The role of genetics in Graves' disease and thyroid orbitopathy

Thyroid-Associated Orbitopathy and Biomarkers: Where We Are and What We Can Hope for the Future

Background

Thyroid-associated orbitopathy (TAO) is the most common autoimmune disease of the orbit. It occurs more often in patients presenting with hyperthyroidism, characteristic of Graves' disease, but may be associated with hypothyroidism or euthyroidism. The diagnosis of TAO is based on clinical orbital features, radiological criteria, and the potential association with thyroid disease. To date, there is no specific marker of the orbital disease, making the early diagnosis difficult, especially if the orbital involvement precedes the thyroid dysfunction.

Summary

The goal of this review is to present the disease and combine the available data in the literature concerning investigation of TAO biomarkers.

Conclusions

Despite the progress done in the understanding of TAO disease, some important pieces are still missing. Typically, for the future, major efforts have to be done in the discovery of new biomarkers, validation of the suspected candidates on multicenter cohorts with standardized methodologies, and establishment of their clinical performances on the specific clinical application fields in order to improve not only the management of the TAO patients but also the therapeutic options and follow-up.

Disturbances of modulating molecules (FOXP3, CTLA-4/CD28/B7, and CD40/CD40L) mRNA expressions in the orbital tissue from patients with severe graves' ophthalmopathy

Purpose. To evaluate the relationship between the expression of orbital tissue mRNA for FOXP3, CTLA-4/CD28/CD80/CD86, and CD40/CD40 and the severity of Graves' orbitopathy (GO). Material and Methods. Orbital tissue was obtained from 26 patients with GO, with mild (n = 6) or severe GO (n = 20), and 7 healthy controls. The expression of mRNA of FOXP3, CTLA-4/CD28/CD80/CD86, CD40/CD40L was measured by RT-PCR. TCR and CD3 were evaluated by immunohistochemistry. Results. Higher mRNA for FoxP3 (relative expression: 1.4) and CD40 (1.27) and lower expression of CTLA-4 (0.61) were found in the GO tissues versus controls. In severe GO as compared to mild GO higher mRNA expression for FoxP3 (1.35) and CD40 (1.4) and lower expression for CTLA-4 (0.78), CD28 (0.62), and CD40L (0.56) were found. A positive correlation was found between FOXP3 mRNA and CD3 infiltration (R = 0.796, P = 0.0000001). Conclusions. The enhanced FOXP3 mRNA expression in GO samples may suggest the dysfunction of FOXP3 cells in the severe GO. The diminished mRNA expression of CTLA-4 in severe GO may indicate inadequate T regulatory function. The enhanced mRNA expression of CD40 in severe GO and negative correlation to CRP mRNA may suggest their role in the active and inactive GO.

Association between polymorphisms in the TSHR gene and Graves' orbitopathy

BACKGROUND

Graves' orbitopathy (GO) as well as Graves' disease (GD) hyperthyroidism originate from an autoimmune reaction against the common auto-antigen, thyroid-stimulating hormone receptor (TSHR). GO phenotype is associated with environmental risk factors, mainly nicotinism, as well as genetic risk factors which initiate an immunologic reaction. In some patients GO is observed before diagnosis of GD hyperthyroidism, while it can also be observed far after diagnosis. The intensity of GO symptoms varies greatly in these patients. Thus, the pathogenesis of GD and GO may correlate with different genetic backgrounds, which has been confirmed by studies of correlations between GO and polymorphisms in cytokines involved in orbit inflammation. The aim of our analysis was to assess genetic predisposition to GO in young patients (age of diagnosis ≤30 years of age), for whom environmental effects had less time to influence outcomes than in adults.

METHODS

768 GD patients were included in the study. 359 of them had clinically evident orbitopathy (NOSPECS ≥2). Patients were stratified by age at diagnosis. Association analyses were performed for genes with a known influence on development of GD - TSHR, HLA-DRB1, cytotoxic T-lymphocyte antigen 4 (CTLA4) and lymphoid protein tyrosine phosphatase (PTPN22).

RESULTS

The rs179247 TSHR polymorphism was associated with GO in young patients only. In young GO-free patients, allele A was statistically more frequent and homozygous carriers had a considerable lower risk of disease incidence than patients with AG or GG genotypes. Those differences were not found in either elderly patients or the group analyzed as a whole.

CONCLUSIONS

Allele A of the rs179247 polymorphism in the TSHR gene is associated with lower risk of GO in young GD patients.

Graves' ophthalmopathy: a review of immunogenetics

Graves’ disease (GD) is the most common cause of thyrotoxicosis and often involves the orbits. Graves’ ophthalmopathy (GO), also known as Thyroid Eye Disease (TED), can be clinically significant and advance to sight-threatening stages. Our knowledge of the immunogenetic pathophysiology of GO is rapidly expanding. The present review is an attempt to summarize the current state of knowledge on the immunogenetics of GO. First we briefly review the epidemiology and clinical importance of GO, and then we describe in detail the macromolecular pathogenesis and finally immunogenetics of GO. Discrepancies between the results from various reports and the limitations of the available data are discussed. In particular, there is a scarcity of data from non-Asian populations. While several studies have demonstrated significant associations between polymorphisms in certain genes (especially CTLA-4, HLA-DRB-1, and TNF-α), there is a need for studies that investigate the relationship between polymorphisms and both serum and local concentrations of the resulting proteins. A complete understanding of GO susceptibility and pathogenesis has not been yet possible due to a number of important knowledge gaps that need to be filled by future research.

Eye findings and immunological markers in probands and their euthyroid relatives from a single family with multiple cases of thyroid autoimmunity

Background

Ophthalmopathy is a common manifestation of Graves’ disease (GD) occurring in up to 50% of patients. Mild eye signs are also common in patients with Hashimoto’s thyroiditis. Whilst a genetic predisposition to GD has been demonstrated this is not the case for the ophthalmopathy which often runs a separate course.

Objective

We determined the prevalences of eye and eyelid signs and positive thyroid and orbital antibody tests in first and second degree relatives from a single family with multiple cases of Graves’ disease, ophthalmopathy and Hashimoto’s thyroiditis.

Design

The study cohort comprised 16 subjects from the same family, 4 probands namely, 3 with GD and one with Hashimoto’s thyroiditis and hypothyroidism and 12 of their euthyroid first or second degree relatives. We measured antibodies against calsequestrin (CASQ1) and collagen XIII in an enzyme-linked-immunosorbent assays and TSH-Receptor (TSH-R) antibodies as i) TSH-R binding inhibiting immunoglobulin (TBII) and ii) thyroid stimulating immunoglobulin (TSI). Eye signs were classified and quantified using the clinical activity score (CAS), NOSPECS classes, Nunery types 1 and 2 and the margin-reflex-distance (MRD) as a measure of upper eyelid retraction (UER).

Main outcomes

Whilst significant ophthalmopathy was uncommon in the relatives, mild eye signs, in particular UER, were demonstrated in about a third of them. The presence of eye signs was moderately, but not significantly, associated with the detection of CASQ1 and collagen XIII antibodies, but not TSH-R antibodies.

Conclusion

Our study demonstrates a significant prevalence of positive orbital antibody tests and ophthalmopathy in probands with thyroid autoimmunity and their euthyroid relatives, favouring a role of genetic factors in the development of ophthalmopathy in patients with thyroid autoimmunity.

Thyroid eye disease: honing your skills to improve outcomes

Thyroid eye disease affects the eyelids, orbital compartment, and extraocular muscles, resulting in a highly variable degree of chemosis and enlargement of the preorbital fat pads, eyelid retraction, proptosis, restrictive strabismus, torticollis, and, rarely, compressive or congestive optic neuropathy. Although most patients with thyroid eye disease are best treated conservatively, those more severely affected may benefit from orbital decompression, strabismus surgery, or eyelid retraction repair after stabilization has occurred. Botulinum A toxin, high-dose intravenous corticosteroids, and radiation treatment are therapeutic options in select cases. Compressive or congestive optic neuropathy and severe corneal exposure warrant consideration of surgical intervention on an urgent basis without waiting for stabilization. Epidemiology and risks and benefits of high-dose steroids and radiation therapy are reviewed along with recommendations to improve conservative as well as surgical management of this disease. Strategies to manage strabismus and optimize outcomes are provided.

Ophthalmic manifestations of endocrine disorders: approaches and medical management

PURPOSE OF REVIEW

Disorders of the endocrine system may present with various ophthalmic signs, symptoms, and pathology. Early detection, prevention, and monitoring of these manifestations can significantly benefit morbidity associated with such disease states including permanent visual dysfunction.

RECENT FINDINGS

Several studies highlight the importance of early diagnosis in reducing the long-term complications associated with these endocrine conditions, although these observations are mostly based on case reports and case series.

SUMMARY

This review will focus on the connection of endocrine-related disease states with the development of specific ophthalmic pathology and is geared towards the general medical practitioner. The focus of the treating physician should be on facilitating early diagnosis to prevent potentially blinding complications.

Autoimmune disease in a DFNA6/14/38 family carrying a novel missense mutation in WFS1

Most familial cases of autosomal dominant low frequency sensorineural hearing loss (LFSNHL) are attributable to mutations in the wolframin syndrome 1 (WFS1) gene at the DFNA6/14/38 locus. WFS1 mutations at this locus were first described in 2001 in six families segregating LFSNHL that was non-progressive below 2,000 Hz; the causative mutations all clustered in the C-terminal domain of the wolframin protein. Mutations in WFS1 also cause Wolfram syndrome (WS), an autosomal recessive neurodegenerative disorder defined by diabetes mellitus, optic atrophy and often deafness, while numerous single nucleotide polymorphisms (SNPs) in WFS1 have been associated with increased risk for diabetes mellitus, psychiatric illnesses and Parkinson disease. This study was conducted in an American family segregating autosomal dominant LFSNHL. Two hearing impaired family members also had autoimmune diseases-Graves disease (GD) and Crohn disease (CD). Based on the low frequency audioprofile, mutation screening of WFS1 was completed and a novel missense mutation (c.2576G --> A) that results in an arginine-to-glutamine substitution (p.R859Q) was identified in the C-terminal domain of the wolframin protein where most LFSNHL-causing mutations cluster. The family member with GD also carried polymorphisms in WFS1 that have been associated with other autoimmune diseases.