A molecular analysis and long-term follow-up of two siblings with severe congenital hypothyroidism carrying the IVS30+1G>T intronic thyroglobulin mutation

Abstract

Objective: To extend the molecular analysis of the IVS30+1G>T intronic thyroglobulin (TG) mutation, and to report the eleven year follow-up of the affected patients. Methods: Two siblings with severe congenital hypothyroidism with fetal and neonatal goiter, harboring the IVS30+1G>T mutation were included. Nodular and non-nodular thyroid tissue specimens were collected. Specifi c thyroid genes expression was evaluated by real-timePCR and by immunohistochemistry. Results: In non-nodular tissue specifi c thyroid genes mRNA were reduced when compared to normal thyroid sample. In the nodule, TPO and NIS expression was very low. Microscopic examinations showed very large follicular-lumina and swollen vesicles of endoplasmatic-reticulum. Strong cytoplasmatic and low follicular-lumen TG immunostaining were detected. Intracellular NIS, membrane TPO and TSHR immunostaining had higher positivity in nonnodular sample. Both patients had a long-term adequate developmental outcome, besides one patient have been lately-treated. Conclusions: IVS30+1G>T mutation not only lead to very enlarge endoplasmatic-reticulum, but also to alterations of specifi c thyroid genes expression. The clinical evolution of patients harboring these mutations strengthen the concept of the infl uence of environment, like iodine nutrition, to determine the fi nal phenotypic appearance. RESUMO Análise Molecular e Acompanhamento a Longo Prazo de Dois Irmãos com Hipotireoidismo Congênito Portadores da Mutação Intrônica IVS30+1G>T noGene da Tireoglobulina. Objetivo: Aprofundar a análise molecular da mutação intrônica IVS30+1G>T do gene tireoglobulina (TG) e relatar a clínica de pacientes portadores da mutação, acompanhados por 11 anos. Métodos: Foram estudados dois irmãos com hipotireoidismo congênito grave com bócio fetal e bócio neonatal, portadores da mutação IVS30+1G>T. Foram coletadas amostras de tecido nodular e não-nodular. Avaliou-se a expressão de genes específi cos da tireóide por PCR em tempo real e imunohistoquímica. Resultados: A expressão de genes específi -cos da tireóide foi menor no tecido não-nodular que no tecido normal controle. Expressões de TPO e NIS foram extremamente baixas no tecido nodular. Verifi cou-se lúmen folicular aumentado com grandes vesículas de retículo endoplasmático, e detectou-se forte marcação de TG no citoplasma e fraca no lúmen folicular. No tecido não-nodular observou-se forte positividade de NIS intracelular e, TPO e TSHR na membrana plasmática. O acompanhamento em longo prazo dos pacientes mostrou adequado desenvolvimento, apesar de um deles ter recebido tratamento tardio. Conclusões: A mutação IVS30+1G>T não só promove alterações no retículo endoplasmático, como alterações na expressão de genes específi cos da tireóide. A evolução clínica destes pacientes reforça o conceito da infl uência do meio ambiente, como o aporte nutricional de iodo, no fenótipo fi nal.

Case Report: Functional Analysis and Neuropsychological Evaluation of Dyshormonogenetic Fetal Goiter in Siblings Caused by Novel Compound Hyterozygous TPO Gene Mutations

“…They showed good adherence to LT4 treatment and adequate hormonal status along with the increase of the LT4 dose. Previous studies have also shown normal growth development of fetal goiter patients under adequate treatment (15,21).…”

“…Up to now, mutations in TG, TPO, NIS, and DUOXA2 have been identified in few dyshormonogenetic fetal goiter patients (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28) as shown in Supplementary Table 1. These mutations are usually transmitted in an autosomal recessive fashion; however, some studies have reported monoallelic mutations (29).…”

Do Different Species of Sargassum in Haizao Yuhu Decoction Cause Different Effects in a Rat Goiter Model?

“…NIS, TPO, and Tg are critical to the synthesis of thyroid hormones. Genetic abnormalities in any of these substances can cause diseases such as goiter, hypothyroidism, and autoimmune manifestations [18–20]. We observed that the mRNA expression of TPO and Tg was low in the Mod group, whereas the mRNA expression of NIS was high.…”

A novel mutation in intron 11 donor splice site, responsible of a rare genotype in thyroglobulin gene by altering the pre-mRNA splincing process. Cell expression and bioinformatic analysis

“…In particular, a missplicing of TG pre-mRNA due to a mutation in consensus donor or acceptor ss is known to induce a congenital goiter and hypothyroidism in humans. Exon skipping in the human TG gene can be caused by nucleotide Alzahrani et al, 2006;Bruellman et al, 2020b;Chen et al, 2018;Citterio et al, 2015, de Filippis et al, 2017Fu et al, 2016a, Gutnisky et al, 2004Hermanns et al, 2013Hu et al, 2016, Ieiri et al 1991Makretskaya et al, 2018;Medeiros-Neto et al, 1996;Narumi et al, 2011;Nicholas et al, 2016;Niu et al, 2009;Pardo et al, 2008Pardo et al, , 2009Peteiro-Gonzalez et al, 2010;Rubio et al, 2008;Targovnik et al, 1995Targovnik et al, , 2001Targovnik et al, , 2012Watanabe et al, 2019;Zou et al, 2018]. The usefulness of splicing reporter minigene assays has been shown to be a good approach to determine the effect of the variants on the splicing process [Bonnet et al, 2008;Tournier et al, 2008] when is difficult to obtain RNA from patients' tissues.…”