Nonautoimmune Hyperthyroidism Research Articles

Mechanisms of thyrotropin receptor-mediated phenotype variability deciphered by gene mutations and M453T-knockin model.

The clinical spectrum of thyrotropin receptor-mediated (TSHR-mediated) diseases varies from loss-of-function mutations causing congenital hypothyroidism to constitutively active mutations (CAMs) leading to nonautoimmune hyperthyroidism (NAH). Variation at the TSHR locus has also been associated with altered lipid and bone metabolism and autoimmune thyroid diseases. However, the extrathyroidal roles of TSHR and the mechanisms underlying phenotypic variability among TSHR-mediated diseases remain unclear. Here we identified and characterized TSHR variants and factors involved in phenotypic variability in different patient cohorts, the FinnGen database, and a mouse model. TSHR CAMs were found in all 16 patients with NAH, with 1 CAM in an unexpected location in the extracellular leucine-rich repeat domain (p.S237N) and another in the transmembrane domain (p.I640V) in 2 families with distinct hyperthyroid phenotypes. In addition, screening of the FinnGen database revealed rare functional variants as well as distinct common noncoding TSHR SNPs significantly associated with thyroid phenotypes, but there was no other significant association between TSHR variants and more than 2,000 nonthyroid disease endpoints. Finally, our TSHR M453T-knockin model revealed that the phenotype was dependent on the mutation's signaling properties and was ameliorated by increased iodine intake. In summary, our data show that TSHR-mediated disease risk can be modified by variants at the TSHR locus both inside and outside the coding region as well as by altered TSHR-signaling and dietary iodine, supporting the need for personalized treatment strategies.

Activation of mitogen-activated protein kinase signaling and development of papillary thyroid carcinoma in thyroid-stimulating hormone receptor D633H knockin mice.

Nonautoimmune hyperthyroidism (NAH) is rare and occurs due to a constitutively activating thyroid stimulating hormone receptor (TSHR) mutation. In contrast to other thyroid nodules, no further evaluation for malignancy is recommended for hot thyroid nodules. In the first model for NAH in mice nearly all homozygous mice had developed papillary thyroid cancer by 12 months of age. To further evaluate these mice, whole exome sequencing and phosphoproteome analysis were employed in a further generation of mice to identify any other mutations potentially responsible and to identify the pathways involved in thyroid carcinoma development. Only three genes (Nrg1, Rrs1, Rasal2) were mutated in all mice examined, none of which were known primary drivers of papillary thyroid cancer development. Wild-type and homozygous TSHR D633H knockin mice showed distinct phosphoproteome profiles with an enrichment of altered phosphosites found in ERK/mitogen-activated protein kinase (MAPK) signaling. Most importantly, phosphosites with known downstream effects included BRAF p.S766, which forms an inhibitory site: a decrease of phosphorylation at this site suggests an increase in MEK/ERK pathway activation. The decreased phosphorylation at BRAF p.S766 would suggest decreased AMP-activated protein kinase (AMPK) signaling, which is supported by the decreased phosphorylation of STIM1 p.S257, a downstream AMPK target. The modified phosphoproteome profile of the homozygous mice in combination with human literature suggests a potential signaling pathway from constitutive TSHR signaling and cAMP activation to the activation of ERK/MAPK signaling. This is the first time that a specific mechanism has been identified for a possible involvement of TSH signaling in thyroid carcinoma development.

Letter to the Editor: Successful Prenatal Management of Inherited Congenital Non-Autoimmune Hyperthyroidism.

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High IGG4 serum levels in graves' disease compared with nonautoimmune hyperthyroidism

High IGG4 serum levels in graves' disease compared with nonautoimmune hyperthyroidism

Anti-nuclear autoantibodies in Graves’ disease and Graves’ orbitopathy

ObjectiveA relationship between thyroid and non-organ-specific autoimmunity could be relevant for Graves’ orbitopathy (GO), which affects connective tissue. We investigated the association between GO and anti-nuclear antibodies (ANAs).MethodsRetrospective investigation was conducted in 265 patients with Graves’ disease (GD), 158 with and 107 without GO. Primary outcome was: prevalence of ANAs in GO vs no-GO. Secondary outcomes were: (1) relationship between ANAs and GO features; (2) prevalence of ANAs in GD compared with non-autoimmune hyperthyroidism [(78 patients with toxic nodular goiter (TNG)]; (3) distribution of ANA patterns.ResultsANAs were detected in 212 (80%) GD patients, but prevalence did not differ between GO (79.7%) and no-GO (80.3%). Higher ANA titers (1:160) were more common in GO (51.5 vs 38.3%), but only nearly significantly (OR 0.5; 95% CI: 0.3–1; P = 0.059). Proptosis was lower in ANA-positive patients (mean difference: − 1.4 mm; 95% CI from − 2.5 to − 0.3; P = 0.011), in whom nearly significantly lower CAS (Mann–Whitney U: 1.5; P = 0.077) and eyelid aperture (mean difference: − 0.9 mm; 95% CI from − 2 to 0; P = 0.062) were observed. Prevalence of ANAs in GD was lower than in TNG (80 vs 91%; OR 0.3; 95% CI: 0.1–0.9; P = 0.028), but nuclear speckled pattern was more frequent (OR 22.9; 95% CI 1.3–381.3; P = 0.028).ConclusionsAlthough ANAs are not more frequent in GO, they seem to exert a protective role on its severity and on development of GD. A switch of T cell population in ANA-positive patients, resulting in a different phenotype, may be responsible. Further studies are needed to investigate the mechanisms.

Thyrotropin receptor antagonists and inverse agonists, and their potential application to thyroid diseases.

The thyrotropin receptor (TSHR) plays critical roles in thyroid growth and function and in the pathogenesis of several thyroid diseases including Graves' hyperthyroidism and ophthalmopathy, non-autoimmune hyperthyroidism and thyroid cancer. Several low-molecular weight compounds (LMWCs) and anti-TSHR monoclonal antibodies (mAbs) with receptor antagonistic and inverse agonistic activities have been reported. The former binds to the pocket formed by the receptor transmembrane bundle, and the latter to the extracellular TSH binding site. Both are effective inhibitors of TSH/thyroid stimulating antibody-stimulated cAMP and/or hyaluronic acid production in TSHR-expressing cells. Anti-insulin-like growth factor 1 inhibitors are also found to inhibit TSHR signaling. Each agent has advantages and disadvantages; for example, mAbs have a higher affinity and longer half-life but are more costly than LMWCs. At present, mAbs appear most promising, yet the development of more efficacious LMWCs is desirable. These agents are anticipated to be efficacious not only for the above-mentioned diseases but also for resistance to thyroid hormone and have utility for thyroid cancer radionuclide scintigraphy/therapy as a new theranostic.

Report of a family with three generations of undiagnosed familial nonautoimmune hyperthyroidism.

SummaryFamilial nonautoimmune hyperthyroidism (FNAH) is rare and occurs due to a constitutively activating thyroid-stimulating hormone receptor (TSHR) germline mutation. Forty-one families with FNAH have been reported so far. In the study, 17 of 41 families were not diagnosed with FNAH until three generations or more were described with hyperthyroidism. We report a case of FNAH diagnosed in the third generation. The index patient was diagnosed with hyperthyroidism at age 3. Large fluctuations in thyroid hormone levels occurred during anti-thyroid drug treatment, and he developed a goiter. The patient’s mother had similar history, requiring two surgical interventions and radioiodine treatment. The younger brother of the index patient did not experience large thyroid hormone level fluctuations, nor increased thyroid growth. A heterozygous TSHR c.1357A>G mutation, resulting in a M453V amino acid exchange, was detected in all three patients leading to FNAH diagnosis, with complete genotype–phenotype segregation. Based on Sorting intolerant from tolerant (SIFT) and PolyPhen2 scores of 0.01 and 0.99, respectively, an effect on protein function can be assumed. As illustrated by this family with FNAH, total thyr oidectomy is necessary for patients with nonautoimmune hyperthyroidism. Development of goiter is common, anti-thyroid drug treatment is often difficult, and remission of hyperthyroidism does not occur after discontinuation of anti-thyroid drug treatment. Thus, early diagnosis and appropriate treatment of FNAH is necessary to avoid predictable, unnecessary complications and further surgical interventions.Learning pointsIn the study, 19/42 cases of familial nonautoimmune hyperthyroidism (FNAH), including the reported case, were not diagnosed as FNAH until the third generation; this lead to suboptimal treatment and frequent relapses of nonautoimmune hyperthyroidism (NAH).Detection of thyroid-stimulating hormone receptor (TSHR) mutations in patients with suspected FNAH to confirm diagnosis is essential to ensure proper treatment for the patient and further affected family members.NAH will persist without proper treatment by total thyroidectomy.Symptoms and age of onset may vary between family membersAll family members with a TSHR germline mutation should be monitored with thyroid-stimulating hormone and for symptoms throughout their lives.

A Case of Definitive Therapy in Persistent Congenital Hyperthyroidism Secondary to an Activating Variant of the TSHR Gene

Background: Sporadic congenital non-autoimmune hyperthyroidism (SCNAH) causes permanent hyperthyroidism secondary to activating mutations in the TSHR gene. SCNAH usually presents during infancy and can be difficult to treat with antithyroid drugs or subtotal thyroidectomy.1 When adequate therapy is delayed, irreversible sequela such as craniosynostosis, growth failure, and cognitive delays may develop. Definitive therapy for children with SCNAH is recommended with no consensus on timing or type of intervention. Our case highlights the importance of early total thyroidectomy to optimize clinical outcomes in patients with SCNAH.Clinical case: A now 3-year-old male was born small for gestational age (SGA) at 34 weeks gestation with biochemical and clinical signs of hyperthyroidism in the neonatal period. On day of life 6, his TSH was 0.02 mcU/mL (reference range 0.34-5.6 mcU/mL) and free thyroxine (T4) was 5.42 ng/dL (reference range 0.58-1.64 ng/dL). Methimazole (MMI) 0.3 mg/kg/day was started at that time, and the dose was titrated over 6 weeks of life to 0.8 mg/kg/day due to continued elevation of free T4 levels. Negative thyroid autoantibodies and normal maternal thyroid studies prompted genetic testing at 3 months of age. This testing revealed a heterozygous variant in the TSHR gene [c.842G->A (p.G116R)] that was determined to be pathologic. Despite frequent MMI dose changes and confirmation of medication adherence, high-dose MMI was not effective in consistently normalizing his TSH and free T4 levels in the first two years of life. Concerns for poor growth and hyperactive behavior were also present. A “block and replace” strategy was not feasible since the patient remained hyperthyroid even at MMI doses up to 0.8 mg/kg/day. Despite normal insulin-like growth factor 1 and insulin-like growth factor binding protein 3 levels, poor linear growth persisted with a height Z-score of -3.61 by age 3 years. While he was SGA at birth, his recurrent hyperthyroidism impeded catch-up growth potential, so treatment with growth hormone (rhGH) was initiated. His height Z-score improved to -2.39 after 9 months on rhGH dosed at 0.18 mg/kg/week. Due to the difficulty in consistently managing him medically with MMI, he underwent total thyroidectomy at age three.Conclusion: There is currently no consensus on the timing of definitive therapy for children with SCNAH. This case highlights the importance of considering total thyroidectomy at an early age to avoid long-term sequela of persistent hyperthyroidism.1. Gozu HI, Lublinghoff J, Bircan R, Paschke R. Genetics and phenomics of inherited and sporadic non-autoimmune hyperthyroidism. Mol Cell Endocrinol. 2010;322:125–34.

Cytokines as Targets of Novel Therapies for Graves' Ophthalmopathy.

Graves’ disease (GD) is an organ-specific autoimmune disorder of the thyroid, which is characterized by circulating TSH-receptor (TSH-R) stimulating antibodies (TSAb), leading to hyperthyroidism. Graves’ ophthalmopathy (GO) is one of GD extra-thyroidal manifestations associated with the presence of TSAb, and insulin-like growth factor-1 receptor (IGF-1R) autoantibodies, that interact with orbital fibroblasts. Cytokines are elevated in autoimmune (i.e., IL-18, IL-6) and non-autoimmune hyperthyroidism (i.e., TNF-α, IL-8, IL-6), and this could be associated with the chronic effects of thyroid hormone increase. A prevalent Th1-immune response (not related to the hyperthyroidism per se, but to the autoimmune process) is reported in the immune-pathogenesis of GD and GO; Th1-chemokines (CXCL9, CXCL10, CXCL11) and the (C-X-C)R3 receptor are crucial in this process. In patients with active GO, corticosteroids, or intravenous immunoglobulins, decrease inflammation and orbital congestion, and are considered first-line therapies. The more deepened understanding of GO pathophysiology has led to different immune-modulant treatments. Cytokines, TSH-R, and IGF-1R (on the surface of B and T lymphocytes, and fibroblasts), and chemokines implicated in the autoimmune process, are possible targets of novel therapies. Drugs that target cytokines (etanercept, tocilizumab, infliximab, adalimumab) have been tested in GO, with encouraging results. The chimeric monoclonal antibody directed against CD20, RTX, reduces B lymphocytes, cytokines and the released autoantibodies. A multicenter, randomized, placebo-controlled, double-masked trial has investigated the human monoclonal blocking antibody directed against IGF-1R, teprotumumab, reporting its effectiveness in GO. In conclusion, large, controlled and randomized studies are needed to evaluate new possible targeted therapies for GO.

Familial Non-autoimmune Hyperthyroidism in Family Members Across Four Generations Due To a Novel Disease-causing Variant in The Thyrotropin Receptor Gene.

Activating disease-causing variants in the thyrotropin-receptor (TSHR) gene are associated with familial or sporadic congenital non-autoimmune hyperthyroidism. Familial non-autoimmune hyperthyroidism (FNAH) is a rare form of hyperthyroidism with 41 families reported so far in the TSHR gene mutation database. We present clinical and genetic features of 11 patients with FNAH across four generations of a Slovenian family. They all developed clinical features of hyperthyroidism but did not show characteristics of autoimmune hyperthyroidism. Members of the initially diagnosed generation were diagnosed as hyperthyrotic after they developed cardiac complications (rhythm disorders, thromboembolic events, cardiac insufficiency), while patients in the younger generations were diagnosed earlier, and consequently, early cardiovascular complications were less frequent. All patients had a novel heterozygous TSHR variant NP_ 000360.2: p.Met453Val (NM_000369.2: c.1357A>G) predicted to be pathogenic. Therefore, besides expending the mutational spectrum of the activating TSHR variants in FNAH, our experience with this multi-generation family confirms the need for early diagnosis and appropriate treatment of FNAH.

Prevalence and course of thyroid dysfunction in neonates at high risk of Graves' disease or with non-autoimmune hyperthyroidism.

Neonatal hyperthyroidism may be caused by a permanent non-autoimmune genetic disorder or, more frequently, by maternally transmitted high serum TRAb levels. Variable thyroid dysfunction may be observed in this second context. We aimed to evaluate the prevalence of neonatal non-autoimmune hyperthyroidism and of the different types of thyroid function in neonates with a high risk of hyperthyroidism due to maternal Graves' disease (GD). This observational cohort study included all neonates identified in the database of a single academic pediatric care center, over a period of 13 years, as having non-autoimmune hyperthyroidism or an autoimmune disorder with high TRAb levels (above 6 IU/L) transmitted by their mothers. Patients were classified as having neonatal hyperthyroidism, hypothyroidism, or euthyroidism with a permanent or transient disorder. Two of the 34 consecutive neonates selected (6%) had permanent non-autoimmune hyperthyroidism due to germline (n = 1) or somatic (n = 1) mutations of the TSH receptor gene. The patients with high serum TRAb levels at birth had transient hyperthyroidism (n = 23), hypothyroidism (primary n = 2, central n = 3) or persistent euthyroidism (n = 4). These original findings highlight the need for careful and appropriate monitoring of thyroid function in the long term, not only for the rare patients with non-autoimmune neonatal hyperthyroidism, but also for repeat monitoring during the first month of life in neonates with maternally transmitted high TRAb levels, to ensure the early identification of thyrotoxicosis in more than two thirds of cases and to detect primary or central hypothyroidism, thereby potentially decreasing associated morbidity.

SUN-476 Risk of Thyroid Cancer in McCune-Albright Syndrome

Background: McCune-Albright syndrome (MAS) is a well described genetic syndrome characterized by café-au-lait spots, polyostotic fibrous dysplasia, and hyperfunctioning endocrinopathies. Hyperthyroidism is a common endocrine manifestation of MAS, but thyroid nodules are less frequently observed. Thyroid cancer is generally considered uncommon in patients affected by MAS. Clinical Case: A 15-year-old male was referred to endocrinology for evaluation of polyostotic fibrous dysplasia with onset at 6 years old. He had no café-au-lait spots and initial labwork revealed no endocrine abnormalities. Subsequent labwork revealed non-autoimmune hyperthyroidism, leading to a diagnosis of MAS. Repeat clinical assessment revealed a goiter. 123-I uptake and scan revealed diffusely increased uptake throughout the gland with increased intensity in two regions of the right lobe separated by a region of photopenia. Ultrasound demonstrated three right-sided thyroid nodules – two correlating with the areas of increased iodine uptake and one with the area of photopenia. The left lobe of the thyroid was normal. FNA biopsy was performed and cytopathology was consistent with Bethesda II and III for the hyperfunctioning nodules and Bethesda VI for the cold nodule.The patient received total thyroidectomy with right-sided central neck dissection, and he was found to have multiple foci of papillary thyroid carcinoma with central neck metastases. The largest hyperfunctioning thyroid nodule was benign. He received radioactive iodine ablation which demonstrated no distant metastases and has had no evidence of recurrent disease. Conclusions: Hyperthyroidism is a common manifestation of MAS, but thyroid nodules are much less frequently observed, and thyroid cancer is considered quite rare. This patient developed TSH-independent hyperthyroidism in normal thyroid cells as well as in two hyperfunctioning thyroid nodules. He developed two contemporaneous classical papillary thyroid cancers – one manifesting as a nonfunctioning thyroid nodule and one manifesting as a thyrotoxic nodule with lymphatic invasion.We conclude that individuals with MAS may be at an increased risk for thyroid nodules and thyroid cancer, although the data are not well established. Clinicians should have a low threshold for thyroid ultrasound in patients with MAS and goiter. Reference: (1) Collins, M. T., Sarlis, N. J., Merino, M. J., Monroe, J., Crawford, S. E., Krakoff, J. A., Guthrie, L. C., Bonat, S., Robey, P. G., & Shenker, A. (2003). Thyroid carcinoma in the McCune-Albright syndrome: contributory role of activating Gsα mutations. The Journal of Clinical Endocrinology & Metabolism, 88(9), 4413-4417.(2) Hannon, T. S., Noonan, K., Steinmetz, R., Eugster, E. A., Levine, M. A., & Pescovitz, O. H. (2003). Is McCune-Albright syndrome overlooked in subjects with fibrous dysplasia of bone?. The Journal of pediatrics, 142(5), 532-538.

A Case of Familial Nonautoimmune Hyperthyroidism During Pregnancy

Familial nonautoimmune hyperthyroidism (FNAH) is a rare disease. To date there are few, if any, reports of pregnancies in women with FNAH. Our objective here is to present such a case. Free thyroxine (free T4), free triiodothyronine (free T3), thyroid-stimulating hormone (TSH), and antibodies related to the thyroid were measured. Fetal thyroid function indicators including thyroid volume and ossification were checked using ultrasound. Thyroid-stimulating hormone receptor (TSHR) gene analyses were performed. The patient was a 30-year-old woman with no past medical history. She was introduced to our hospital in the fifth gestational week for pregnancy care because her family history revealed that her mother had nonautoimmune hyperthyroidism with a TSHR-activating germ-line mutation (Asn406Ser). The serum free T4 was 1.88 ng/dL (normal, 0.62 to 1.19 ng/dL), free T3 was 3.27 pg/mL (normal, 2.55 to 3.88 pg/mL), TSH was 0.02 μIU/mL (normal, 0.007 to 3.619 μIU/mL), and TSHR was negative which were considered to be consistent with mild primary hyperthyroidism. Serum free T4, free T3, and TSH concentrations were monitored every 4 to 6 weeks with a peak free T4 of 2.23 ng/dL noted at gestational week 9. The patient had no signs related to hyperthyroidism throughout pregnancy. The patient delivered a 3,518 g girl at 40 weeks of gestation. Genetic analysis of her TSHR gene showed heterozygous Asn406Ser mutation. The offspring did not show any signs of prenatal hyperthyroidism, and thyroid function at day 6 after delivery revealed a free T4 of 2.41 ng/dL (normal, 1.83 to 2.91 ng/dL) and a TSH of 3.55 μIU/mL (normal, 0.51 to 4.57 μIU/mL). Women with FNAH and mild thyrotoxicosis prior to pregnancy may have continuous hyperthyroidism with additional change due to the series of human chorionic gonadotropin secretion during pregnancy.

Case Reports of Familial Non-autoimmune Hyperthyroidism in Two Malaysian Families due to Germline-activating Mutations in the Thyrotropin Receptor Gene

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The Role of HSP72 in Patient with Graves ‘disease and Non-autoimmune Hyperthyroidism in AL-Najaf Province

The Role of HSP72 in Patient with Graves ‘disease and Non-autoimmune Hyperthyroidism in AL-Najaf Province

MON-264 Familial Neonatal Nonautoimmune Hyperthyroidism Due To A Thyrotropin Receptor Gene Mutation (A619G).

Activating germline mutations of the TSH receptor are responsible for a rare form of non-autoimmune hyperthyroidism transmitted as an autosomal dominant trait. We describe the case of a patient and her mother presenting with neonatal non-autoimmune hyperthyroidism associated with a heterozygous A619G mutation previously described in one patient who presented in adolescence. Our patient is a 6 year old African-American female diagnosed with hyperthyroidism at 2 weeks of age. Thyroid tests were being followed in the NICU due to maternal history of hyperthyroidism. The mother had a history of hyperthyroidism and had thyroidectomy at age 4 years. The patient was thought to have neonatal Graves disease due to maternal history of hyperthyroidism. She was initially started on Propranolol at an outside hospital. She presented to the Children’s Hospital of Michigan Emergency Department at 7 weeks of age with tachycardia and constant crying. Her thyroid tests at that time revealed elevated free thyroxine and free T3 levels at 2.7 ng/mL (0.8-1.8) and 8.8 pg/mL (1.4- 4.4) respectively. TSH level was less than 0.008 µIU/mL (0.800-4.400). She had diffuse goiter. She was started on Methimazole and the dose was adjusted to keep her FT4 and T3 within normal range; TSH remained suppressed despite normalizing FT4 and T3 levels. Thyroid antibodies were repeatedly negative including Thyroid peroxidase, thyroid microsomal, thyroglobulin antibodies, thyrotropin receptor antibodies (TRab) and thyroid stimulating immunoglobulins (TSI). The patient also had bilateral exotropia and required strabismus surgery at 13 and at 17 months of age. She also has global developmental delay requiring physical, occupational, and speech therapy. Chromosomal microarray and fragile X DNA testing were normal. She is currently growing at 1.7 SDS for height and 0.8 SDS for weight and is on Methimazole 7.5 mg orally daily. TSHR sequencing and deletion/duplication analysis revealed that she is heterozygous for a missense variant: c.1856A>G; p.Asp619Gly. We report a case of a patient and her mother with non-autoimmune hyperthyroidism with a heterozygous c.1856A>G (p.Asp619Gly) missense variant in the TSHR gene. This variant has been previously identified in one individual in the compound heterozygous state and was considered to be the primary contributing mutation. Functional studies suggest that the variant leads to constitutive activity of the TSH receptor, supporting the pathogenicity of the variant. In our patient, the mutation was found to be inherited from the mother who also has a history of goiter and hyperthyroidism and unlike the previously reported case, our patient presented in the neonatal period. We describe the clinical course and associated findings in this family and discuss the evaluation and management of this interesting condition.

Hyperthyroidism and Papillary Thyroid Carcinoma in Thyrotropin Receptor D633H Mutant Mice.

Constitutively active thyrotropin receptor (TSHR) mutations are the most common etiology of non-autoimmune hyperthyroidism (NAH). Thus far, the functionality of these mutations has been tested in vitro, but the in vivo models are lacking. To understand the pathophysiology of NAH, the patient-derived constitutively active TSHR D633H mutation was introduced into the murine Tshr by homologous recombination. In this model, both subclinical and overt hyperthyroidism was observed, depending on the age, sex, and genotype. Homozygous mice presented hyperthyroidism at two months of age, while heterozygous animals showed only suppressed thyrotropin. Interestingly, at six months of age, thyroid hormone concentrations in all mutant mice were analogous to wild-type mice, and they showed colloid goiter with flattened thyrocytes. Strikingly, at one year of age, nearly all homozygous mice presented large papillary thyroid carcinomas. Mechanistically, this papillary thyroid carcinoma phenotype was associated with an overactive thyroid and strongly increased stainings of proliferation-, pERK-, and NKX2-1 markers, but no mutations in the "hot-spot" areas of common oncogenes (Braf, Nras, and Kras) were found. This is the first study to reveal the dynamic age-, sex-, and genotype-dependent development of NAH. Furthermore, the study shows that a constitutively active TSHR can trigger a malignant transformation of thyrocytes.

Advanced Bone Age Present in a Neonatal Case of Sporadic Non-Autoimmune Hyperthyroidism Before Onset of Symptoms

Advanced Bone Age Present in a Neonatal Case of Sporadic Non-Autoimmune Hyperthyroidism Before Onset of Symptoms

Long-Term Follow-Up of a Patient with Sporadic Nonautoimmune Hyperthyroidism Due to a Thyrotropin-Receptor Mutation (D619G)

ABSTRACT Objective: Sporadic nonautoimmune hyperthyroidism caused by germline mutations of the thyrotropin receptor (TSHR) gene is a very rare disease that manifests as severe congenital hyperthyroidism. We describe a case presenting with sporadic nonautoimmune hyperthyroidism during adolescence. Methods: Laboratory data, imaging, histopathology, clinical follow-up, and DNA sequencing were evaluated. Results: The patient was born at term with a normal birth weight but showed increased growth velocity at approximately 7 months. He had no medical consultation before tachycardia was detected at a school physical examination at the age of 13 years. Thyroid function tests confirmed hyperthyroidism with negative anti-TSHR antibodies. After maintaining methimazole therapy for 12 years, he underwent total thyroidectomy, and the weight of the resected thyroid tissue was 131 g. The subsequent histopathologic findings showed an encapsulated follicular adenoma, adenomatous goiter, and hyperplastic changes of the foll...

Novel germline mutation (Leu512Met) in the thyrotropin receptor gene (TSHR) leading to sporadic non-autoimmune hyperthyroidism.

Primary nonautoimmune hyperthyroidism is a rare cause of neonatal hyperthyroidism. This results from an activating mutation in the thyrotropin-receptor (TSHR). It can be inherited in an autosomal dominant manner or occur sporadically as a de novo mutation. Affected individuals display a wide phenotype from severe neonatal to mild subclinical hyperthyroidism. We describe a 6-month-old boy with a de novo mutation in the TSHR gene who presented with accelerated growth, enlarging head circumference, tremor and thyrotoxicosis. Genomic DNA from the patient's and parents' peripheral blood leukocytes was extracted. Exons 9 and 10 of the TSHR gene were amplified by PCR and sequenced. Sequencing exon 10 of the TSHR gene revealed a novel heterozygous missense mutation substituting cytosine to adenine at nucleotide position 1534 in the patient's peripheral blood leukocytes. This leads to a substitution of leucine to methionine at amino acid position 512. The mutation was absent in the parents. In silico modeling by PolyPhen-2 and SIFT predicted the mutation to be deleterious. The p.Leu512Met mutation (c.1534C>A) of the TSHR gene has not been previously described in germline or somatic mutations. This case presentation highlights the possibility of mild thyrotoxicosis in affected individuals and contributes to the understanding of sporadic non-autoimmune primary hyperthyroidism.