Growth and development in a child with resistance to thyroid hormone and ectopic thyroid gland

Concurrent THRB and DUOX2 variants in a patient detected via newborn screening for congenital hypothyroidism: a case of resistance to thyroid hormone

Most patients with resistance to thyroid hormone (RTH) test negative in newborn screening (NBS) for congenital hypothyroidism (CH). Here, we present a case of RTH diagnosed through NBS. The patient presented to us after her NBS for CH revealed high TSH (23.4 µIU/mL) and free T4 (FT4) (5.40 ng/dL) levels. Apart from tachycardia, she exhibited no other manifestations related to excess or deficiency of thyroid hormones. A confirmatory test replicated the findings, showing elevated serum TSH levels (35.7 µIU/mL) along with high FT4 levels (5.84 ng/dL). Ultrasonography showed marked thyroid gland enlargement (> +4 SD). Targeted next-generation sequencing of genes associated with genetic thyroid disorders revealed a previously reported THRB variant, p.Gly345Cys. Unexpectedly, two biallelic DUOX2 variants (p.His678Arg and p.Arg1334Trp) were also detected. At her last visit, no significant issues were observed with neurological development, growth, bone maturation, or gastrointestinal symptoms related to thyroid function at the age of 1 year, without treatment for RTH and CH. During follow-up, the TSH and FT4 levels gradually decreased. In conclusion, we report a patient with simultaneous RTH and DUOX2 defects, demonstrating the value of conducting a comprehensive analysis of multiple genes associated with thyroid diseases to better comprehend the pathogenesis in patients with atypical thyroid-related phenotypes.

Tissue sensitivity to thyroid hormones may change over time

INTRODUCTION

Patients with congenital hypothyroidism (CH) may transiently show a certain degree of pituitary resistance to levothyroxine (LT4) which, however, normalizes subsequently. However, in some individuals, thyroid-stimulating hormone (TSH) fails to normalize despite adequate LT4 treatment.

METHODS

Nine patients with CH followed in three Academic Centre who developed over time resistance to thyroid hormones underwent extensive biochemical and genetic analyses. These latter were performed by Sanger sequence or targeted next-generation sequencing technique including a panel of candidate genes involved in thyroid hormone actions and congenital hypothyroidism (CH): THRA, THRB, DIO1, DIO2, SLC16A2, SECISBP2, DUOX2, DUOXA2, FOXE1, GLIS3, IYD, JAG1, NKX2-1, NKX2- 5, PAX8, SLC26A4, SLC5A5, TG, TPO, TSHR.

RESULTS

All patients displayed a normal sensitivity to thyroid hormone (TH) in the first years of life but developed variable degrees of resistance to LT4 treatment at later stages. In all cases, TSH normalized only in the presence of high free thyroxine levels. Tri-iodothyronine suppression test followed by thyrotrophin-releasing hormone stimulation was performed in two cases and was compatible with central resistance to THs. This biochemical feature was present independently on the cause of CH, being observed either in patients with an ectopic (n = 2) or eutopic gland (n = 3) or in case of athyreosis (n = 1). None of the patients had genetic variants in genes involved in the regulation of TH actions, while in two cases, we found two double heterozygous missense variants in TSHR and GLIS3 or in DUOX2 and SLC26A4 genes, respectively.

CONCLUSIONS

We report CH patients who showed an acquired and unexplainable pituitary refractoriness to TH action.

Resistance to Thyroid Hormone Beta: A Focused Review

Resistance to thyroid hormone (RTH) is a clinical syndrome defined by impaired sensitivity to thyroid hormone (TH) and its more common form is caused by mutations in the thyroid hormone receptor beta (THRB) gene, termed RTHβ. The characteristic biochemical profile is that of elevated serum TH levels in absence of thyrotropin suppression. Although most individuals are considered clinically euthyroid, there is variability in phenotypic manifestation among individuals harboring different THRB mutations and among tissue types in the same individual due in part to differential expression of the mutant TRβ protein. As a result, management is tailored to the specific symptoms of TH excess or deprivation encountered in the affected individual as currently there is no available therapy to fully correct the TRβ defect. This focused review aims to provide a concise update on RTHβ, discuss less well recognized associations with other thyroid disorders, such as thyroid dysgenesis and autoimmune thyroid disease, and summarize existing evidence and controversies regarding the phenotypic variability of the syndrome. Review of management addresses goiter, attention deficit disorder and "foggy brain". Lastly, this work covers emerging areas of interest, such as the relevance of variants of unknown significance and novel data on the epigenetic effect resulting from intrauterine exposure to high TH levels and its transgenerational inheritance.

The placenta as a window to the brain: A review on the role of placental markers in prenatal programming of neurodevelopment

BACKGROUND

During development, the placenta can be said to be the most important organ, however, the most poorly researched. There is currently a broader understanding of how specific insults during development affect the fetal brain, and also the importance of placental signaling in neurodevelopmental programming. Epigenetic responses to maternal and fetal signals are an obvious candidate for transforming early life inputs into long-term programmatic outcomes. As a mediator of maternal and environmental signals to the developing fetus, epigenetic processes within the placenta are particularly powerful such that alterations of placental gene expression, downstream function, and signalling during foetal development have the potential for dramatic changes in developmental programming.

SUMMARY

In this article, we reviewed emerging evidence for a placental role in prenatal neurodevelopmental programming with a specific focus on nutrient and prenatal stress signals integration into chromatin changes; this new understanding, we hope will provide the means for lowering developmentally based disorder risk, and new therapeutic targets for treatment in adulthood.

KEY MESSAGES

Based on this review, the placenta is a potent micro-environmental player in neurodevelopment as it orchestrates a series of complex maternal-foetal interactions. Maternal insults to this microenvironment will impair these processes and disrupt foetal brain development resulting in the prenatal programming of neurodevelopmental disorders. These findings should inspire advance animal model and human research drive to appraise gene-environment impacts during pregnancy that will target the developmental cause of adult-onset mental disorders.

Coexistence of resistance to thyroid hormone and ectopic thyroid: ten-year follow-up

Resistance to thyroid hormone (RTH) coexisting with ectopic thyroid is rare. Here we report a case of RTH with ectopic thyroid. A ten-year-old girl had been misdiagnosed as congenital hypothyroidism and treated with levothyroxine since she was born. Ten-year follow-up showed that the elevated thyrotropin was never suppressed by levothyroxine and no signs indicating hyperthyroidism or hypothyroidism despite elevated FT3 and FT4 levels. Therefore the girl developed no defects in physical and cognitive development. Pituitary adenoma was excluded by magnetic resonance imaging. Ultrasonography did not find the thyroid gland in the normal place, while the thyroid scan found a large lingual thyroid gland. The octreotide inhibition test showed a reduction in thyrotropin by 41.98%. No mutation was detected in the thyroid hormone receptor (THR) β, THRα, thyrotropin receptor (TSHR), and GNAS1 genes. To our knowledge, it is an interesting RTH case coexisting with lingual thyroid.