Zebrafishduoxmutations provide a model for human congenital hypothyroidism

ABSTRACTThyroid dyshormonogenesis is a leading cause of congenital hypothyroidism, a highly prevalent but treatable condition. Thyroid hormone synthesis is dependent on the formation of reactive oxygen species (ROS). In humans, the primary sources for ROS production during thyroid hormone synthesis are the NADPH oxidase, DUOX1 and DUOX2. Indeed mutations inDUOX1andDUOX2have been linked with congenital hypothyroidism. Unlike humans, zebrafish has a single orthologue forDUOX1andDUOX2. In this study, we investigated the phenotypes associated with two nonsense mutant alleles of the singleduoxgene in zebrafish,sa9892andsa13017. Both alleles gave rise to readily observable phenotypes reminiscent of congenital hypothyroidism, from the larval stages through to adulthood. By using various methods to examine the external and internal phenotypes, we discovered a strong correlation between TH synthesis andduoxfunction, beginning from the early larval stage, when T4levels are already noticeably absent in the mutants. Loss of T4production resulted in growth retardation, pigmentation defects, ragged fins, thyroid hyperplasia / external goiter, and infertility. Remarkably all of these defects associated with chronic congenital hypothyroidism could be rescued with T4treatment, even when initiated when the fish had already reached adulthood. Our work suggests that these zebrafishduoxmutants may provide a powerful model to understand the aetiology of untreated and treated congenital hypothyroidism even in advance stages of development.

Download Full-text

Phenotypic Variability of Patients With PAX8 Variants Presenting With Congenital Hypothyroidism and Eutopic Thyroid

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/clinem/dgaa711 ◽

2020 ◽

Vol 106 (1) ◽

pp. e152-e170

Author(s):

Núria Camats ◽

Noelia Baz-Redón ◽

Mónica Fernández-Cancio ◽

María Clemente ◽

Ariadna Campos-Martorell ◽

...

Keyword(s):

Thyroid Hormone ◽

Thyroid Gland ◽

Congenital Hypothyroidism ◽

Phenotypic Variability ◽

Hereditary Diseases ◽

Hormone Synthesis ◽

Functional Studies ◽

Thyroid Hormone Synthesis ◽

Thyroid Dyshormonogenesis

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.

Download Full-text

Next-Generation Sequencing Analysis Reveals Frequent Familial Origin and Oligogenism in Congenital Hypothyroidism With Dyshormonogenesis

Frontiers in Endocrinology ◽

10.3389/fendo.2021.657913 ◽

2021 ◽

Vol 12 ◽

Author(s):

Isabelle Oliver-Petit ◽

Thomas Edouard ◽

Virginie Jacques ◽

Marie Bournez ◽

Audrey Cartault ◽

...

Keyword(s):

Next Generation Sequencing ◽

Thyroid Hormone ◽

Congenital Hypothyroidism ◽

Diagnostic Tools ◽

World Population ◽

Sequencing Analysis ◽

Next Generation ◽

Hormone Synthesis ◽

Thyroid Hormone Synthesis ◽

Generation Sequencing

ContextCongenital hypothyroidism (CH) is related to dyshormonogenesis in 15% to 40% of the world population and associated with homozygous or heterozygous variants in the main genes of the hormone synthesis pathway. Emerging diagnostic tools, such as next-generation sequencing (NGS), have been used to efficiently explore panels of genes and identify complex mechanisms of pathogenesis.ObjectiveWe explored 19 candidate genes known to be causative for permanent or transient CH to evaluate the role of complex gene variations in CH phenotype.Patients, Design and SettingUsing the NGS approach, we studied 65 newborns with thyroid dyshormonogenesis (TDH). New variants were assessed in silico for pathogenicity.ResultsAmong the 65 infants, 56.9% presented a variant in one or more genes of the thyroid hormone synthesis axis. We identified homozygous or compound heterozygous variants in the TG, DUOX2, TPO, or SLC5A5 genes in 10 infants and heterozygous variants in DUOX2, TG, TPO, and TSHR in 19 others. In seven cases, a heterozygous variant in the TG gene was the unique anomaly detected, but related to disturbed hormonal balance. Oligogenic variants were found in eight infants associated with severe CH and goiter in five of them.ConclusionThe systematic exploration of genes involved in thyroid hormone synthesis by NGS in TDH showed high diagnostic relevance. Oligogenic inheritance could be related to phenotypic heterogeneity and a high frequency of goiter.

Download Full-text

Congenital Hypothyroidism, Dwarfism, and Hearing Impairment Caused by a Missense Mutation in the Mouse Dual Oxidase 2 Gene, Duox2

Molecular Endocrinology ◽

10.1210/me.2007-0085 ◽

2007 ◽

Vol 21 (7) ◽

pp. 1593-1602 ◽

Cited By ~ 69

Author(s):

Kenneth R. Johnson ◽

Coleen C. Marden ◽

Patricia Ward-Bailey ◽

Leona H. Gagnon ◽

Roderick T. Bronson ◽

...

Keyword(s):

Thyroid Hormone ◽

Congenital Hypothyroidism ◽

Genetic Model ◽

Mutant Mice ◽

Tectorial Membrane ◽

Thyroid Peroxidase ◽

Hormone Synthesis ◽

Thyroid Hormone Synthesis ◽

Organ Systems ◽

Dual Oxidase

Abstract Dual oxidases generate the hydrogen peroxide needed by thyroid peroxidase for the incorporation of iodine into thyroglobulin, an essential step in thyroid hormone synthesis. Mutations in the human dual oxidase 2 gene, DUOX2, have been shown to underlie several cases of congenital hypothyroidism. We report here the first mouse Duox2 mutation, which provides a new genetic model for studying the specific function of DUOX2 in the thyroid gland and in other organ systems where it is hypothesized to play a role. We mapped the new spontaneous mouse mutation to chromosome 2 and identified it as a T>G base pair change in exon 16 of Duox2. The mutation changes a highly conserved valine to glycine at amino acid position 674 (V674G) and was named “thyroid dyshormonogenesis” (symbol thyd) to signify a defect in thyroid hormone synthesis. Thyroid glands of mutant mice are goitrous and contain few normal follicles, and anterior pituitaries are dysplastic. Serum T4 in homozygotes is about one-tenth the level of controls and is accompanied by a more than 100-fold increase in TSH. The weight of adult mutant mice is approximately half that of littermate controls, and serum IGF-I is reduced. The cochleae of mutant mice exhibit abnormalities characteristic of hypothyroidism, including a delayed formation of the inner sulcus and tunnel of Corti and an abnormally thickened tectorial membrane. Hearing thresholds of adult mutant mice are on average 50–60 decibels (dB) above those of controls.

Download Full-text

Genetic Manipulation on Zebrafish duox Recapitulate the Clinical Manifestations of Congenital Hypothyroidism

Endocrinology ◽

10.1210/endocr/bqab101 ◽

2021 ◽

Author(s):

Feng Sun ◽

Ya Fang ◽

Man-Man Zhang ◽

Rui-Jia Zhang ◽

Feng-Yao Wu ◽

...

Keyword(s):

Thyroid Hormone ◽

Thyroid Hormones ◽

Congenital Hypothyroidism ◽

Growth Retardation ◽

Genetic Manipulation ◽

Clinical Manifestations ◽

Primary Sources ◽

H2o2 Production ◽

Endocrine Disorder ◽

Thyroid Dyshormonogenesis

Abstract Congenital hypothyroidism (CH) is a highly prevalent but treatable neonatal endocrine disorder. Thyroid dyshormonogenesis is the main cause of congenital hypothyroidism in Chinese CH patients and DUOX2 is the most frequent mutated gene involved in H2O2 production. In human, the primary sources for H2O2 production are DUOX1 and DUOX2, while in zebrafish, there is only a single orthologue for DUOX1 and DUOX2. In this study, duox mutant zebrafish were generated through knockdown duox by morpholino or knockout duox by CRISPR Cas9. The associated phenotypes were investigated and rescued by thyroxine (T4) treatment. Mutant zebrafish displayed hypothyroid phenotypes including growth retardation and goiter and infertility. Homozygous mutants in adults also displayed extra-thyroidal abnormal phenotypes including lacking barbels, pigmentation defects, erythema in the opercular region, ragged fins and delayed scales. All these abnormal phenotypes can be rescued by 10 nM T4 treatment. Strikingly, the fertility of zebrafish was dependent on thyroid hormone, T4 treatment should be continued and cannot be stopped over two weeks in hypothyroid zebrafish in order to achieve fertility. Thyroid hormones played a role in the developing and maturing of reproductive cells. Our work indicated that duox mutant zebrafish may provide a model for human congenital hypothyroidism.

Download Full-text

BIOCHEMICAL DEFECTS IN THYROID HORMONE SYNTHESIS AND THEIR RELATION TO ENDEMIC GOITER

Acta Endocrinologica ◽

10.1530/acta.0.074s034 ◽

1973 ◽

Vol 74 (2_Suppla) ◽

pp. S34-S44

Author(s):

Leslie J. DeGroot

Keyword(s):

Thyroid Hormone ◽

Endemic Goiter ◽

Hormone Synthesis ◽

Thyroid Hormone Synthesis

Download Full-text

THE INFLUENCE OF THE PLASMA INORGANIC IODINE CONCENTRATION ON THYROID FUNCTION IN DEHALOGENASE DEFICIENCY

Acta Endocrinologica ◽

10.1530/acta.0.0550361 ◽

1967 ◽

Vol 55 (2) ◽

pp. 361-368 ◽

Cited By ~ 3

Author(s):

R. McG. Harden ◽

W. D. Alexander ◽

S. Papadopoulos ◽

M. T. Harrison ◽

S. Macfarlane

Keyword(s):

Thyroid Hormone ◽

Thyroid Function ◽

Iodine Concentration ◽

Rapid Rise ◽

Normal Range ◽

Hormone Synthesis ◽

Thyroid Hormone Synthesis ◽

Iodine Metabolism ◽

Inorganic Iodine ◽

Circulating Levels

ABSTRACT Iodine metabolism and thyroid function were studied in a patient with hypothyroidism and goitre due to dehalogenase deficiency. Initially the plasma inorganic iodine (PII) level was within the normal range but circulating levels of hormone were low and the thyroid clearance and absolute uptake of iodine (AIU) by the thyroid were high. Administration of iodide supplements resulted in a rapid rise in the plasma thyroxine concentration and restoration of the euthyroid state. Thyroid hormone synthesis appeared to proceed normally when the PII exceeded 1.0 μg/100 ml. This was achieved by increasing the intake of iodide by 612 μg per day. At PII levels around 10 μg/100 ml there was evidence of increased levels of circulating thyroid hormone.

Download Full-text