val, and p.Arg769Trp and (2) p.Asn592Ser and p.Asn798Lys. The biological function of the four missense mutations (i.e., p.Ala443Val, p.Arg769Trp, p.Asn592Ser, and p.Asn798Lys) they carried were further studied. Experimental data showed that these four mutations did not affect the protein expression level of the TPO gene but remarkably reduced the peroxidase activity toward guaiacol oxidation, retaining 8-32% of activity of the wild-type protein. The comparison of the predicted 3-D structures of wild-type and mutant TPO proteins showed that these four amino acid substitutions changed the non-covalent interactions of studied residues that might alter the structure and function of the TPO protein. CONCLUSION This study was the first to analyze the TPO mutation spectrum of patients with CH in northwest China. Our data indicated that the TPO mutation was not a common reason to cause CH in China. The functional data may help to clarify the structure-function relationship of the TPO protein and provide further evidence for the elucidation of the genetic etiology of CH.
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Affiliation(s)
- Huijjuan Wang
- The National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi’an, China
- *Correspondence: Huijjuan Wang, ; Guifeng Ding,
| | - Wenxia Wang
- The National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi’an, China
| | - Xi Chen
- Pediatrics, Urumqi Maternal and Child Health Care Hospital, Urumqi, China
| | - Hailong Shi
- College of Basic Medicine, Shaanxi University of Chinese Medicine, Xianyang, China
| | - Yinmin Shi
- The National Engineering Research Center for Miniaturized Detection Systems, Northwest University, Xi’an, China
| | - Guifeng Ding
- Obstetrics and Gynecology Department, Urumqi Maternal and Child Health Care Hospital, Urumqi, China
- *Correspondence: Huijjuan Wang, ; Guifeng Ding,
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8
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Camats N, Baz-Redón N, Fernández-Cancio M, Clemente M, Campos-Martorell A, Jaimes N, Antolín M, Garcia-Arumí E, Blasco-Pérez L, Paramonov I, Mogas E, Soler-Colomer L, Yeste D. Phenotypic Variability of Patients With PAX8 Variants Presenting With Congenital Hypothyroidism and Eutopic Thyroid. J Clin Endocrinol Metab 2021; 106:e152-e170. [PMID: 33029631 DOI: 10.1210/clinem/dgaa711] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/05/2020] [Indexed: 11/19/2022]
Abstract
PURPOSE Thyroid dyshormonogenesis is a heterogeneous group of hereditary diseases produced by a total/partial blockage of the biochemical processes of thyroid-hormone synthesis and secretion. Paired box 8 (PAX8) is essential for thyroid morphogenesis and thyroid hormone synthesis. We aimed to identify PAX8 variants in patients with thyroid dyshormonogenesis and to analyze them with in vitro functional studies. PATIENTS AND METHODS Nine pediatric patients with a eutopic thyroid gland were analyzed by the Catalan screening program for congenital hypothyroidism. Scintigraphies showed absent, low, or normal uptake. Only one patient had a hypoplastic gland. On reevaluation, perchlorate discharge test was negative or compatible with partial iodine-organization deficit. After evaluation, 8 patients showed permanent mild or severe hypothyroidism. Massive-sequencing techniques were used to detect variants in congenital hypothyroidism-related genes. In vitro functional studies were based on transactivating activity of mutant PAX8 on a TG-gene promoter and analyzed by a dual-luciferase assays. RESULTS We identified 7 heterozygous PAX8 exonic variants and 1 homozygous PAX8 splicing variant in 9 patients with variable phenotypes of thyroid dyshormonogenesis. Five were novel and 5 variants showed a statistically significant impaired transcriptional activity of TG promoter: 51% to 78% vs the wild type. CONCLUSIONS Nine patients presented with PAX8 candidate variants. All presented with a eutopic thyroid gland and 7 had deleterious variants. The phenotype of affected patients varies considerably, even within the same family; but, all except the homozygous patient presented with a normal eutopic thyroid gland and thyroid dyshormonogenesis. PAX8 functional studies have shown that 6 PAX8 variants are deleterious. Our studies have proven effective in evaluating these variants.
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Affiliation(s)
- Núria Camats
- Growth and Development group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
- CIBERER, ISCIII, Madrid, Spain
| | - Noelia Baz-Redón
- Growth and Development group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
- Pediatrics, Obstetrics and Gynecology and Preventive Medicine Department, Universitat Autònoma de Barcelona, Bellaterra, Spain
| | - Mónica Fernández-Cancio
- Growth and Development group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
- CIBERER, ISCIII, Madrid, Spain
| | - María Clemente
- Growth and Development group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
- CIBERER, ISCIII, Madrid, Spain
- Pediatrics, Obstetrics and Gynecology and Preventive Medicine Department, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Pediatric Endocrinology Section, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Ariadna Campos-Martorell
- Growth and Development group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
- Pediatrics, Obstetrics and Gynecology and Preventive Medicine Department, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Pediatric Endocrinology Section, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Nadya Jaimes
- Department of Pediatric Endocrinology, Hospital Fundación la Misericordia HOMI, Bogotá, Colombia
| | - María Antolín
- Department of Clinical and Molecular Genetics and Rare Disease, Hospital Universitari Vall d'Hebron, Barcelona, Spain
- Medicine Genetics Group, VHIR, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Elena Garcia-Arumí
- Department of Clinical and Molecular Genetics and Rare Disease, Hospital Universitari Vall d'Hebron, Barcelona, Spain
- Medicine Genetics Group, VHIR, Hospital Universitari Vall d'Hebron, Barcelona, Spain
- Research Group on Neuromuscular and Mitochondrial Disorders, VHIR, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Laura Blasco-Pérez
- Department of Clinical and Molecular Genetics and Rare Disease, Hospital Universitari Vall d'Hebron, Barcelona, Spain
- Medicine Genetics Group, VHIR, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Ida Paramonov
- Department of Clinical and Molecular Genetics and Rare Disease, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Eduard Mogas
- Pediatric Endocrinology Section, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Laura Soler-Colomer
- Pediatric Endocrinology Section, Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Diego Yeste
- Growth and Development group, Vall d'Hebron Research Institute (VHIR), Hospital Universitari Vall d'Hebron, Barcelona, Spain
- CIBERER, ISCIII, Madrid, Spain
- Pediatrics, Obstetrics and Gynecology and Preventive Medicine Department, Universitat Autònoma de Barcelona, Bellaterra, Spain
- Pediatric Endocrinology Section, Hospital Universitari Vall d'Hebron, Barcelona, Spain
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9
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Novel homozygous variant in the TPO gene associated with congenital hypothyroidism and mild-intellectual disability. Hum Genome Var 2020; 7:41. [PMID: 33298898 PMCID: PMC7695822 DOI: 10.1038/s41439-020-00129-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 08/13/2020] [Accepted: 08/18/2020] [Indexed: 12/16/2022] Open
Abstract
Congenital hypothyroidism (CH) is one of the most common hereditary disorders affecting neonates worldwide. CH is a multifactorial complex disorder and can be caused by either environmental factors or genetic factors. We studied one Pakistani family with segregating mutations in CH inherited in an autosomal recessive manner. Using whole-exome sequencing (WES), we found a novel homozygous missense variant (c.2315A>G; p.Tyr772Cys) in the thyroid peroxidase (TPO) gene. Different bioinformatics prediction tools and Sanger sequencing were performed to verify the identified variant. Our findings highlight the importance of this gene in causing CH and mild-intellectual disability (ID) in two affected brothers. WES is a convenient and useful tool for the clinical diagnosis of CH and other associated disorders.
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10
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Targovnik HM, Scheps KG, Rivolta CM. Defects in protein folding in congenital hypothyroidism. Mol Cell Endocrinol 2020; 501:110638. [PMID: 31751626 DOI: 10.1016/j.mce.2019.110638] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 10/21/2019] [Accepted: 11/01/2019] [Indexed: 12/26/2022]
Abstract
Primary congenital hypothyroidism (CH) is the most common endocrine disease in children and one of the most common preventable causes of both cognitive and motor deficits. CH is a heterogeneous group of thyroid disorders in which inadequate production of thyroid hormone occurs due to defects in proteins involved in the gland organogenesis (dysembryogenesis) or in multiple steps of thyroid hormone biosynthesis (dyshormonogenesis). Dysembryogenesis is associated with genes responsible for the development or growth of thyroid cells: such as NKX2-1, FOXE1, PAX8, NKX2-5, TSHR, TBX1, CDCA8, HOXD3 and HOXB3 resulting in agenesis, hypoplasia or ectopia of thyroid gland. Nevertheless, the etiology of the dysembryogenesis remains unknown for most cases. In contrast, the majority of patients with dyshormonogenesis has been linked to mutations in the SLC5A5, SLC26A4, SLC26A7, TPO, DUOX1, DUOX2, DUOXA1, DUOXA2, IYD or TG genes, which usually originate goiter. About 800 genetic mutations have been reported to cause CH in patients so far, including missense, nonsense, in-frame deletion and splice-site variations. Many of these mutations are implicated in specific domains, cysteine residues or glycosylation sites, affecting the maturation of nascent proteins that go through the secretory pathway. Consequently, misfolded proteins are permanently entrapped in the endoplasmic reticulum (ER) and are translocated to the cytosol for proteasomal degradation by the ER-associated degradation (ERAD) machinery. Despite of all these remarkable advances in the field of the CH pathogenesis, several points on the development of this disease remain to be elucidated. The continuous study of thyroid gene mutations with the application of new technologies will be useful for the understanding of the intrinsic mechanisms related to CH. In this review we summarize the present status of knowledge on the disorders in the protein folding caused by thyroid genes mutations.
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Affiliation(s)
- Héctor M Targovnik
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina.
| | - Karen G Scheps
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Carina M Rivolta
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología, Biotecnología y Genética/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
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11
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Yakou F, Suwanai H, Ishikawa T, Itou M, Shikuma J, Miwa T, Sakai H, Kanekura K, Narumi S, Suzuki R, Odawara M. A Novel Homozygous Mutation of Thyroid Peroxidase Gene Abolishes a Disulfide Bond Leading to Congenital Hypothyroidism. Int J Endocrinol 2020; 2020:9132372. [PMID: 32908504 PMCID: PMC7477596 DOI: 10.1155/2020/9132372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 08/12/2020] [Accepted: 08/23/2020] [Indexed: 11/17/2022] Open
Abstract
Congenital hypothyroidism (CH) is the most prevalent congenital endocrine disorder and causes mental retardation. A male Japanese patient with first cousin marriage parents was diagnosed as CH at 10 months. He was born before introduction of mass screening for CH. With continuous thyroid hormone replacement therapy, normal thyroid hormone status was maintained until adulthood. Genetic screening of next-generation sequencing was performed at the age of 52 years, and we identified a new homozygous thyroid peroxidase (TPO) gene mutation (GRCh38.p13, chromosome 2 at position 1493997, c.1964 G>T, p.Cys655Phe). TPO is an important enzyme to produce thyroid hormone. As demonstrated by a homology analysis of TPO proteins among different species, cysteine 655 residue is highly conserved, suggesting an important role in maintaining TPO function and structure. An in silico study with three-dimensional structure of the novel mutation was performed and suggested that the mutation abolished disulfide bond between cysteines at positions 598 and 655. An in vitro functional analysis using HEK293 cells revealed that TPO activity of the mutant was significantly impaired compared with that of the wild type. Furthermore, study of immunohistochemistry showed that localization of TPO in cells did not differ between the wild type and the mutant. In conclusion, this single disulfide bond loss mutation of a new TPO homozygous mutation, p.Cys655Phe, reduced TPO activity and caused congenital hypothyroidism without affecting subcellular localization of TPO proteins.
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Affiliation(s)
- Fumiyoshi Yakou
- Tokyo Medical University, Department of Diabetes, Metabolism and Endocrinology, Tokyo 160-0023, Japan
| | - Hirotsugu Suwanai
- Tokyo Medical University, Department of Diabetes, Metabolism and Endocrinology, Tokyo 160-0023, Japan
| | - Takuya Ishikawa
- Tokyo Medical University, Department of Diabetes, Metabolism and Endocrinology, Tokyo 160-0023, Japan
| | - Mariko Itou
- Tokyo Medical University, Department of Diabetes, Metabolism and Endocrinology, Tokyo 160-0023, Japan
| | - Jumpei Shikuma
- Tokyo Medical University, Department of Diabetes, Metabolism and Endocrinology, Tokyo 160-0023, Japan
| | - Takashi Miwa
- Tokyo Medical University, Department of Diabetes, Metabolism and Endocrinology, Tokyo 160-0023, Japan
| | - Hiroyuki Sakai
- Tokyo Medical University, Department of Diabetes, Metabolism and Endocrinology, Tokyo 160-0023, Japan
| | - Kohsuke Kanekura
- Tokyo Medical University, Department of Molecular Pathology, Tokyo 160-8402, Japan
| | - Satoshi Narumi
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo 157-8535, Japan
| | - Ryo Suzuki
- Tokyo Medical University, Department of Diabetes, Metabolism and Endocrinology, Tokyo 160-0023, Japan
| | - Masato Odawara
- Tokyo Medical University, Department of Diabetes, Metabolism and Endocrinology, Tokyo 160-0023, Japan
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12
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Yu B, Long W, Yang Y, Wang Y, Jiang L, Cai Z, Wang H. Newborn Screening and Molecular Profile of Congenital Hypothyroidism in a Chinese Population. Front Genet 2018; 9:509. [PMID: 30420871 PMCID: PMC6216286 DOI: 10.3389/fgene.2018.00509] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 10/10/2018] [Indexed: 12/12/2022] Open
Abstract
is the most gene mutation in Chinese CH patients.
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Affiliation(s)
- Bin Yu
- Changzhou Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Changzhou, China
| | - Wei Long
- Changzhou Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Changzhou, China
| | - Yuqi Yang
- Changzhou Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Changzhou, China
| | - Ying Wang
- Changzhou Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Changzhou, China
| | - Lihua Jiang
- Changzhou Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Changzhou, China
| | - Zhengmao Cai
- Changzhou Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Changzhou, China
| | - Huaiyan Wang
- Changzhou Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Changzhou, China
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13
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Chen XY, Qin XS. [Advances in genetic research of congenital hypothyroidism in China]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2018; 20:243-250. [PMID: 29530127 PMCID: PMC7389777 DOI: 10.7499/j.issn.1008-8830.2018.03.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/23/2018] [Indexed: 11/12/2023]
Abstract
Congenital hypothyroidism (CH), which results from insufficient thyroid hormone biosynthesis, is one of the most common neonatal endocrine disorders. Thyroid dysgenesis and thyroid dyshormonogenesis are the two causes of CH and either one will lead to deficiencies of enzymes during thyroid hormone biosynthesis and insufficient thyroid hormone biosynthesis. Recently, researchers have performed extensive studies on genetics of CH. This paper reviews genes reported to be associated with CH in China.
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Affiliation(s)
- Xiao-Yu Chen
- Clinical Laboratory, Shengjing Hospital of China Medical University, Shenyang 110004, China.
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14
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Chen XY, Qin XS. [Advances in genetic research of congenital hypothyroidism in China]. ZHONGGUO DANG DAI ER KE ZA ZHI = CHINESE JOURNAL OF CONTEMPORARY PEDIATRICS 2018; 20:243-250. [PMID: 29530127 PMCID: PMC7389777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/23/2018] [Indexed: 08/01/2024]
Abstract
Congenital hypothyroidism (CH), which results from insufficient thyroid hormone biosynthesis, is one of the most common neonatal endocrine disorders. Thyroid dysgenesis and thyroid dyshormonogenesis are the two causes of CH and either one will lead to deficiencies of enzymes during thyroid hormone biosynthesis and insufficient thyroid hormone biosynthesis. Recently, researchers have performed extensive studies on genetics of CH. This paper reviews genes reported to be associated with CH in China.
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Affiliation(s)
- Xiao-Yu Chen
- Clinical Laboratory, Shengjing Hospital of China Medical University, Shenyang 110004, China.
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15
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Leveraging human genetic and adverse outcome pathway (AOP) data to inform susceptibility in human health risk assessment. Mamm Genome 2018; 29:190-204. [DOI: 10.1007/s00335-018-9738-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 01/31/2018] [Indexed: 12/19/2022]
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16
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Fu C, Luo S, Long X, Li Y, She S, Hu X, Mo M, Wang Z, Chen Y, He C, Su J, Zhang Y, Lin F, Xie B, Li Q, Chen S. Mutation screening of the GLIS3 gene in a cohort of 592 Chinese patients with congenital hypothyroidism. Clin Chim Acta 2018; 476:38-43. [DOI: 10.1016/j.cca.2017.11.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 10/23/2017] [Accepted: 11/13/2017] [Indexed: 11/26/2022]
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17
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Abstract
Iodide Handling Disorders lead to defects of the biosynthesis of thyroid hormones (thyroid dyshormonogenesis, TD) and thereafter congenital hypothyroidism (CH), the most common endocrine disease characterized by low levels of circulating thyroid hormones. The prevalence of CH is 1 in 2000-3000 live births. Prevention of CH is based on prenatal diagnosis, carrier identification, and genetic counseling. In neonates a complete diagnosis of TD should include clinical examination, biochemical thyroid tests, thyroid ultrasound, radioiodine or technetium scintigraphy and perchlorate discharge test (PDT). Biosynthesis of thyroid hormones requires the presence of iodide, thyroid peroxidase (TPO), a supply of hydrogen peroxide (DUOX system), an iodine acceptor protein, thyroglobulin (TG), and the rescue and recycling of iodide by the action of iodotyrosine deiodinase or iodotyrosine dehalogenase 1 (IYD or DEHAL1). The iodide transport is a two-step process involving transporters located either in the basolateral or apical membranes, sodium iodide symporter (NIS) and pendrin (PDS), respectively. TD has been linked to mutations in the solute carrier family 5, member 5 transporter (SLC5A5, encoding NIS), solute carrier family 26, member 4 transporter (SLC26A4, encoding PDS), TPO, DUOX2, DUOXA2, TG and IYD genes. These mutations produce a heterogeneous spectrum of CH, with an autosomal recessive inheritance. Thereafter, the patients are usually homozygous or compound heterozygous for the gene mutations and the parents, carriers of one mutation. In the last two decades, considerable progress has been made in identifying the genetic and molecular causes of TD. Recent advances in DNA sequencing technology allow the massive screening and facilitate the studies of phenotype variability. In this article we included the most recent data related to disorders caused by mutations in NIS, TPO, TG and IYD.
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Affiliation(s)
- Héctor M Targovnik
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina.
| | - Cintia E Citterio
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
| | - Carina M Rivolta
- Universidad de Buenos Aires, Facultad de Farmacia y Bioquímica, Departamento de Microbiología, Inmunología y Biotecnología/Cátedra de Genética, Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Inmunología, Genética y Metabolismo (INIGEM), Buenos Aires, Argentina
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18
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Abstract
After the identification of thyroid H2O2 generation system (DUOX) and of its maturation factors (DUOXA), defects in DUOX2 and/or DUOXA2 were rapidly recognized as the possible cause of congenital hypothyroidism (CH) due to thyroid dyshormonogenesis. The present Review reports data on the prevalence of DUOX2 mutations, which is variable among different series but invariably high, pointing to DUOX2 defects as one of the leading causes of dyshormonogenesis. Differently, DUOXA defects seem to be rarely involved in the pathogenesis of CH. Genotype-phenotype correlations are also reported, highlighting the great intra- and inter-familial phenotype variability which appears to be a constant feature of the defects in the H2O2 generation systems. Finally, the hypotheses to explain the phenotypic variability of the DUOX2/A2 mutations are discussed, such as the existence of other H2O2 generating systems, the age variability in thyroid hormones requirements, the differences in ethnicity, in iodine intake, and in the methodological approaches.
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Affiliation(s)
- Marina Muzza
- Endocrine Unit, Fondazione IRCCS Ca' Granda Policlinico, Milan, Italy
| | - Laura Fugazzola
- Division of Endocrine and Metabolic Diseases, IRCCS Istituto Auxologico Italiano, Dept. of Pathophysiology and Transplantation, University of Milan, Milan, Italy.
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19
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Next-generation sequencing analysis of twelve known causative genes in congenital hypothyroidism. Clin Chim Acta 2017; 468:76-80. [PMID: 28215547 DOI: 10.1016/j.cca.2017.02.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Revised: 02/04/2017] [Accepted: 02/14/2017] [Indexed: 12/29/2022]
Abstract
BACKGROUND Gene variants have been reported to be associated with congenital hypothyroidism (CH), the purpose of this study was to analyze the mutation spectrum and prevalence of 12 known causative genes (TSHR, PAX8, NKX2.1, NKX2.5, FOXE1, DUOX2, TG, TPO, GLIS3, NIS, SLC26A4 and DEHAL1) in CH in China. METHODS Peripheral venous blood samples were collected from the patients. Genomic DNA was extracted from peripheral blood leukocytes. All exons and their exon-intron boundary sequences of the 12 known CH associated genes in 66 CH patients were screened by next-generation sequencing (NGS). RESULTS NGS analysis of 12 known CH associated genes revealed that 32 patients (32/66, 48.5%) were detected to have at least one potentially functional variant. 21, 9, 1, 1, 1 and 1 patients were found to have potential pathogenic variants in DUOX2, TG, PAX8, SLC26A4, TSHR and TPO genes, respectively. Novel variants included one DUOX2 and one TPO missense variants of unknown significance (VUS). CONCLUSION Our study expands the mutation spectrum of DUOX2 and TPO genes. 48.5% CH patients had at least one potential pathogenic variant. We found relatively high frequency of DUOX2 (31.8%) and TG (13.6%) mutations in our cohort.
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