scholarly journals Molecular Basis of Thyroid Dyshormonogenesis: Genetic Screening in Population-Based Japanese Patients

2011 ◽  
Vol 96 (11) ◽  
pp. E1838-E1842 ◽  
Author(s):  
Satoshi Narumi ◽  
Koji Muroya ◽  
Yumi Asakura ◽  
Masanori Aachi ◽  
Tomonobu Hasegawa
Keyword(s):  
Single Gene ◽  
Population Based ◽  
Single Amino Acid ◽  
Thyroid Peroxidase ◽  
Loss Of Function ◽  
Phenotypic Spectrum ◽  
Thyroid Hormone Biosynthesis ◽  
Thyroid Dyshormonogenesis ◽  
Functional Snp

Abstract Context: Inborn errors of thyroid hormone biosynthesis are collectively referred to as thyroid dyshormonogenesis (DH). Seven genes have been implicated in DH, including the dual oxidase 2 gene (DUOX2), the thyroglobulin gene (TG), and the thyroid peroxidase gene (TPO). Objective: We aimed to define the prevalence and phenotypic spectrum of DH with single gene mutations. Subjects and Methods: A population-based cohort of 102 patients with permanent congenital hypothyroidism was enrolled. Fourteen were diagnosed as DH and were analyzed for the seven causative genes including DUOX2, TG, and TPO. Several common mutations were screened in the remaining 88 patients. Pathogenicity of single amino acid mutations was verified in vitro. Results: We identified four, five, and two patients with seemingly biallelic mutations in DUOX2, TG, and TPO, respectively. We also found two patients having one heterozygous DUOX2 mutation and one uncommon single-nucleotide polymorphism (SNP) p.H678R (rs57659670, allele frequency 0.035) and another two patients with homozygous p.H678R. Expression experiments and RT-PCR revealed that p.H678R is a functional SNP with theoretical 40% loss of function, supporting a role of p.H678R in the onset of DH. As for clinical phenotypes, patients with inactive DUOX2 alleles (mutations and/or p.H678R) showed characteristic time-dependent improvement of thyroid function and morphology. All three evaluated patients had a negative result in the perchlorate test. Conclusions: Mutations (or a functional SNP) in DUOX2, TG, or TPO were observed in 93% (95% confidence interval = 70–99%) of DH patients. Inactive DUOX2 alleles cause a broader phenotypic spectrum than currently accepted.

scholarly journals Differences in a Single Extracellular Residue Underlie Adhesive Functions of Two Zebrafish Aqp0s

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 2005
Author(s):  
Irene Vorontsova ◽  
James E. Hall ◽  
Thomas F. Schilling ◽  
Noriaki Nagai ◽  
Yosuke Nakazawa
Keyword(s):  
Cell Adhesion ◽  
Single Amino Acid ◽  
Amino Acid Difference ◽  
Adhesion Assay ◽  
Loss Of Function ◽  
Adhesive Properties ◽  
The Difference ◽  
In Vitro Adhesion ◽  
Cell To Cell Adhesion

Aquaporin 0 (AQP0) is the most abundant lens membrane protein, and loss of function in human and animal models leads to cataract formation. AQP0 has several functions in the lens including water transport and adhesion. Since lens optics rely on strict tissue architecture achieved by compact cell-to-cell adhesion between lens fiber cells, understanding how AQP0 contributes to adhesion would shed light on normal lens physiology and pathophysiology. We show in an in vitro adhesion assay that one of two closely related zebrafish Aqp0s, Aqp0b, has strong auto-adhesive properties while Aqp0a does not. The difference appears to be largely due to a single amino acid difference at residue 110 in the extracellular C-loop, which is T in Aqp0a and N in Aqp0b. Similarly, P110 is the key residue required for adhesion in mammalian AQP0, highlighting the importance of residue 110 in AQP0 cell-to-cell adhesion in vertebrate lenses as well as the divergence of adhesive and water permeability functions in zebrafish duplicates.

scholarly journals Development of a Single-Gene, Signature-Tag-Based Approach in Combination with Alanine Mutagenesis To Identify Listeriolysin O Residues Critical for theIn VivoSurvival of Listeria monocytogenes

2012 ◽  
Vol 80 (6) ◽  
pp. 2221-2230 ◽  
Author(s):  
Jody A. Melton-Witt ◽  
Susannah L. McKay ◽  
Daniel A. Portnoy
Keyword(s):  
Listeria Monocytogenes ◽  
Single Gene ◽  
Saturation Mutagenesis ◽  
Single Amino Acid ◽  
Screening Methods ◽  
Listeriolysin O ◽  
Phenotypic Analysis ◽  
Content Type

ABSTRACTListeriolysin O (LLO) is a pore-forming toxin of the cholesterol-dependent cytolysin (CDC) family and a primary virulence factor of the intracellular pathogenListeria monocytogenes. LLO mediates rupture of phagosomal membranes, thereby releasing bacteria into the growth-permissive host cell cytosol. Several unique features of LLO allow its activity to be precisely regulated in order to facilitate phagosomal escape, intracellular growth, and cell-to-cell spread. To improve our understanding of the multifaceted contribution of LLO to the pathogenesis ofL. monocytogenes, we developed a screen that combined saturation mutagenesis and signature tags, termedinvivoanalysis bysaturation mutagenesis andsignature tags (IVASS). We generated a library of LLO mutant strains, each harboring a single amino acid substitution and a signature tag, by using the previously described pPL2 integration vector. The signature tags acted as molecular barcodes, enabling high-throughput, parallel analysis of 40 mutants in a single animal and identification of attenuated mutants by negative selection. Using the IVASS technique we were able to screen over 90% of the 505 amino acids present in LLO and identified 60 attenuated mutants. Of these, 39 LLO residues were previously uncharacterized and potentially revealed novel functions of the toxin during infection. The mutants that were subsequently analyzedin vivoeach conferred a 2- to 4-orders of magnitude loss in virulence compared to wild type, thereby validating the screening methods. Phenotypic analysis of the LLO mutant library using commonin vitrotechniques suggested that the functional contributions of some residues could only have been revealed throughin vivoanalysis.

scholarly journals Inherited IL-18BP deficiency in human fulminant viral hepatitis

2019 ◽  
Vol 216 (8) ◽  
pp. 1777-1790 ◽  
Author(s):  
Serkan Belkaya ◽  
Eleftherios Michailidis ◽  
Cecilia B. Korol ◽  
Mohammad Kabbani ◽  
Aurélie Cobat ◽  
...  
Keyword(s):  
Viral Hepatitis ◽  
Cell Activation ◽  
Hepatitis A Virus ◽  
Nk Cell ◽  
Single Gene ◽  
Loss Of Function ◽  
Homozygous State ◽  
Inborn Errors ◽  
Fulminant Viral Hepatitis

Fulminant viral hepatitis (FVH) is a devastating and unexplained condition that strikes otherwise healthy individuals during primary infection with common liver-tropic viruses. We report a child who died of FVH upon infection with hepatitis A virus (HAV) at age 11 yr and who was homozygous for a private 40-nucleotide deletion in IL18BP, which encodes the IL-18 binding protein (IL-18BP). This mutation is loss-of-function, unlike the variants found in a homozygous state in public databases. We show that human IL-18 and IL-18BP are both secreted mostly by hepatocytes and macrophages in the liver. Moreover, in the absence of IL-18BP, excessive NK cell activation by IL-18 results in uncontrolled killing of human hepatocytes in vitro. Inherited human IL-18BP deficiency thus underlies fulminant HAV hepatitis by unleashing IL-18. These findings provide proof-of-principle that FVH can be caused by single-gene inborn errors that selectively disrupt liver-specific immunity. They also show that human IL-18 is toxic to the liver and that IL-18BP is its antidote.

scholarly journals Genetics of Congenital Isolated TSH Deficiency: Mutation Screening of the Known Causative Genes and a Literature Review

2019 ◽  
Vol 104 (12) ◽  
pp. 6229-6237 ◽  
Author(s):  
Chiho Sugisawa ◽  
Tetsuya Takamizawa ◽  
Kiyomi Abe ◽  
Tomonobu Hasegawa ◽  
Kentaro Shiga ◽  
...  
Keyword(s):  
Literature Review ◽  
Single Gene ◽  
Mutation Screening ◽  
Gene Mutations ◽  
Serum Prolactin ◽  
Loss Of Function ◽  
Mutation Carriers ◽  
Tsh Levels ◽  
Tsh Deficiency

Abstract Context Congenital isolated TSH deficiency (i-TSHD) is a rare form of congenital hypothyroidism. Five genes (IGSF1, IRS4, TBL1X, TRHR, and TSHB) responsible for the disease have been identified, although their relative frequencies and hypothalamic/pituitary unit phenotypes have remained to be clarified. Objectives To define the relative frequencies and hypothalamic/pituitary unit phenotypes of congenital i-TSHD resulting from single gene mutations. Patients and Methods Thirteen Japanese patients (11 boys and 2 girls) with congenital i-TSHD were enrolled. IGSF1, IRS4, TBL1X, TRHR, and TSHB were sequenced. For a TBL1X mutation (p.Asn382del), its pathogenicity was verified in vitro. For a literature review, published clinical data derived from 74 patients with congenital i-TSHD resulting from single-gene mutations were retrieved and analyzed. Results Genetic screening of the 13 study subjects revealed six mutation-carrying patients (46%), including five hemizygous IGSF1 mutation carriers and one hemizygous TBL1X mutation carrier. Among the six mutation carriers, one had intellectual disability and the other one had obesity, but the remaining four did not show nonendocrine phenotypes. Loss of function of the TBL1X mutation (p.Asn382del) was confirmed in vitro. The literature review demonstrated etiology-specific relationship between serum prolactin (PRL) levels and TRH-stimulated TSH levels with some degree of overlap. Conclusions The mutation screening study covering the five causative genes of congenital i-TSHD was performed, showing that the IGSF1 defect was the leading genetic cause of the disease. Assessing relationships between serum PRL levels and TRH-stimulated TSH levels would contribute to predict the etiologies of congenital i-TSHD.

scholarly journals Two novel missense mutations in the thyroid peroxidase gene, R665W and G771R, result in a localization defect and cause congenital hypothyroidism

2002 ◽  
pp. 491-498 ◽  
Author(s):  
K Umeki ◽  
T Kotani ◽  
J Kawano ◽  
T Suganuma ◽  
I Yamamoto ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Congenital Hypothyroidism ◽  
Cellular Localization ◽  
Thyroid Peroxidase ◽  
Missense Mutations ◽  
Thyroid Hormone Biosynthesis ◽  
Thyroid Dyshormonogenesis ◽  
Hormone Biosynthesis ◽  
Iodide Organification Defect ◽  
Organification Defect

OBJECTIVE: Thyroid peroxidase (TPO) deficiency is one of the causes of thyroid dyshormonogenesis, because TPO plays a key role in thyroid hormone biosynthesis. To determine the frequency and pattern of TPO abnormalities, we have been screening TPO genes of patients with congenital goitrous hypothyroidism. SUBJECTS AND METHODS: TPO genes of a patient with congenital goitrous hypothyroidism and her parents were directly sequenced, and two novel missense mutations (R665W and G771R) were found. The former was derived from her father and the latter from her mother. R665 and G771 were well conserved in the peroxidase superfamily. When mRNAs containing each of the mutations were transfected into CHO-K1 cells, each cell showed faint TPO enzyme activity. However, immunofluorescence and immunoelectron microscopic analyses revealed that neither of the mutated TPOs reached the plasma membrane. CONCLUSIONS: Two novel missense mutations in the TPO gene were found. TPO proteins encoded by these mutated alleles showed abnormal cellular localization; namely, localization on the plasma membrane was disturbed. The loss of plasma membrane localization in mutated TPOs brought about the iodide organification defect, which was diagnosed as congenital hypothyroidism.

scholarly journals Delineating the molecular and phenotypic spectrum of the SETD1B-related syndrome

2021 ◽  
Author(s):  
Marjolein J. A. Weerts ◽  
Kristina Lanko ◽  
Francisco J. Guzmán-Vega ◽  
Adam Jackson ◽  
Reshmi Ramakrishnan ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Developmental Delay ◽  
Neurodevelopmental Disorder ◽  
Epileptic Activity ◽  
Language Delay ◽  
Global Developmental Delay ◽  
Sequence Variants ◽  
Loss Of Function ◽  
Phenotypic Spectrum

Abstract Purpose Pathogenic variants in SETD1B have been associated with a syndromic neurodevelopmental disorder including intellectual disability, language delay, and seizures. To date, clinical features have been described for 11 patients with (likely) pathogenic SETD1B sequence variants. This study aims to further delineate the spectrum of the SETD1B-related syndrome based on characterizing an expanded patient cohort. Methods We perform an in-depth clinical characterization of a cohort of 36 unpublished individuals with SETD1B sequence variants, describing their molecular and phenotypic spectrum. Selected variants were functionally tested using in vitro and genome-wide methylation assays. Results Our data present evidence for a loss-of-function mechanism of SETD1B variants, resulting in a core clinical phenotype of global developmental delay, language delay including regression, intellectual disability, autism and other behavioral issues, and variable epilepsy phenotypes. Developmental delay appeared to precede seizure onset, suggesting SETD1B dysfunction impacts physiological neurodevelopment even in the absence of epileptic activity. Males are significantly overrepresented and more severely affected, and we speculate that sex-linked traits could affect susceptibility to penetrance and the clinical spectrum of SETD1B variants. Conclusion Insights from this extensive cohort will facilitate the counseling regarding the molecular and phenotypic landscape of newly diagnosed patients with the SETD1B-related syndrome.

scholarly journals The Coexistence of a Novel Inactivating Mutant Thyrotropin Receptor Allele with Two Thyroid Peroxidase Mutations: A Genotype-Phenotype Correlation

2011 ◽  
Vol 96 (6) ◽  
pp. E1001-E1006 ◽  
Author(s):  
Chutintorn Sriphrapradang ◽  
Yardena Tenenbaum-Rakover ◽  
Mia Weiss ◽  
Marla S. Barkoff ◽  
Osnat Admoni ◽  
...  
Keyword(s):  
Clinical Investigation ◽  
Gene Mutations ◽  
Structure And Function ◽  
Compound Heterozygote ◽  
Thyroid Peroxidase ◽  
Thyrotropin Receptor ◽  
Loss Of Function ◽  
Phenotype Correlation ◽  
And Function

Context: TSH receptor (TSHR) and thyroid peroxidase (TPO) gene mutations occur independently. This is the first report of their coexistence in the same individuals. Objectives: The objective of the study was to evaluate the genotype-phenotype correlations when mutations in both genes are present alone or together in the same individual. Patients and Methods: Thirty subjects from an extended Arab kindred underwent clinical investigation and molecular studies of the mutant TSHRs. Results: A novel mutant TSHR was identified, involving four nucleotides at three sites on the same allele, c.267G>T (L89L), c.269/270AG>CT (Q90P), and c.790C>T (P264S). In addition, two known TPO gene mutations, G493S and R540X, were identified. Thirteen heterozygotes for the mutant TSHR allele had mild hyperthyrotropinemia. In nine of theses, the coexistence of a TPO mutation in one allele did not magnify the hyperthyrotropinemia. Homozygotes for the mutant TSHR and a compound heterozygote for the TPO mutations presented frank hypothyroidism. In vitro studies showed increasing loss of function for Q90P less than P264S less than Q90P/P264S TSHR mutants, the latter being that expressed in the subjects under investigation. The two interchangeably used WT TSHR vectors, L87 and V87, although functionally identical, differed in structure and function in the presence of the Q90P mutation. Conclusions: TSHR and TPO gene mutations were identified alone and together in individuals of a consanguineous kindred. Homozygotes for the TSHR and a compound heterozygote for the TPO mutations were hypothyroid. The mild hyperthyrotropinemia of heterozygotes for the mutant TSHR allele was not aggravated by the coexistence of a TPO defect in one allele.

scholarly journals Delineating the molecular and phenotypic spectrum of the SETD1B-related syndrome

2021 ◽  
Author(s):  
Marjolein J.A. Weerts ◽  
Kristina Lanko ◽  
Francisco J. Guzmán-Vega ◽  
Adam Jackson ◽  
Reshmi Ramakrishnan ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Developmental Delay ◽  
Neurodevelopmental Disorder ◽  
Epileptic Activity ◽  
Language Delay ◽  
Global Developmental Delay ◽  
Sequence Variants ◽  
Loss Of Function ◽  
Phenotypic Spectrum

ABSTRACTPathogenic variants in SETD1B have been associated with a syndromic neurodevelopmental disorder including intellectual disability, language delay and seizures. To date, clinical features have been described for eleven patients with (likely) pathogenic SETD1B sequence variants. We perform an in-depth clinical characterization of a cohort of 36 unpublished individuals with SETD1B sequence variants, describing their molecular and phenotypic spectrum. Selected variants were functionally tested using in vitro and genome-wide methylation assays. Our data present evidence for a loss-of-function mechanism of SETD1B variants, resulting in a core clinical phenotype of global developmental delay, language delay including regression, intellectual disability, autism and other behavioral issues, and variable epilepsy phenotypes. Developmental delay appeared to precede seizure onset, suggesting SETD1B dysfunction impacts physiological neurodevelopment even in the absence of epileptic activity. Interestingly, males are significantly overrepresented and more severely affected, and we speculate that sex-linked traits could affect susceptibility to penetrance and the clinical spectrum of SETD1B variants. Finally, despite the possibility of non-redundant contributions of SETD1B and its paralogue SETD1A to epigenetic control, the clinical phenotypes of the related disorders share many similarities, indicating that elucidating shared and divergent downstream targets of both genes will help to understand the mechanism leading to the neurobehavioral phenotypes. Insights from this extensive cohort will facilitate the counseling regarding the molecular and phenotypic landscape of newly diagnosed patients with the SETD1B-related syndrome.

scholarly journals Functional Analysis of Thyroid Peroxidase Gene Mutations Detected in Patients with Thyroid Dyshormonogenesis

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Srikanta Guria ◽  
Biswabandhu Bankura ◽  
Nisha Balmiki ◽  
Arup Kumar Pattanayak ◽  
Tapas Kumar Das ◽  
...  
Keyword(s):  
West Bengal ◽  
Clinical Manifestations ◽  
Gene Mutations ◽  
Thyroid Peroxidase ◽  
Normal Individuals ◽  
Screening Protocol ◽  
Pcr Products ◽  
Key Enzyme ◽  
Thyroid Dyshormonogenesis

Thyroid peroxidase (TPO) is the key enzyme in the biosynthesis of thyroid hormones. We aimed to identify the spectrum of mutations in theTPOgene leading to hypothyroidism in the population of West Bengal to establish the genetic etiology of the disease. 200 hypothyroid patients (case) and their corresponding sex and age matched 200 normal individuals (control) were screened depending on their clinical manifestations. Genomic DNA was isolated from peripheral blood samples andTPOgene (Exon 7 to Exon 14) was amplified by PCR. The PCR products were subjected to sequencing to identify mutations. Single nucleotide changes such as Glu 641 Lys, Asp 668 Asn, Thr 725 Pro, Asp 620 Asn, Ser 398 Thr, and Ala 373 Ser were found. Changes in the TPO were assayedin vitroto compare mutant and wild-type activities. Five mutants were enzymatically inactive in the guaiacol and iodide assays. This is a strong indication that the mutations are present at crucial positions of theTPOgene, resulting in inactivated TPO. The results of this study may help to develop a genetic screening protocol for goiter and hypothyroidism in the population of West Bengal.

scholarly journals ALG9 Mutation Carriers Develop Kidney and Liver Cysts

2019 ◽  
Vol 30 (11) ◽  
pp. 2091-2102 ◽  
Author(s):  
Whitney Besse ◽  
Alex R. Chang ◽  
Jonathan Z. Luo ◽  
William J. Triffo ◽  
Bryn S. Moore ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Kidney Disease ◽  
Population Based ◽  
Carrier State ◽  
Disease Genes ◽  
Loss Of Function ◽  
Polycystic Kidney ◽  
Whole Exome ◽  
Autosomal Dominant Polycystic Kidney

BackgroundMutations in PKD1 or PKD2 cause typical autosomal dominant polycystic kidney disease (ADPKD), the most common monogenic kidney disease. Dominantly inherited polycystic kidney and liver diseases on the ADPKD spectrum are also caused by mutations in at least six other genes required for protein biogenesis in the endoplasmic reticulum, the loss of which results in defective production of the PKD1 gene product, the membrane protein polycystin-1 (PC1).MethodsWe used whole-exome sequencing in a cohort of 122 patients with genetically unresolved clinical diagnosis of ADPKD or polycystic liver disease to identify a candidate gene, ALG9, and in vitro cell-based assays of PC1 protein maturation to functionally validate it. For further validation, we identified carriers of ALG9 loss-of-function mutations and noncarrier matched controls in a large exome-sequenced population-based cohort and evaluated the occurrence of polycystic phenotypes in both groups.ResultsTwo patients in the clinically defined cohort had rare loss-of-function variants in ALG9, which encodes a protein required for addition of specific mannose molecules to the assembling N-glycan precursors in the endoplasmic reticulum lumen. In vitro assays showed that inactivation of Alg9 results in impaired maturation and defective glycosylation of PC1. Seven of the eight (88%) cases selected from the population-based cohort based on ALG9 mutation carrier state who had abdominal imaging after age 50; seven (88%) had at least four kidney cysts, compared with none in matched controls without ALG9 mutations.ConclusionsALG9 is a novel disease gene in the genetically heterogeneous ADPKD spectrum. This study supports the utility of phenotype characterization in genetically-defined cohorts to validate novel disease genes, and provide much-needed genotype-phenotype correlations.

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