Thyroid hormone resistance syndrome caused by heterozygous A317T mutation in thyroid hormone receptor β gene: Report of one Chinese pedigree and review of the literature

Thyroid hormone resistance syndrome due to a novel heterozygous mutation and concomitant Hashimoto's Thyroiditis: A pedigree report

Thyroid hormone resistance syndrome (THRS) is a rare disease characterized by reduced sensitivity to thyroid hormones. Mutations in the thyroid hormone receptor beta (THRB) gene are considered as contributing to the pathogenesis. This report describes a Chinese pedigree with THRS and Hashimoto’s thyroiditis (HT) due to novel point mutation in the 11th exon of the THRB gene (c. 1378 G > A). The proband complained of goitre with increased thyroid hormone and normal thyroid stimulating hormone levels. Gene sequencing was performed to confirm the diagnosis. HT was also diagnosed based on positive thyroid autoantibodies and diffuse, grid-like changes in the thyroid on ultrasound examination. Additionally, a comprehensive examination of the proband’s pedigree was conducted. The patient’s father exhibited the same gene mutation site and was diagnosed with THRS and HT. No mutation site was detected in three patients with HT only and three healthy volunteers. Thus, gene sequencing should be considered the gold standard for diagnosing THRS. Furthermore, treatment should be individualized to control the patient’s symptoms rather than normalizing thyroid hormone levels. Further studies that determine the relationship between THRS and TH are warranted.

Case Report

BACKGROUND

Thyroid hormone resistance (RTH) is defined as a decrease in response to thyroid hormones in the target tissue. Most patients present with nonspecific findings. In this article, we aimed to represent a 22-year-old female patient who presented with palpitation, fatigue, and heat intolerance. She was thought to have thyroid hormone resistance and her genetic examination revealed NM_001128177.1 (THRβ): c.1034G > A (p.Gly345Asp) pathogenic variation in the THRβ gene.

CASE REPORT

A 22-year-old female patient presented with complaints of fatigue, heat intolerance and palpitations. She was taking Propranolol twice daily at admission. Her family history revealed hypothyroidism in her grandmother. Her physical examination results were as follows: height 160 cm, weight 65 kg, body mass index 25.4kg/m², body temperature 36.5°C, respiratory rate 18/min, heart rate 86 beats/min, blood pressure 120/80 mmHg. Her palms were sweaty. The heart sounds were normal, and no heart murmur was auscultated. The laboratory results were TSH: 5.31uU/mL, fT3: 6.83 pg/mL, and fT4: 2.43 ng/dL. THRβ gene mutation analysis was requested for our patient whose clinical history and laboratory results were compatible with thyroid hormone resistance. The pathogenic variation NM_001128177.1(THRβ):c.1034G>A (p.Gly345Asp) was detected after analysis.

CONCLUSION

A diagnosis of RTH requires high clinical suspicion and a genetic mutation analysis should be requested in the case of clinical suspicion. In this way, unnecessary anti-thyroid treatment can be prevented.

Update on resistance to thyroid hormone syndromeβ

Resistance to thyroid hormone syndrome (RTH) is an autosomal dominant or recessive genetic disease caused by mutation of either the thyroid hormone receptorβ (THR-β) gene or the thyroid hormone receptorα (THR-α) gene. RTH due to mutations of the THR-β gene (hereafter, RTH-β) is characterized by a decreased response of the target tissue to thyroid hormone, increased serum levels of free triiodothyronine (FT3) and/or free thyroxine (FT4), and inappropriate secretion of thyroid-stimulating hormone (TSH, normal or elevated). Clinical manifestations of RTH-β vary from hyperthyroidism to hypothyroidism or simple goiter, and RTH-β is often misdiagnosed clinically. The present review was prepared for the purpose of expanding knowledge of RTH-β in order to reduce the rate of misdiagnosis.

Hypothyroidism and hyperthyroidism

Congenital hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormones. It occurs in 1:2000-4000 newborns. Common clinical features include decreased activity and increased sleep, feeding difficulty, constipation, prolonged jaundice, myxedematous facies, large fontanels (especially posterior), macroglossia, distended abdomen with umbilical hernia, and hypotonia. Slow linear growth and developmental delay are usually apparent by 4-6 months of age. Without treatment, congenital hypothyroidism leads to severe intellectual deficit and short stature. Congenital hyperthyroidism occurs when the thyroid gland produces too much of the hormone thyroxine, which can accelerate body metabolism, causing unintentional weight loss and a rapid or irregular heartbeat. Hyperthyroidism is very rare and its prevalence is unknown. Common clinical features include unintentional weight loss, tachycardia, arrhythmia, palpitations, anxiety, tremor and sweating. Here we summarize the genes involved in congenital hypo- and hyperthyroidism and the tests we use for genetic analysis. (www.actabiomedica.it)

Genomic test ends a long diagnostic odyssey in a patient with resistance to thyroid hormones

Background

Resistance to thyroid hormones is a very rare condition, which is often misdiagnosed and mistreated. The cases where there is a concomitant autoimmune thyroid disorder are ultra-rare and particularly challenging to treat. Diagnostic and research-based genomic testing can sometimes identify pathogenic variants unrelated to the primary reason for testing (incidental findings).

Case presentation

We present a patient with thyroid resistance associated with hypothyroid Hashimoto thyroiditis. The long diagnostic odyssey spanning over 20-years included repeated misdiagnoses and mistreatments and was concluded by a research-based genomic testing, identifying a “de novo” THRB pathogenic variant. The varying sensitivity of various tissues to thyroid hormones accompanied by hypothyroid Hashimoto thyroiditis continues to pose a significant treatment challenge.

Conclusions

Thyroid hormone resistance continues to be an un(der)- and misdiagnosed thyroid condition whose management is particularly challenging when associated with autoimmune thyroid disease. Whole exome sequencing has the potential to identify THRB pathogenic variants as incidental findings. Reporting such secondary findings from genomic testing may be particularly important in the context of the rarity of the condition and the potential clinical consequences of misdiagnosis and mistreatment.

Phenotype variability and different genotype of four patients with thyroid hormone resistance syndrome due to variants in the THRB gene

BACKGROUND

  Resistance to thyroid hormone (RTH) is a rare dominantly inherited disorder mainly due to variants in the THRB gene leading to decreased end-organ responsiveness to thyroid hormones.

CASE REPORT

Clinical and molecular characteristics of four patients with RTH are described. Four patients with various phenotypes were studied; two prepubertal boys and two adults (one male and one female). Sequencing analysis of the THRB was performed. All individuals had persistently elevated free thyroxine and/or free triiodothyronine associated with non-suppressed thyroid-stimulating hormone (TSH), and all had non-autoimmune goiters of various sizes. In both adults, antithyroid drugs were previously administered without successful suppression of the thyroid hormones. The 27-year-old female had resting tachycardia as the only symptom. The 35-year-old male had a degree of cognitive impairment and was initially diagnosed with atrial fibrillation. The eight-year-old boy was diagnosed with attention deficit disorder and had resting tachycardia. The oldest boy (age nine years) underwent thyroid function tests as a part of the investigation for obesity and learning difficulties. Direct sequencing analysis of the THRB gene showed three previously reported variants: p.His435Leu (c.1304A>T) in the 35-year-old male, p.Pro453Thr (c.1357C>A) in the oldest boy, and p.Arg438Cys (c.1312C>T) variant in the other two patients.

CONCLUSIONS

Various phenotypes characterize common variants in the THRB gene, asymptomatic, thyroid hormone deprivation symptoms, or thyroid hormone excess symptoms. RTH should be suspected in both adults and children with elevated thyroid hormones and not suppressed TSH. A prompt molecular diagnosis and genetic counseling could prevent unnecessary tests and inappropriate treatments. HIPPOKRATIA 2019, 23(3): 135-139.

Thyroid hormone resistance and the value of genetics: Three case reports

RATIONAL

Thyroid hormone resistance (RTH) is a rare disease that is characterised by a lowered sensitivity of the target organs to thyroid hormone. Herein, we present 3 cases of confirmed RTH, with the support of clinical lab results and/or gene sequencing at diagnosis.

PATIENT CONCERNS

The 3 included patients were found to have elevated levels of free T3 (FT3), free T4 (FT4), and non-supressed levels of thyroid stimulating hormone (TSH).

DIAGNOSIS

All patients were tested for thyroid antibodies, somatostatin suppression, vision and hearing at diagnosis. Electrocardiography (ECG), thyroid ultrasonography, and magnet resonance imaging (MRI) of the sellar region were also performed. Furthermore, gene sequencing was used to detect the thyroid hormone receptor beta (THRB) gene mutation.

INTERVENTIONS

Patient treatment was individualised. Patients were given levothyroxine sodium or a low dose of thyroiodin, depending on the individual symptoms.

OUTCOMES

After treatment, thyroid function was stable in 2 of the teenage patients. No evidence of worsening thyrotoxicosis was observed.

LESSONS

Gene sequencing should be considered together with clinical lab results, including somatostatin suppression testing, before approaching a diagnosis of RTH.

Challenging diagnosis of thyroid hormone resistance initially as Hashimoto's thyroiditis

Background Resistance to thyroid hormone (RTH) commonly presents with goiter, attention deficit hyperactivity disorder (ADHD), short stature and tachycardia. However, due to its variable presentation with subtle clinical features, a third of the cases are mistreated, typically as hyperthyroidism. Case presentation A 15-year-old female with ADHD and oligomenorrhea was initially diagnosed as Hashimoto's thyroiditis but found to have a rare heterozygous mutation in c803 C>G (p Ala 268 Gly) in the THRβ gene, confirming resistance to thyroid hormone. Conclusions Fluctuating thyroid function tests in addition to thyroid peroxidase antibody (TPO Ab) positivity complicated the diagnosis of RTH, initially diagnosed as Hashimoto's thyroiditis. A high index of suspicion is needed to prevent misdiagnosis and mistreatment.

Thyroid Hormone Resistance in Identical Twin Sisters with Atrial Fibrillation: Case Report and Review of the Literature

AIM

To report identical twin sisters harboring the A317T mutation in the thyroid hormone beta receptor gene (TR β) who developed atrial fibrillation and refractory congestive heart failure in the sixth decade of life. To critically assess whether the A317T mutation may be responsible for increased cardiotoxicity compared to other thyroid hormone beta receptor gene mutations.

METHODS

A 59-year-old woman referred for evaluation of abnormal thyroid function tests had been experiencing frequent spells of tachycardia associated with dyspnea, and dizziness necessitating multiple hospitalizations. Elevation in free thyroxine (T4), total triiodothyronine (T3) and inappropriately normal thyroid stimulating hormone (TSH) was consistent with a clinical diagnosis of thyroid hormone resistance. Magnetic resonance imaging of the brain was negative for a TSH-secreting pituitary adenoma. A blood sample was sent for thyroid hormone receptor gene mutational analysis, but it would require eight weeks to complete processing.

RESULTS

A modified L-T3 suppression test was used to assess thyroid-pituitary axis feedback. After three weeks' of cytomel (L-T3) (25 micrograms daily) TSH decreased by 50%, and free T4 level decreased by 22% compared to baseline levels. Genetic testing revealed a heterozygous A317T mutation in the thyroid hormone beta receptor gene. Serial two-dimensional echocardiography demonstrated evolution to left atrial enlargement over a three-year period. Prior published literature suggests a less than 10% prevalence of atrial fibrillation in adults with thyroid hormone resistance harboring various TR-β gene mutations. Yet all five of five (100%) adults having the A317T mutation were reported to experience atrial fibrillation by age 50.

CONCLUSIONS

A new kindred with resistance to thyroid hormone harboring the A317T disease-causative mutation is described in which identical twin sisters had a mid-life onset of atrial fibrillation and refractory congestive heart failure.