Single nucleotide polymorphism 1623 A/G (rs180195) in the promoter of the Thyroglobulin gene is associated with autoimmune thyroid disease but not with thyroid ophthalmopathy

Unraveling susceptibility genes: A contemporary overview of autoimmune thyroid diseases

Autoimmune thyroid diseases (AITDs), including Graves' disease and Hashimoto's thyroiditis, are organ-specific autoimmune disorders characterized by conditions including goiter, autoimmune thyroiditis, hyperthyroidism, and hypothyroidism, which represent the most severe clinical manifestations of AITDs. The prevalence of autoimmune thyroid disorders is on the rise, influenced by increased environmental factors and changes in modern lifestyles. Understanding the pathophysiology of AITDs is crucial for identifying key factors that affect the disease's onset, progression, and recurrence, thereby laying a solid foundation for precise diagnosis and treatment. The development of AITDs involves a complex interplay of environmental influences, immune dysfunctions, and genetic predispositions. Genetic predispositions, in particular, are significant, with numerous genes identified as being linked to AITDs. This article focuses on examining the genes vulnerable to AITDs to deepen our understanding of the relevant genetic contributors, ultimately facilitating the development of effective prevention and treatment methods.

Is There a Link between Thyroid Peroxidase Gene Promoter Polymorphisms and Autoimmune Thyroiditis in the Polish Population?

(1) Autoimmune thyroiditis (AIT) is the most common cause of primary hypothyroidism and one of the most frequent organ-specific autoimmune diseases. Its pathogenesis is polygenic and still requires further research. The aim of the study was to assess, for the first time in the Caucasian population, the role of selected TPO gene promoter polymorphisms (rs2071399 G/A, rs2071400C/T, rs2071402 A/G, and rs2071403 A/G) in the development of AIT. A total of 237 patients diagnosed with AIT and 130 healthy controls were genotyped for four TPO gene polymorphisms, and the results were statistically analyzed to check for the role of these polymorphisms. There were no significant differences in the genotype and allele frequencies of the studied TPO gene promoter polymorphisms between patients and controls (p > 0.05). The haplotype distribution (rs2071400-rs2071402-rs2071403) between the two studied groups was similar for the most common variants (CGA, CAG, TGG). Only a rare haplotype (CGG) occurred more frequently among patients compared to controls (p = 0.04). The studied TPO gene promoter polymorphisms did not show an association with susceptibility to AIT in the Caucasian Polish population, contrary to the results in Japanese patients.

Molecular Mechanisms in Autoimmune Thyroid Disease

The most common cause of acquired thyroid dysfunction is autoimmune thyroid disease, which is an organ-specific autoimmune disease with two presentation phenotypes: hyperthyroidism (Graves-Basedow disease) and hypothyroidism (Hashimoto’s thyroiditis). Hashimoto’s thyroiditis is distinguished by the presence of autoantibodies against thyroid peroxidase and thyroglobulin. Meanwhile, autoantibodies against the TSH receptor have been found in Graves-Basedow disease. Numerous susceptibility genes, as well as epigenetic and environmental factors, contribute to the pathogenesis of both diseases. This review summarizes the most common genetic, epigenetic, and environmental mechanisms involved in autoimmune thyroid disease.

Genetics and epigenetics of autoimmune thyroid diseases: Translational implications

Hashimoto's thyroiditis (HT) and Graves' disease (GD) are prevalent autoimmune disorders, representing opposite ends of the clinical spectrum of autoimmune thyroid diseases (AITD). The pathogenesis involves a complex interplay between environment and genes. Specific susceptibility genes have been discovered that predispose to AITD, including thyroid-specific and immune-regulatory genes. Growing evidence has revealed that genetic and epigenetic variants can alter autoantigen presentation during the development of immune tolerance, can enhance self-peptide binding to MHC (major histocompatibility complex), and can amplify stimulation of T- and B-cells. These gene-driven mechanistic discoveries lay the groundwork for novel treatment targets. This review summarizes recent advances in our understanding of key AITD susceptibility genes (Tg¹, TSHR, HLA-DR3, and CD40) and their translational therapeutic potential.

A case report of thyroid-associated Orbitopathy with elevated TPO antibodies

BACKGROUND

Thyroid associated orbitopathy (TAO) is defined as an immune mediated inflammatory process affecting the extraocular muscles, connective and adipose tissue of uncertain etiopathogenesis. TAO are classically described in Grave's disease (GD) however it may occur in euthyroid and hypothyroid patients. Those patients usually test positive for Thyroid Stimulating Hormone receptor antibodies (TRAb). For instance, only few cases of severe Hashimoto's thyroiditis (HT) associated orbitopathy with negative TRAb are reported to date.

CASE PRESENTATION

Herewith we report a rare case of a middle-aged female who presented with bilateral progressive upper and lower palpebral edema and a unilateral marked proptosis associated with asthenia, headache and decrease in visual acuity. Biological investigation was notable for high levels of anti-thyroid peroxidase antibodies (Anti-TPO) in an otherwise euthyroid patient with negative TRAb. Orbital Magnetic resonance imaging revealed edema of the extraocular muscles and inflammation of periorbital soft tissue. The patient received a treatment with intravenous methylprednisolone followed by oral treatment with prednisone. This regimen was both effective and safe with minimal metabolic side effects in our patient.

CONCLUSION

Minor ocular manifestations of HT are common; however, severe sight threatening ophtalmopathy in the absence of TRAb is rare. Multiple differential diagnosis should be considered and investigated before diagnosing this rare entity. Management of similar cases is currently based on reports and no clear guidelines have been elaborated, corticosteroids is the mainstream of treatment with a potential benefit of selenium supplementation in mild to moderate cases.

Severe unilateral orbitopathy in a patient with Hashimoto's thyroiditis - a case report

Background

Thyroid-associated orbitopathy (TAO) constitutes an immune-mediated inflammation of the orbital tissues of unclear etiopathogenesis. TAO is most prevalent in hyperthyroid patients with Graves’ disease (GD); however, severe cases of orbitopathy associated with Hashimoto’s thyroiditis (HT) have rarely been described.

Case presentation

Herewith we report an unusual case of a middle-aged clinically and biochemically euthyroid woman with a stable HT, who developed a severe unilateral left-sided TAO. Thyrotropin receptor antibodies (TRAb) concentration was negative. Intraocular pressure in the left eye was mildly elevated (24 mmHg), while vision acuity was not compromised. Abnormal positioning of the eyeball suggested the extraocular muscles involvement. Unilaterally, von Graefe’s, Stellwag’s, Kocher’s and Moebius' signs were positive. Conjunctival erythema, redness and edema of the eyelid and an enlarged, swollen lacrimal caruncle were visible. She received 4/7 points in the Clinical Activity Scale (CAS) and class IV in the NO SPECS severity scale for the left eye (I-0, II-a, III-0, IV-b, V-0, VI-0). Magnetic resonance imaging (MRI) revealed thickening of the left medial rectus muscle with an increase in T2 signal intensity and prolonged T2 relaxation indicating an active form of TAO. The patient received therapy with glucocorticosteroids intravenously, followed by intramuscular injections with a cumulative dose of 3.24 g of methylprednisolone during a 9-week period with good tolerance. The applied therapy, combined with adequate L-thyroxine substitution, as well as vitamin D and selenium supplementation, resulted in a complete remission of ophthalmic symptoms.

Conclusions

Unilateral exophthalmos in TRAb-negative patients with HT is not a typical manifestation of the disease, and requires a wider differential diagnosis with MRI of the orbits. Scheme of three iv. pulses of methylprednisolone intravenously and the continuation of treatment with im. injections seems to be an effective and safe method of treatment in this group of patients. What is more, adequate vitamin D supplementation and the maintenance of biochemical euthyroidism may help to achieve an ultimate therapeutic effect. Patients with TAO in the course of HT need a careful and continued interdisciplinary approach both ophthalmological and endocrinological. Further studies are needed to elucidate the etiopathogenesis of TAO in TRAb-negative patients.