Sibling recurrence risk in autoimmune thyroid disease

Determinants for Thyroid Hormone Replacement Therapy in Subclinical Hypothyroidism: A Multicenter Electronic Health Records-Based Study

Background: The frequency and factors associated with thyroid hormone replacement therapy among patients with subclinical hypothyroidism (SCH) remain uncertain. Methods: In this electronic health records-based observational cohort study, we included adults diagnosed with SCH from four academic centers (the United States and Mexico) from January 1, 2016, to December 31, 2018. We aimed to identify the determinants of thyroid hormone replacement therapy for SCH and the frequency of treated SCH. Results: A total of 796 patients (65.2% women) had SCH, and 165 (20.7%) were treated with thyroid hormone replacement therapy. The treated group was younger [51.0 (standard deviation {SD} 18.3) vs. 55.3 (SD 18.2) years, p = 0.008] and had a higher proportion of women (72.7% vs. 63.2%, p = 0.03) compared with the untreated group. Only 46.7% of patients in the treated group and 65.6% in the untreated group had confirmatory thyroid function tests (TFTs) before the decision to start thyroid hormone replacement therapy was made. There was no difference in the frequency of thyroid autoimmunity evaluation, but a positive thyroid autoimmunity test was more frequent in the treated group compared with the untreated group (48.2% vs. 20.3%, p < 0.001). In a multivariable logistic regression model, female sex (odds ratio [OR] = 1.71 [CI 1.13-2.59], p = 0.01) and index thyrotropin (TSH) level (OR = 1.97 [CI 1.56-2.49], p < 0.001 for every SD [2.75 mIU/L] change) were associated with higher odds of treatment. Conclusions: Among patients with SCH, female sex and index TSH level were associated with higher odds of treatment. Moreover, in our population, the decision to treat or not to treat SCH was often based on only one set of abnormal TFTs, and thyroid autoimmunity assessment was underused.

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.

Recurrence risk of autoimmune thyroid and endocrine diseases

BACKGROUND AND OBJECTIVE

The recurrence risk ratio (λ) expresses the risk ratio of index patients' first-degree relatives developing a disease as compared to the general population and is a quantitative measure of the genetic contribution to the disease. This paper offers the results of a specialized center as well as a review of the pertinent literature.

METHODS

Data from 3315 consecutive subjects followed at an ORPHAN academic tertiary referral expert center for endocrine autoimmunity as well as 419 unrelated German families were collected. λ was assessed based on 806 well-documented subjects, 299 index patients with autoimmune glandular (AIGD) and non-endocrine diseases and 507 of their first-degree relatives (328 children, 179 siblings).

RESULTS

As many as 36% of relatives of patients with autoimmune diseases (AID) were affected by various autoimmune conditions. Twenty-five percent and 23% of all relatives had an AIGD or an autoimmune thyroid disease (AITD), respectively. Furthermore, 29% and 25% of relatives of index cases with polyglandular (PGA) and monoglandular (MGA) autoimmunity were affected. The recurrence risk for AITD was increased 16-fold in both children and siblings compared to the general population (λ, 95% CI 16, 11-21 and 16, 12-19, respectively). Furthermore, λ for AITD/AIGD was 21.62 (95% CI 14.17-30.69)/17.57 (11.80-24.36) and 13.48 (8.42-20.52)/10.68 (6.76-16.02) for siblings of patients with PGA and MGA, respectively. Overall, a strong genetic component for AITD and AIGD with a significant genetic impact on the development of PGA was demonstrated.

CONCLUSION

These novel results strongly recommend the screening for AITD and AIGD in children and siblings of index patients with AITD.

Familial Risk of Graves' Disease among First-Degree Relatives and Interaction with Smoking: A Population-Based Study

OBJECTIVE

Population-based studies on the familial aggregation of Graves' disease (GD) are scarce and gene-environment interactions are not well-studied. We evaluated the familial aggregation of GD and assessed interactions between family history and smoking.

METHODS

Using the National Health Insurance database, which includes information on familial relationships and lifestyle risk factors, we identified 5,524,403 individuals with first-degree relatives (FDRs). Familial risk was calculated using hazard ratios (HRs), which compare the risk of individuals with and without affected FDRs. Interactions between smoking and family history were assessed on an additive scale using relative excess risk due to interaction (RERI).

RESULTS

The HR among individuals with affected FDRs was 3.39 (95% CI 3.30-3.48) compared to those without affected FDR, and among individuals with affected twin, brother, sister, father and mother the HRs were 36.53 (23.85-53.54), 5.26 (4.89-5.66), 4.12 (3.88-4.38), 3.34 (3.16-3.54), and 2.63 (2.53-2.74), respectively. Individuals with both a positive family history and smoking had an increased risk of disease (HR 4.68) with statistically significant interaction (RERI 0.94 95% CI 0.74-1.19). Heavy smokers with a positive family history showed a nearly 6-fold increased risk, which was higher than moderate smoking, suggesting a dose-response interaction pattern. Current smoking also showed a statistically significant interaction with family history (RERI 0.52 95% CI 0.22-0.82), while this was not observed for former smoking.

CONCLUSION

A gene-environment interaction can be suggested between smoking and GD-associated genetic factors, which diminishes after smoking cessation. Smokers with a positive family history should be considered a high-risk group and smoking cessation should be advised.

Graves' disease and inflammatory bowel disease: A bidirectional Mendelian randomization

CONTEXT

Both Graves' disease (GD) and inflammatory bowel disease (IBD) are common autoimmune diseases that severely damage patients' quality of life. Previous epidemiological studies have suggested associations between GD and IBD. However, whether a causal relationship exists between these two diseases remains unknown.

OBJECTIVE

To infer a causal relationship between GD and IBD using bidirectional two-sample Mendelian randomization(MR).

METHODS

We performed bidirectional two-sample MR to infer a causal relationship between GD and IBD using GWAS summary data obtained from Biobank Japan (BBJ) and the International Inflammatory Bowel Disease Genetic Consortium (IIBDGC). Several methods (random-effect inverse variance weighted, weighted median, MR‒Egger regression, and MR-PRESSO) were used to ensure the robustness of the causal effect. Heterogeneity was measured based on Cochran's Q value. Horizontal pleiotropy was evaluated by MR‒Egger regression and leave-one-out analysis.

RESULTS

Genetically predicted IBD may increase the risk of GD by 24% (OR 1.24, 95% CI 1.01-1.52, p = 0.041). Crohn's disease (CD) may increase the risk of GD, whereas ulcerative colitis (UC) may prevent patients from developing GD. Conversely, genetically predicted GD may slightly increase the risk of CD, although evidence indicating that the presence of GD increased the risk of UC or IBD was lacking. Outlier-corrected results were consistent with raw causal estimates.

CONCLUSIONS

Our study revealed a potentially higher comorbidity rate for GD and CD. However, UC might represent a protective factor for GD. The underlying mechanism and potential common pathways await discovery.

Current concepts regarding Graves' orbitopathy

Graves' orbitopathy (GO) is an orbital autoimmune disorder and the main extrathyroidal manifestation of Graves' disease, the most common cause of hyperthyroidism. GO affects about 30% of Graves' patients, although fewer than 10% have severe forms requiring immunosuppressive treatments. Management of GO requires a multidisciplinary approach. Medical therapies for active moderate-to-severe forms of GO (traditionally, high-dose glucocorticoids) often provide unsatisfactory results, and subsequently surgeries are often needed to cure residual manifestations. The aim of this review is to provide an updated overview of current concepts regarding the epidemiology, pathogenesis, assessment, and treatment of GO, and to present emerging targeted therapies and therapeutic perspectives. Original articles, clinical trials, systematic reviews, and meta-analyses from 1980 to 2021 were searched using the following terms: Graves' disease, Graves' orbitopathy, thyroid eye disease, glucocorticoids, orbital radiotherapy, rituximab, cyclosporine, azathioprine, teprotumumab, TSH-receptor antibody, smoking, hyperthyroidism, hypothyroidism, thyroidectomy, radioactive iodine, and antithyroid drugs. Recent studies suggest a secular trend toward a milder phenotype of GO. Standardized assessment at a thyroid eye clinic allows for a better general management plan. Treatment of active moderate-to-severe forms of GO still relies in most cases on high-dose systemic-mainly intravenous-glucocorticoids as monotherapy or in combination with other therapies-such as mycophenolate, cyclosporine, azathioprine, or orbital radiotherapy-but novel biological agents-including teprotumumab, rituximab, and tocilizumab-have achieved encouraging results.

Effect of different iodine levels on the DNA methylation of PRKAA2, ITGA6, THEM4 and PRL genes in PI3K-AKT signaling pathway and population-based validation from autoimmune thyroiditis patients

PURPOSE

Autoimmune thyroiditis (AIT) is one of the most common autoimmune endocrine diseases. The currently recognized causes are genetic susceptibility, environmental factors and immune disorders. It is important to clarify the pathogenesis for the prevention, diagnosis, treatment of AIT and scientific iodine supplementation. This study analyzed the DNA methylation levels of PRKAA2, ITGA6, PRL and THEM4 genes related to PI3K-AKT signaling pathway, compared the DNA methylation levels between cases and controls from different water iodine levels in Shandong Province of China, and evaluated the contribution of PI3K-AKT signaling pathway-related genes in AIT.

METHODS

A total of 176 adult AIT patients were included from three different water iodine areas, and 176 healthy controls were included according to gender, age and BMI. According to the results of the Illumina Methylation 850 K BeadChip in our previous research, the significant methylation differences of genes on the PI3K-AKT signaling pathway related to AIT were determined. The MethylTarget™ assay was used to detect the methylation levels of the target genes, and real-time PCR experiments were used to verify the mRNA expression levels.

RESULTS

Compared with the control group, PRKAA2_3 and 15 CpG sites were hyper-methylated. ITGA6 gene and 2 CpG sites were hypo-methylated in AIT cases. The mRNA expression of ITGA6 gene was negatively correlated with the DNA methylation levels of ITGA6 gene and 2 CpG sites. Compared with cases and controls in areas with different water iodine levels, methylation differences were mainly in PRKAA2 and ITGA6 genes. The methylation levels of PRKAA2_1 and PRKAA2_3 were positively correlated with age. The methylation levels of PRL and THEM4 genes were negatively correlated with age. The methylation level of PRKAA2_3 was positively correlated with FT₄.

CONCLUSION

In summary, we identified aberrant DNA methylation levels of PRKAA2 and ITGA6 genes related to PI3K-AKT signaling pathway in the blood of AIT patients. Both iodine supplementation after long-term iodine deficiency and iodine excess can affect the DNA methylation levels of PRKAA2 and ITGA6 genes, and the former affects more obviously. In ITGA6 gene, this aberrant epigenetic modification is associated with the increased mRNA expression.

The Potential Prebiotic Berberine Combined With Methimazole Improved the Therapeutic Effect of Graves' Disease Patients Through Regulating the Intestinal Microbiome

Graves’ disease, a typical metabolism disorder, causes diffuse goiter accompanied by ocular abnormalities and ocular dysfunction. Although methimazole (MI) is a commonly used drug for the treatment of GD, the efficacy of methimazole is only limited to the control of clinical indicators, and the side effects of MI should be seriously considered. Here, we designed a 6-month clinical trial that divided the patients into two groups: a methimazole group (n=8) and a methimazole combined with potential prebiotic berberine group (n=10). The effects of both treatments on thyroid function and treatment outcomes in patients with GD were assessed by thyroid index measurements and gut microbiota metagenomic sequencing. The results showed that the addition of berberine restored the patients’ TSH and FT3 indices to normal levels, whereas MI alone restored only FT3. In addition, TRAb was closer to the healthy threshold at the end of treatment with the drug combination. MI alone failed to modulate the gut microbiota of the patients. However, the combination of berberine with methimazole significantly altered the microbiota structure of the patients, increasing the abundance of the beneficial bacteria Lactococcus lactis while decreasing the abundance of the pathogenic bacteria Enterobacter hormaechei and Chryseobacterium indologenes. Furthermore, further mechanistic exploration showed that the addition of berberine resulted in a significant upregulation of the synthesis of enterobactin, which may have increased iron functioning and thus restored thyroid function. In conclusion, methimazole combined with berberine has better efficacy in patients with GD, suggesting the potential benefit of berberine combined with methimazole in modulating the composition of intestinal microbes in the treatment of GD, providing new strong evidence for the effectiveness of combining Chinese and Western drugs from the perspective of modulating the intestinal microbiota.

2021 update on thyroid-associated ophthalmopathy

PURPOSE

Our understanding of thyroid-associated ophthalmopathy (TAO, A.K.A Graves' orbitopathy, thyroid eye disease) has advanced substantially, since one of us (TJS) wrote the 2010 update on TAO, appearing in this journal.

METHODS

PubMed was searched for relevant articles.

RESULTS

Recent insights have resulted from important studies conducted by many different laboratory groups around the World. A clearer understanding of autoimmune diseases in general and TAO specifically emerged from the use of improved research methodologies. Several key concepts have matured over the past decade. Among them, those arising from the refinement of mouse models of TAO, early stage investigation into restoring immune tolerance in Graves' disease, and a hard-won acknowledgement that the insulin-like growth factor-I receptor (IGF-IR) might play a critical role in the development of TAO, stand out as important. The therapeutic inhibition of IGF-IR has blossomed into an effective and safe medical treatment. Teprotumumab, a β-arrestin biased agonist monoclonal antibody inhibitor of IGF-IR has been studied in two multicenter, double-masked, placebo-controlled clinical trials demonstrated both effectiveness and a promising safety profile in moderate-to-severe, active TAO. Those studies led to the approval by the US FDA of teprotumumab, currently marketed as Tepezza for TAO. We have also learned far more about the putative role that CD34⁺ fibrocytes and their derivatives, CD34⁺ orbital fibroblasts, play in TAO.

CONCLUSION

The past decade has been filled with substantial scientific advances that should provide the necessary springboard for continually accelerating discovery over the next 10 years and beyond.

Positive effects of selenium supplementation in women with newly diagnosed Hashimoto's thyroiditis in an area with low selenium status

OBJECTIVE

Autoimmune thyroid diseases, including Hashimoto's thyroiditis, are the most common ones among autoimmune diseases. The reported effects of selenium supplementation on the course of Hashimoto's thyroiditis are not consistent. It is therefore important to continue this line of research.

DESIGN

The participants received selenium in the form of sodium selenite(IV) at a dose of 100 µg/day for 6 months.

PATIENTS

Newly diagnosed and previously untreated Hashimoto's thyroiditis with euthyroidism or subclinical hypothyroidism. A total of 36 patients (aged 20 to 52 years) qualified for this study, of whom 29 women were successfully enrolled and completed the intervention.

MEASUREMENTS

Both before and after supplementation the following parameters in serum were tested: anti-thyroid peroxidase antibodies, thyroid function indicators, selenium as well as antioxidant status parameters and other biochemical parameters (lipid profile, glucose). Iodine supply and subjective assessment of physical and psychological health were also monitored.

RESULTS

Selenium supplementation decreased significantly level of anti-thyroid peroxidase antibodies what might have had a stabilizing effect on thyroid function, as values of thyroid parameters were within normal range before and at the end of the study. Mean level of selenium among patients was not different to healthy people in Poland. Median of ioduria was within normal range.

CONCLUSIONS

The study shows a potential way of protective effect of selenium in limiting development of overt hypothyroidism. The increase in the concentrations of Se and SELENOP in the serum of patients verifies successful supplementation and good compliance, but did not affect the antioxidant status parameters measured.

Familial Risk of Hashimoto's Thyroiditis Among First-Degree Relatives: A Population-Based Study in Korea

Background: Few small-scale studies have reported a genetic and familial predisposition in Hashimoto's thyroiditis (HT), however, quantified familial risk estimates from population-level data are unavailable. We aimed to estimate the incidence and familial risk of HT among first-degree relatives (FDR) according to age, sex, and family relationships. Methods: We conducted a population-based study in the general population of Korea from 2002 to 2017. Using the nationwide health insurance database, which has full population coverage and family relationship information, a cohort of 22 million individuals with blood-related FDR comprising 12 million families were followed up for a familial occurrence of HT. Age- and sex-adjusted incidence risk ratios (IRRs) were calculated in individuals with an affected FDR compared with those without an affected FDR. Results: Among 21,940,795 individuals, 234,912 had an HT-affected FDR, of whom 2425 familial cases developed HT with an incidence of 7.12/10,000 person-years. The familial risk for HT was 6.5-fold (95% confidence interval [CI]: 6.24-6.78) higher in individuals with versus without affected FDR. According to relationship, familial risks were IRR 102.71, IRR 7.80, IRR 5.54, and IRR 5.52 with an affected twin, sibling, mother, and father, respectively, and the corresponding incidence (/10,000 person-years) was 115.57, 10.66, 5.73, and 5.91. Same-sex twins had three times higher risk of developing HT than opposite-sex twins (IRR 121.01 vs. 21.46). The sex-specific familial risk was higher in males than females. The risks demonstrated age dependence, being higher in younger age groups. Conclusions: This study represents the largest population-based study of familial HT risk in Asia. We demonstrated elevated familial risk of incident HT among FDR, but with lower magnitude as those observed in previous studies. Familial risk increased with the degree of genetic relatedness among FDR indicating a prominent role of genetic factors in the familial aggregation of HT. Elevated risks in the younger age groups should motivate clinicians to screen people with a family history, especially those <30 years.

The VDR gene confers a genetic predisposition to Graves' disease and Graves' ophthalmopathy in the Southwest Chinese Han population

OBJECTIVE

Graves' disease (GD) is a common autoimmune disease manifesting with diffuse symmetric thyroid gland enlargement, pretibial myxedema, and Graves' ophthalmopathy (GO). Recently, the vitamin D receptor (VDR) gene has been linked to various autoimmune diseases. This study aimed to investigate the association of VDR gene polymorphisms with susceptibility to GD and GO in the Southwest Chinese Han population.

METHODS

A two-stage association study was performed in 1,209 controls and 650 GD patients by PCR-RFLP assay. Real-time PCR and ELISA were carried out to quantify gene expression and cytokine production.

RESULTS

The first-stage study showed that the frequency of VDR/Apa I AA genotype was significantly increased in GD (Pc = 1.67 × 10^-2, OR = 1.98). The second-stage and combined studies confirmed the association of VDR/Apa I with GD (AA genotype: Pc = 3.45 × 10^-4, OR = 1.87; A allele: Pc = 2.62 × 10^-2, OR = 1.20). The stratification analysis showed that GO patients had a higher frequency of the VDR/Apa I AA genotype (Pc = 8.69 × 10^-5, OR = 2.84). Functional experiments showed a decreased VDR expression and TGF-β1 production as well as an increased IL-17 production in VDR/Apa I AA genotype carriers.

CONCLUSION

The VDR/Apa I polymorphism is significantly associated with GD and GO, and it may be involved in the development of GD and GO by influencing VDR mRNA expression levels and the secretion levels of cytokines.

Demographic and Clinical Features of Small-for-Gestational-Age Infants Born to Mothers With Gestational Diabetes Mellitus

We studied the demographic and clinical characteristic, risk factors, outcomes of full-term small-for-gestational-age (SGA) infants born to mothers with gestational diabetes mellitus (GDM) in China. A retrospective case-control study that included 1981 SGA infants was conducted; the demographic and clinical data between SGA infants born to mothers with and without GDM were compared. Of 383 SGA infants born to mothers with GDM, 221 (57.7%) were female, and the incidence of these infants was 1 in 155 live births. The risk of SGA siblings (RR, 1.88; 95% CI, [1.23-2.86]), low 1- and 5-min Apgar scores (RR,2.04 and 4.21; 95%CI [1.05-4.00] and [1.05-16.89], respectively), early thrombocytopenia (RR, 3.39; 95%CI, [1.33-8.64]), hypoglycemia(RR, 2.49; 95%CI, [1.55-3.98]), and hypoxic-ischemic encephalopathy (RR,5.61; 95%CI, [1.25-25.18]) were increased in SGA infants born to mothers with GDM compared to SGA infants born to mothers without GDM. SGA girls born to mothers with GDM had a significantly higher ratio of catch-up growth (CUG) (RR, 1.73; 95%CI, [1.18-2.54]) in the first year of life. These results show that genetic factors may be one of the etiologies of SGA infants born to mothers with GDM; and these infants have more adverse perinatal outcomes compared to SGA infants born to mothers without GDM. SGA girls born to mothers with GDM had accelerated CUG in the first year of life.

Graves' disease

Graves' disease (GD) is an autoimmune disease that primarily affects the thyroid gland. It is the most common cause of hyperthyroidism and occurs at all ages but especially in women of reproductive age. Graves' hyperthyroidism is caused by autoantibodies to the thyroid-stimulating hormone receptor (TSHR) that act as agonists and induce excessive thyroid hormone secretion, releasing the thyroid gland from pituitary control. TSHR autoantibodies also underlie Graves' orbitopathy (GO) and pretibial myxoedema. Additionally, the pathophysiology of GO (and likely pretibial myxoedema) involves the synergism of insulin-like growth factor 1 receptor (IGF1R) with TSHR autoantibodies, causing retro-orbital tissue expansion and inflammation. Although the aetiology of GD remains unknown, evidence indicates a strong genetic component combined with random potential environmental insults in an immunologically susceptible individual. The treatment of GD has not changed substantially for many years and remains a choice between antithyroid drugs, radioiodine or surgery. However, antithyroid drug use can cause drug-induced embryopathy in pregnancy, radioiodine therapy can exacerbate GO and surgery can result in hypoparathyroidism or laryngeal nerve damage. Therefore, future studies should focus on improved drug management, and a number of important advances are on the horizon.

Genetic Polymorphisms on 4q21.1 Contributed to the Risk of Hashimoto's Thyroiditis

Background: Hashimoto's thyroiditis (HT) is a common autoimmune disease characterized by lymphoid infiltration of the thyroid gland, including both T- and B-cells. Early studies have shown that HT is a complex disorder affected by both environmental and genetic factors. Recently, the single nucleotide polymorphism (SNP) rs2276886 associated with the CXCL9 gene was identified as associated with autoimmune thyroid disease susceptibility in Japanese populations. The aim of the present study was to validate this result for HT in a Chinese Han population. Methods: Study subjects, including 688 HT cases and 1456 healthy controls, were recruited, and 10 SNPs located within the CXCL9 gene were genotyped. Genetic association analyses were performed by fitting logistic models. Bioinformatics tools, including RegulomeDB and GTEx were utilized to investigate the functional consequences of the SNPs found to be significantly associated with HT. Results: SNP rs2276886 was identified as significantly associated with the risk of HT (odds ratio [OR] = 1.25, p = 0.0006). No significant expression quantitative trait loci (eQTL) signals could be identified for CXCL9. Significant eQTL signals were found for other genes, including ART3, CXCL10, CXCL11, NAAA, PPEF2, and SCARB2. This SNP physically maps to the CXCL9 gene region; however, further bioinformatic analyses indicated that this SNP might be associated with the gene NAAA. Conclusions: The rs2276886 SNP was found to be significantly associated with HT susceptibility. However, our findings suggest that this SNP which maps to the chromosomal region 4q21.1 likely effects the NAAA gene (as opposed to the CXCL9 gene), but still contributes to the susceptibility to HT in Han Chinese populations.

Antithyroid Peroxidase Antibodies in Multinodular Hashimoto's Thyroiditis Indicate a Variant Etiology

Introduction

Hashimoto's thyroiditis (HT) is a common autoimmune thyroid disorder, which predominantly presents as a diffuse goiter, with few studies which report HT presenting as multinodular goiter, with variable frequencies ranging from 59% to 78.6% especially from south Indian populations. This variant clinical presentation may have diagnostic challenges which require further analysis. Anti-TPO antibodies are more common (90-95%) in Hashimoto's thyroiditis than anti-TG antibodies in Hashimoto's thyroiditis. This study analyzes the clinical features and the correlation of anti-TPO levels with diffuse and multinodular forms of HT.

Material and Methods

This study was conducted in the Department of General Surgery in a tertiary care hospital in south Tamil Nadu. Patients presenting with clinical features of a thyroid disorder were interviewed and given a detailed clinical, radiological examination and guided FNAC. Those patients diagnosed by FNAC as HT were registered and a sample of 3cc of blood was drawn for T3, T4, TSH, and anti-TPO analysis. All the data were tabulated.

Results and Discussion

Of the 212 patients who presented with goiters, 96 were diagnosed by FNAC as having a cytological picture suggestive of Hashimoto's thyroiditis. Of these 96 patients with HT, 46 (47.9%) were multinodular (HT-MNG), 14 (14.58%) were solitary nodules (HT-SNT), and the remaining 36 (37.5%) were diffuse goiters (HT-D). Of the 46 patients who are HT-MNG, 36.9% had elevated anti-TPO-Ab (more than 35.0U/l) and 63.1% had normal/lower values (less than 35.0U/l). But of 36 patients with HT-D, 77.7% had elevated anti-TPO-Ab levels (>35U/l). Chi square statistics was 15.8346 and the p value is 0.0005 (<.05). Eight cases of HT-D and 3 cases of HT-MNG had hyperthyroidism and 3 cases of HT-D had hypothyroidism and all other cases were in euthyroid state.

Conclusion

Patients presenting as multinodular Hashimoto's thyroiditis have low prevalence of elevated anti-TPO-Ab than diffuse HT which suggests that multinodular form of Hashimoto's thyroiditis is a unique clinical entity with etiopathogenesis that is at variance with the diffuse form.

Genome-Wide Association Studies of Autoimmune Thyroid Diseases, Thyroid Function, and Thyroid Cancer

Thyroid diseases, including autoimmune thyroid diseases and thyroid cancer, are known to have high heritability. Family and twin studies have indicated that genetics plays a major role in the development of thyroid diseases. Thyroid function, represented by thyroid stimulating hormone (TSH) and free thyroxine (T4), is also known to be partly genetically determined. Before the era of genome-wide association studies (GWAS), the ability to identify genes responsible for susceptibility to thyroid disease was limited. Over the past decade, GWAS have been used to identify genes involved in many complex diseases, including various phenotypes of the thyroid gland. In GWAS of autoimmune thyroid diseases, many susceptibility loci associated with autoimmunity (human leukocyte antigen [HLA], protein tyrosine phosphatase, non-receptor type 22 [PTPN22], cytotoxic T-lymphocyte associated protein 4 [CTLA4], and interleukin 2 receptor subunit alpha [IL2RA]) or thyroid-specific genes (thyroid stimulating hormone receptor [TSHR] and forkhead box E1 [FOXE1]) have been identified. Regarding thyroid function, many susceptibility loci for levels of TSH and free T4 have been identified through genome-wide analyses. In GWAS of differentiated thyroid cancer, associations at FOXE1, MAP3K12 binding inhibitory protein 1 (MBIP)-NK2 homeobox 1 (NKX2-1), disrupted in renal carcinoma 3 (DIRC3), neuregulin 1 (NRG1), and pecanex-like 2 (PCNXL2) have been commonly identified in people of European and Korean ancestry, and many other susceptibility loci have been found in specific populations. Through GWAS of various thyroid-related phenotypes, many susceptibility loci have been found, providing insights into the pathogenesis of thyroid diseases and disease co-clustering within families and individuals.

Hashimoto's thyroiditis: relative recurrence risk ratio and implications for screening of first-degree relatives

CONTEXT

The relative recurrence risk ratio (λ_R ) for Hashimoto's thyroiditis (HT) has not been widely studied. The age at which thyroid function evaluation should be initiated for relatives of HT patients remains unclear.

OBJECTIVE

To study λ_R and age-related prevalence of HT in first-degree relatives of HT patients.

METHODS

First-degree relatives (n = 861) of 264 HT patients were evaluated for goitre, thyroid function tests, thyroid antibodies (TAb) and urinary iodide concentration (UIC). HT was defined as TAb positivity and hypothyroidism (subclinical/overt). λ_R was calculated as {number of index patients whose relatives (of particular subtype) had HT/number of index patients having relatives of same subtype}÷ population prevalence of HT (5·1%). The age-related prevalence of HT was studied using Kaplan-Meier method.

RESULTS

A total of 861 relatives (205 parents, 336 siblings and 320 offspring) participated in the study. About 38·3% were TAb positive. The prevalence of HT was 16·7% (22·9% in parents, 19·6% in siblings and 9·6% in offspring). TAb positivity (48·3% vs 33·1%) and HT (23·5% vs 13·6%) were significantly more common in the goitrous group (n = 267) vs nongoitrous group. The median UIC for the study population was 182·5 μg/l. Computed λ_R was 9·1 for any one relative being affected, 5·9 for parents, 6·3 for siblings and 3·1 for offspring. The prevalence of HT increased with age and exceeded the adult population prevalence of 5·1% at 20 years in females and 27 years in males.

CONCLUSIONS

Relatives of HT patients have a ninefold increased risk for developing HT as compared to the general population. The risk of developing HT exceeds that of the general population at 20 years in females and 27 years in males.

Development of autoantibodies precedes clinical manifestations of autoimmune diseases: A comprehensive review

The etiology of autoimmune diseases is due to a combination of genetic predisposition and environmental factors that alter the expression of immune regulatory genes through various mechanisms including epigenetics. Both humoral and cellular elements of the adaptive immune system play a role in the pathogenesis of autoimmune diseases and the presence of autoantibodies have been detected in most but not all autoimmune diseases before the appearance of clinical symptoms. In some cases, the presence or levels of these autoantibodies portends not only the risk of developing a corresponding autoimmune disease, but occasionally the severity as well. This observation is intriguing because it suggests that we can, to some degree, predict who may or may not develop autoimmune diseases. However, the role of autoantibodies in the pathogenesis of autoimmune diseases, whether they actually affect disease progression or are merely an epiphenomenon is still not completely clear in many autoimmune diseases. Because of these gaps in our knowledge, the ability to accurately predict a future autoimmune disease can only be considered a relative risk factor. Importantly, it raises the critical question of defining other events that may drive a patient from a preclinical to a clinical phase of disease.

The thyroid, the eyes and the gut: a possible connection

INTRODUCTION

Graves' disease (GD) is an autoimmune disorder responsible for 60-90% of thyrotoxicosis, with an incidence of 1 to 2 cases per 1000 population per year in England. Graves' orbitopathy (GO) is the most frequent extrathyroidal manifestation, not provoked directly by abnormal thyroid hormone levels, but by the consequence of the underlying autoimmune process. The aetiology of autoimmune disorders is due to an interplay between susceptibility genes and environmental factors, such as infections and stress. What triggers the autoimmune reaction to a specific site of the body is not yet clearly understood. The lack of knowledge in GD and GO pathogenesis implicates therapies that only limit damage but do not prevent disease onset.

MATERIAL AND METHODS

We performed on PubMed and the Cochrane Library a literature search for the articles published until July 2016 by using the search terms 'graves disease' and 'microbiome', 'orbitopathy' and 'autoimmune pathogenesis'. Reference lists of relevant studies were hand-searched for additional studies.

CONCLUSION

In this scenario, a Marie Sklodowska-Curie funded project INDIGO ( http://www.indigo-iapp.eu/ ) is investigating the role of the gut bacteria in GD and GO pathogenesis. The gut is the first and the widest area of bacteria access, with the highest concentration of T cells in the human body and trained to react to microorganisms. Interestingly, all the environmental factors involved in GD and GO pathogenesis can alter the balance within the microorganisms located in the gut, and influence the immune system, in particular the proportions of regulatory Treg and inflammatory TH17 cells. It is hoped that investigating GD and GO pathogenesis from this novel aspect will identify new targets for prevention and treatment.

Guidelines for the treatment of childhood-onset Graves' disease in Japan, 2016

Purpose behind developing these guidelines: Over one decade ago, the “Guidelines for the Treatment of Graves’ Disease with Antithyroid Drug, 2006” (Japan Thyroid Association (JTA)) were published as the standard drug therapy protocol for Graves’ disease. The “Guidelines for the Treatment of Childhood-Onset Graves’ Disease with Antithyroid Drug in Japan, 2008” were published to provide guidance on the treatment of pediatric patients. Based on new evidence, a revised version of the “Guidelines for the Treatment of Graves’ Disease with Antithyroid Drug, 2006” (JTA) was published in 2011, combined with the “Handbook of Radioiodine Therapy for Graves’ Disease 2007” (JTA). Subsequently, newer findings on pediatric Graves’ disease have been reported. Propylthiouracil (PTU)-induced serious hepatopathy is an important problem in pediatric patients. The American Thyroid Association’s guidelines suggest that, in principle, physicians must not administer PTU to children. On the other hand, the “Guidelines for the Treatment of Graves’ Disease with Antithyroid Drug, 2011” (JTA) state that radioiodine therapy is no longer considered a “fundamental contraindication” in children. Therefore, the “Guidelines for the Treatment of Childhood-Onset Graves’ Disease with Antithyroid Drug in Japan, 2008” required revision.

Autoimmune thyroid diseases in children

Autoimmune thyroid diseases (AIT) are common in children and may present with a variety of signs and symptoms including: euthyroid goiter, hypothyroidism, or hyperthyroidism. The natural history of AIT may be different in children but in all age groups, there appear to be genetic risk factors and environmental triggers that initiate thyroid autoimmunity. Areas covered: In this review, we summarize recent studies that investigate the genetics and environmental triggers believed to be involved in thyroid autoimmunity. We also discuss the approach and controversies in the treatment of children with AIT. Expert commentary: Much has been learned about the major roles for genetics, cytokines, regulatory lymphocytes, and environmental triggers in CLT but controversies remain.

Consanguinity and the Risk of Hashimoto's Thyroiditis

BACKGROUND

Hashimoto's thyroiditis (HT) is the most common autoimmune thyroid disease that may lead to hypothyroidism due to progressive destruction of the thyroid. The etiology of HT is unclear. However, it is associated with multiple genetic predispositions. Consanguinity has been associated with an increased susceptibility to different inherited conditions. This study investigated the association between consanguinity and risk of HT for the first time.

METHODS

Using a case-control study design, 298 HT patients were compared with two subject groups: (i) 299 participants with non-HT hypothyroidism, and (ii) 298 healthy control participants. The three groups were age and sex matched. Presence of consanguinity among the parents was compared in these groups, and odds ratios (OR) were calculated to establish a correlation.

RESULTS

Consanguinity significantly increased the risk of HT (compared with healthy subjects; OR = 3.3; p < 0.0001). In addition, consanguinity was a significant risk factor for HT compared with non-HT hypothyroidism patients (OR = 2.8; p < 0.0001). However, the prevalence of consanguinity was not significantly different in non-HT hypothyroidism patients and healthy subjects.

CONCLUSIONS

The results suggest that the risk for HT is increased in consanguineous unions, but no significant increase in the risk of non-HT hypothyroidism was observed. However, for more precise risk estimates, larger studies that include different populations may be helpful. These findings highlight the health impact of consanguinity and have applications in empiric risk estimations in genetic counseling, particularly in countries with high rates of consanguineous marriages.

Pooled genome wide association detects association upstream of FCRL3 with Graves' disease

Background

Graves’ disease is an autoimmune thyroid disease of complex inheritance. Multiple genetic susceptibility loci are thought to be involved in Graves’ disease and it is therefore likely that these can be identified by genome wide association studies. This study aimed to determine if a genome wide association study, using a pooling methodology, could detect genomic loci associated with Graves’ disease.

Results

Nineteen of the top ranking single nucleotide polymorphisms including HLA-DQA1 and C6orf10, were clustered within the Major Histo-compatibility Complex region on chromosome 6p21, with rs1613056 reaching genome wide significance (p = 5 × 10⁻⁸). Technical validation of top ranking non-Major Histo-compatablity complex single nucleotide polymorphisms with individual genotyping in the discovery cohort revealed four single nucleotide polymorphisms with p ≤ 10⁻⁴. Rs17676303 on chromosome 1q23.1, located upstream of FCRL3, showed evidence of association with Graves’ disease across the discovery, replication and combined cohorts. A second single nucleotide polymorphism rs9644119 downstream of DPYSL2 showed some evidence of association supported by finding in the replication cohort that warrants further study.

Conclusions

Pooled genome wide association study identified a genetic variant upstream of FCRL3 as a susceptibility locus for Graves’ disease in addition to those identified in the Major Histo-compatibility Complex. A second locus downstream of DPYSL2 is potentially a novel genetic variant in Graves’ disease that requires further confirmation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-3276-z) contains supplementary material, which is available to authorized users.

Helicobacter pylori infection in women with Hashimoto thyroiditis: A case-control study

An association between Helicobacter pylori (H pylori) infection as environmental risk factors for Hashimoto thyroiditis (HT) has been reported. We investigated this hypothesis in women in which HT is more common. Serum immunoglobulin G antibodies against H pylori (enzyme-linked immunosorbent assay), CagA protein (Western blot assay), circulating antibodies to thyroid antigens, mainly thyroperoxidase (TPOAbs) and thyroglobulin (TgAbs), were tested in 101 females with HT and 111 non-HT control women without a history of autoimmune disease. Thyroid function, socioeconomic status at childhood, and family history of thyroid malfunction were also studied. Forty-seven HT women (46.5%) tested seropositive for H pylori versus 48 controls (43.2%; P = 0.63). The prevalence of anti-CagA antibodies was 21.3% in HT-infected patients and 31.2% in infected controls (P = 0.352). Women with HT were older than the controls at a significance level of 0.03, and higher prevalence of hypothyroidism (69% vs 13.5%, respectively) and family history of thyroid malfunction (59% vs 34%, respectively) (P < 0.001 in both). Body mass index, diaphragmatic hernia, peptic ulcer, heartburn, use of proton pump inhibitors, childhood socioeconomic background, and crowding index showed no significant difference between HT-positive or negative individuals. Multivariate analysis demonstrated that H pylori seropositivity was not associated with HT (odds ratio 1.15, 95% confidence interval 0.57-1.83, P = 0.95) and that family thyroid malfunction was independently associated with an increased risk of HT (odds ratio 3.39, 95% confidence interval 1.86-6.18, P < 0.001). No association was found between H pylori infection and HT in women. Family history of thyroid malfunction is a risk factor for HT.

Clinical Relevance of Environmental Factors in the Pathogenesis of Autoimmune Thyroid Disease

Genetic factors contribute for about 70% to 80% and environmental factors for about 20% to 30% to the pathogenesis of autoimmune thyroid disease (AITD). Relatives of AITD patients carry a risk to contract AITD themselves. The 5-year risk can be quantified by the so-called Thyroid Events Amsterdam-score, based on serum thyroid-stimulating hormone, thyroid peroxidase (TPO)-antibodies and family history. Subjects at risk may ask what they can do to prevent development of AITD. This review summarizes what is known about modulation of exposure to environmental factors in terms of AITD prevention. To stop smoking decreases the risk on Graves disease but increases the risk on Hashimoto disease. Moderate alcohol intake provides some protection against both Graves and Hashimoto disease. Low selenium intake is associated with a higher prevalence of thyroid autoimmunity, but evidence that selenium supplementation may lower TPO antibodies and prevent subclinical hypothyroidism remains inconclusive. Low serum vitamin D levels are associated with a higher prevalence of TPO antibodies, but intervention studies with extra vitamin D have not been done yet. Stress may provoke Graves hyperthyroidism but not Hashimoto thyroiditis. Estrogen use have been linked to a lower prevalence of Graves disease. The postpartum period is associated with an increased risk of AITD. Taking together, preventive interventions to diminish the risk of AITD are few, not always feasible, and probably of limited efficacy.

Autoimmune diseases - connecting risk alleles with molecular traits of the immune system

Genome-wide strategies have driven the discovery of more than 300 susceptibility loci for autoimmune diseases. However, for almost all loci, understanding of the mechanisms leading to autoimmunity remains limited, and most variants that are likely to be causal are in non-coding regions of the genome. A critical next step will be to identify the in vivo and ex vivo immunophenotypes that are affected by risk variants. To do this, key cell types and cell states that are implicated in autoimmune diseases will need to be defined. Functional genomic annotations from these cell types and states can then be used to resolve candidate genes and causal variants. Together with longitudinal studies, this approach may yield pivotal insights into how autoimmunity is triggered.

Genomics and phenomics of Hashimoto's thyroiditis in children and adolescents: a prospective study from Southern India

BACKGROUND

Hashimoto's thyroiditis (HT) is the commonest cause of acquired hypothyroidism in children and adolescents in iodine non-endemic areas. The genetic analysis in HT shows two types of susceptibility genes-immune regulatory and thyroid specific genes. The exact genotype-phenotypic correlations and risk categorization of hypothyroid phenotypes resulting from these known mutations are largely speculative. The genetic studies in pediatric HT are very sparse from Indian sub-continent. In this context, we analysed the prevalence of TPO, NIS and DUOX2 gene mutations along with genotype-phenotype correlations in hypothyroid children with HT.

METHODS

This is inter-disciplinary study conducted by collaboration between a tertiary care endocrinology hospital, biochemistry department of a teaching medical institute and genetics lab. In this prospective study, we employed 8 sets of primers and screened for 142 known single nucleotide polymorphisms in TPO, NIS, DUOX2 genes. The subjects were children and adolescents with hypothyroidism due to HT. Congenital hypothyroidism, iodine deficiency and dyshormonogenetic hypothyroidism cases were excluded.

RESULTS

We detected 8 mutations in 7/20 (35%) children in the entire cohort (6 in NIS and 2 in TPO genes. No mutations were observed in DUOX2 gene. All our mutations were localized in introns and we found none in exons. Except for bi-allelic, synonymous polymorphism of TPO gene in child No. 18, all other mutations were heterozygous in nature. Genotype-phenotype correlations show that our mutations significantly expressed the presence of associated autoimmune manifestations and existence of family history. Clinical phenotypes of painful thyroiditis, severity of hypothyroidism and absence of goiter were statistically significant in the presence of these mutations. But, they could not reach significance on multivariate analysis.

CONCLUSIONS

NIS gene followed by TPO mutations appears to be most prevalent mutations in HT amongst South Indian children and these mutations significantly influenced phenotypic expressions such as severity of hypothyroidism, goiter, auto-immune manifestations and family history.

Pediatric Graves' disease: decisions regarding therapy

PURPOSE OF REVIEW

Graves' disease is the most common cause of hyperthyroidism in the pediatric population. It occurs more often in adolescence and in girls; however, prepubertal children tend to have more severe disease, require longer medical therapy, and have a lower rate of remission as compared with pubertal children. The choice of which of the three therapeutic options to use (medical therapy, radioactive iodine ablation, or surgery) must be individualized. This update will focus on the current diagnostic and treatment modalities available, as well as address the controversy that exists with regards to permanent therapy.

RECENT FINDINGS

The diagnosis of Graves' disease is often made clinically. With the development of second-generation and third-generation thyroid-stimulating hormone receptor antibody assays, it can be more reliably confirmed. An improved understanding of the underlying autoimmune process and genetics is underway; however, remission rates in children and adolescents remain low. Because of its ease of administration and long-term follow-up, there is a trend towards permanent therapy with radioactive iodine ablation when remission cannot be achieved with medical therapy.

SUMMARY

New genes and susceptibility loci have been identified with the hope of better understanding the refractory nature of Graves' disease. Despite the low rates of remission, permanent therapy with radioactive iodine remains a good option.

Immunogenetics of autoimmune thyroid diseases: A comprehensive review

Both environmental and genetic triggers factor into the etiology of autoimmune thyroid disease (AITD), including Graves' disease (GD) and Hashimoto's thyroiditis (HT). Although the exact pathogenesis and causative interaction between environment and genes are unknown, GD and HT share similar immune-mediated mechanisms of disease. They both are characterized by the production of thyroid autoantibodies and by thyroidal lymphocytic infiltration, despite being clinically distinct entities with thyrotoxicosis in GD and hypothyroidism in HT. Family and population studies confirm the strong genetic influence and inheritability in the development of AITD. AITD susceptibility genes can be categorized as either thyroid specific (Tg, TSHR) or immune-modulating (FOXP3, CD25, CD40, CTLA-4, HLA), with HLA-DR3 carrying the highest risk. Of the AITD susceptibility genes, FOXP3 and CD25 play critical roles in the establishment of peripheral tolerance while CD40, CTLA-4, and the HLA genes are pivotal for T lymphocyte activation and antigen presentation. Polymorphisms in these immune-modulating genes, in particular, significantly contribute to the predisposition for GD, HT and, unsurprisingly, other autoimmune diseases. Emerging evidence suggests that single nucleotide polymorphisms (SNPs) in the immunoregulatory genes may functionally hinder the proper development of central and peripheral tolerance and alter T cell interactions with antigen presenting cells (APCs) in the immunological synapse. Thus, susceptibility genes for AITD contribute directly to the key mechanism underlying the development of organ-specific autoimmunity, namely the breakdown in self-tolerance. Here we review the major immune-modulating genes that are associated with AITD and their potential functional effects on thyroidal immune dysregulation.

Role of genetic and non-genetic factors in the etiology of Graves' disease

In spite of the advancements in understanding the pathogenic mechanisms of Graves' disease (GD), its ultimate cause remains elusive. The majority of investigators agree that GD is likely a multifactorial disease, due to a complex interplay of genetic and non-genetic factors that lead to the loss of immune tolerance to thyroid antigens and to the initiation of a sustained autoimmune reaction. Twin and family studies support a role of genetic factors, among which the HLA complex, CD40, CTLA-4, PTPN22, FCRL3, thyroglobulin, and the TSH receptor may be involved. Among non-genetic factors, iodine, infections, psychological stress, gender, smoking, thyroid damage, vitamin D, selenium, immune modulating agents, and periods of immune reconstitution may contribute the development of the diseases. Here we review in detail the respective role of genetic and non-genetic factors in the etiology of GD, taking advantage of the great bulk of data generated especially over the past 30 years.

Mechanisms of autoimmune thyroid diseases: from genetics to epigenetics

Recent advances in our understanding of genetic-epigenetic interactions have unraveled new mechanisms underlying the etiology of complex autoimmune diseases. Autoimmune thyroid diseases (AITDs) are highly prevalent, affecting 1% to 5% of the population. The major AITDs include Graves disease (GD) and Hashimoto's thyroiditis (HT); although these diseases contrast clinically, their pathogenesis involves shared immunogenetic mechanisms. Genetic data point to the involvement of both shared and unique genes. Among the shared susceptibility genes, HLA-DRβ1-Arg74 (human leukocyte antigen DR containing an arginine at position β74) confers the strongest risk. Recent genome-wide analyses have revealed new putative candidate genes. Epigenetic modulation is emerging as a major mechanism by which environmental factors interact with AITD susceptibility genes. Dissecting the genetic-epigenetic interactions underlying the pathogenesis of AITD is essential to uncover new therapeutic targets.

Autoimmune thyroid disorders

Purpose of Review. Studies have been published in the field of autoimmune thyroid diseases since January 2005. The review is organized into areas of etiology, autoimmune features, autoantibodies, mechanism of thyroid cell injury, B-cell responses, and T-cell responses. Also it reviews the diagnosis and the relationship between autoimmune thyroid disease, neoplasm, and kidney disorders. Recent Findings. Autoimmune thyroid diseases have been reported in people living in different parts of the world including North America, Europe, Baalkans, Asia, Middle East, South America, and Africa though the reported figures do not fully reflect the number of people infected per year. Cases are unrecognized due to inaccurate diagnosis and hence are treated as other diseases. However, the most recent studies have shown that the human autoimmune thyroid diseases (AITDs) affect up to 5% of the general population and are seen mostly in women between 30 and 50 years. Summary. Autoimmune thyroid disease is the result of a complex interaction between genetic and environmental factors. Overall, this review has expanded our understanding of the mechanism involved in pathogenesis of AITD and the relationship between autoimmune thyroid disease, neoplasm, and kidney disease. It has opened new lines of investigations that will ultimately result in a better clinical practice.

Graves' disease in monozygotic twins - a case report

BACKGROUND

Autoimmune thyroid diseases including Graves' disease and Hashimoto's thyroiditis are caused by immune response to self-thyroid antigens. The rare situation of hyperthyroidism with Graves' disease in twins has been reported in a very few case reports in literature.

CASE PRESENTATION

We present monozygotic female twins developing consecutively Graves' disease within five years. One year before the diagnosis of Graves' disease was established in the first twin, the mother developed a toxic thyroid nodule with hyperthyroidism leading to hemi thyroidectomy. Both the mother and the twins were cigarette smokers. The twins were treated with carbamizole and this therapy led to normalization of thyroid stimulating hormone and thyroxine.

CONCLUSION

This case report supports the hypothesis that a genetic factor as well as an environmental factor (cigarette smoking) might be of great importance in the aetiology of Graves' disease.

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.

Involvement of stress in the pathogenesis of autoimmune thyroid disease: a prospective study

BACKGROUND

An association between stress and autoimmune thyroid disease (AITD) (especially Graves' hyperthyroidism) has been reported, but all studies so far on this topic have been retrospective.

OBJECTIVE

To evaluate prospectively the relationship between stress and (i) de novo occurrence of thyroid antibodies and (ii) development of overt autoimmune hyper-/hypothyroidism.

STUDY DESIGN

Two nested case-control studies in a prospective cohort of 790 euthyroid women who were 1st or 2nd degree relatives of AITD patients. Follow-up was five year, with annual assessments including questionnaires on stressful life events, daily hassles, and mood. In study A, cases were subjects who developed TPO-Ab but remained euthyroid during follow-up (called event). In study B, cases were subjects who developed overt hypothyroidism (TSH>5.7 mU/l and FT4<9.3 pmol/l) or overt hyperthyroidism (TSH<0.4 mU/l and FT4>20.1 pmol/l) during follow-up (called event). For each case, two controls were selected, matched for age and duration of follow-up; controls in study A remained TPO-Ab negative, and in study B remained without overt hyper-/hypothyroidism.

OUTCOMES

Contrast in questionnaire responses between cases and controls at baseline, at one year prior to the event and at time of event.

RESULTS

Exposure to stress was not different between subjects who developed or did not develop TPO-Ab (study A). No differences were observed in stress questionnaires between hyper-/hypothyroid cases and controls at any time point, but hypothyroid cases had less negative feelings than controls at the time of diagnosis (study B).

CONCLUSION

The data suggest that stress is not involved in the pathogenesis of AITD.

Hashimoto's Thyroiditis: From Genes to the Disease

Hashimoto's thyroiditis (HT) is the most prevalent autoimmune thyroid disorder. Intrathyroidal lymphocytic infiltration is followed by a gradual destruction of the thyroid gland which may lead to subclinical or overt hypothyroidism. Biochemical markers of the disease are thyroid peroxidase and/or thyroglobulin autoantibodies in the serum which are present with a higher prevalence in females than in males and increase with age. Although exact mechanisms of aetiology and pathogenesis of the disorder are not completely understood, a strong genetic susceptibility to the disease has been confirmed predominantly by family and twin studies. Several genes were shown to be associated with the disease occurrence, progression, and severity. Genes for human leukocyte antigen, cytotoxic T lymphocyte antigen-4, protein tyrosine phosphatase nonreceptor-type 22, thyroglobulin, vitamin D receptor, and cytokines are considered to be of utmost importance. Amongst endogenous factors for the disease development, the attention is focused predominantly on female sex, pregnancy with postpartum period and fetal microchimerism. Environmental factors influencing HT development are iodine intake, drugs, infections and different chemicals. Disturbed self-tolerance accompanied by the increased antigen presentation is a prerequisite for the HT occurrence, whereas proper interaction of thyroid cells, antigen presenting cells, and T cells are necessary for the initiation of thyroid autoimmunity. Secreted cytokines lead predominantly to T-helper type 1 (Th1) response as well as to Th 17 response which has only recently been implicated. Final outcome of HT is thyroid destruction which is mostly a consequence of the apoptotic processes combined with T-cell mediated cytotoxicity.

Environmental exposures and autoimmune thyroid disease

BACKGROUND

Environmental exposures, ranging from perchlorate in rocket fuel to polychlorinated biphenols, have been shown to influence thyroid function. Although most of these agents are associated with reduced thyroid hormone levels or impaired thyroid hormone action, a number of environmental exposures confer an increased risk of autoimmune thyroid disease.

SUMMARY

Factors that increase autoimmune thyroid disease risk include radiation exposure, both from nuclear fallout and medical radiation, increased iodine intake, as well as several contaminants in the environment that influence the thyroid. Although approximately 70% of the risk for developing autoimmune thyroid disease is attributable to genetic background, environmental triggers are thought to play a role in the development of autoimmune thyroid disease in susceptible individuals.

CONCLUSIONS

Understanding the association of environmental agents with thyroid dysfunction can be utilized to reduce the risk to populations. Knowledge of the specific factors that trigger autoimmune thyroid disease and their mode of action, however, may also inform risk reduction in the individual patient. These factors are especially relevant for those at increased risk of autoimmune thyroid disease based on family history.

The genetics of the thyroid stimulating hormone receptor: history and relevance

BACKGROUND

The thyroid stimulating hormone receptor (TSHR) is the key regulator of thyrocyte function. The gene for the TSHR on chromosome 14q31 has been implicated as coding for the major autoantigen in the autoimmune hyperthyroidism of Graves' disease (GD) to which T cells and autoantibodies are directed.

SUMMARY

The TSHR is a seven-transmembrane domain receptor that undergoes complex posttranslational processing. In this brief review, we look at the genetics of this important autoantigen and its influence on a variety of tissue functions in addition to its role in the induction of GD.

CONCLUSIONS

There is convincing evidence that the TSH receptor gene confers increased susceptibility for GD, but not Hashimoto's thyroiditis. GD is associated with polymorphisms in the intron 1 gene region. How such noncoding nucleotide changes influence disease susceptibility remains uncertain, but is likely to involve TSHR splicing variants and/or microRNAs arising from this gene region. Whether such influences are confined to the thyroid gland or whether they influence cell function in the many extrathyroidal sites of TSHR expression remains unknown.