Browsing by Author "Timothy Barrett, Timothy"

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    A deletion including exon 2 of the TSHR gene is associated with thyroid dysgenesis and severe congenital hypothyroidism
    (Walter De Gruyter Gmbh, 2014-07) Cangül, Hakan; Schoenmakers, Nadia A.; Saǧlam, Yaman; Kendall, Michaela; Timothy Barrett, Timothy; Chatterjee, Krish; Mäher, Eamonn Richard; Saǧlam, Halil; Doğanlar, Durmuş; Eren, Erdal; Tarım, Ömer Faruk; Uludağ Üniversitesi/Tıp Fakültesi/Çocuk Endokrinoloji Anabilim Dalı.; 0000-0003-0710-5422; 0000-0002-1684-1053; C-7392-2019; AAH-1155-2021; 35612700100; 56363214600; 36113153400; 6701427186
    Congenital hypothyroidism (CH) is the most common neonatal endocrine disorder and 2% of cases have a familial origin. Our aim in this study was to determine the genetic alterations in two siblings with CH coming from a consanguineous family. As CH is often inherited in an autosomal recessive manner in consanguineous/multi case-families, we first performed genetic linkage studies to all known causative CH loci followed by conventional sequencing of the linked gene. The family showed potential linkage to the TSHR locus and our attempts to amplify and sequence exon 2 of the TSHR gene continuously failed. Subsequent RT-PCR analysis using mRNA and corresponding cDNA showed a large deletion including the exon 2 of the gene. The deletion was homozygous in affected cases whilst heterozygous in carrier parents. Here we conclude that CH in both siblings of this study originates from a large deletion including the exon 2 of the TSHR gene. This study demonstrates that full sequence analysis in a candidate CH gene might not always be enough to detect genetic alterations, and additional analyses such as RT-PCR and MLPA might be necessary to describe putative genetic causes of the disease in some cases. It also underlines the importance of detailed molecular genetic studies in the definitive diagnosis and classification of CH.
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    Novel TSHR mutations in consanguineous families with congenital nongoitrous hypothyroidism
    (Wiley, 2010-11) Morgan, Neil V.; Forman, Julia R.; Aycan, Zehra; Böber, Ece; Cesur, Yaşar; Kirby, Gail A.; Pasha, Shanaz S.; Çetinkaya, Semra Çağlar; Baş, Veysel Nihat; Demir, Korcan; Yuca, Sevil Arı; Meyer, Esther; Högler, Wolfgang; Timothy Barrett, Timothy; Mäher, Eamonn Richard; Cangül, Hakan; Sağlam, Halil; Yakut, Tahsin; Gülten, Tuna; Tarım, Ömer Faruk; Karkucak, Mutlu; Eren, Erdal; Kendall, Michaela; Uludağ Üniversitesi/Tıp Fakültesi/Tıbbi Genetik Anabilim Dalı.; Uludağ Üniversitesi/Tıp Fakültesi/Çocuk Sağlığı ve Hastalıkları Anabilim Dalı.; Uludağ Üniversitesi/Tıp Fakültesi/Halk Sağlığı Anabilim Dalı.; 0000-0003-0710-5422; 0000-0002-1684-1053; C-7392-2019; AAM-1734-2020; 8911611600; 35612700100; 6602802424; 6505944216; 6701427186; 35388323500; 36113153400; 8062516400
    Objective Nonsyndromic autosomal recessively inherited non-goitrous congenital hypothyroidism (CHNG) can be caused by mutations in TSHR, PAX8, TSHB and NKX2-5. We aimed to investigate mutational frequencies of these genes and genotype/phenotype correlations in consanguineous families with CHNG. Design Because consanguinity in individuals with a presumptive genetic condition is often an indicator of an autosomal recessive inheritance and allows firmer correlations to be established between genotype and phenotype, we planned to execute our study in consanguineous families. Patients Hundred and thirty-nine children with CHNG phenotype born to consanguineous families. Measurements First, we investigated cases for evidence of linkage to the four known CHNG genes by microsatellite marker analysis. Mutation analysis by direct sequencing was then performed in those cases in whom linkage to the relevant candidate gene could not be excluded. In addition, in silico analysis of the predicted structural effects of TSHR mutations was performed and related to the mutation-specific disease phenotype. Results Homozygous germline TSHR mutations were detected in six families (5%), but no mutations were detected in PAX8, TSHB and NKX2-5. Four of TSHR mutations had not previously been described. Genotype-phenotype correlations were established and found to be related to the predicted structural effects of the mutations. Conclusions Known causative genes account for the development of CHNG only in a minority of cases, and our cohort should provide a powerful resource to identify novel causative genes and to delineate the extent of locus heterogeneity in autosomal recessively inherited CHNG.