The genetics of Graves' disease

Exploring the bidirectional relationship between metabolic syndrome and thyroid autoimmunity: a Mendelian randomization study

Background

Observational studies have reported a possible association between metabolic syndrome (MetS) and thyroid autoimmunity. Nevertheless, the relationship between thyroid autoimmunity and MetS remains unclear. The objective of this research was to assess the causal impact of MetS on thyroid autoimmunity through the utilization of Mendelian randomization (MR) methodology.

Methods

We performed bidirectional MR to elucidate the causal relationship between MetS and their components and thyroid autoimmunity (positivity of TPOAb). Single nucleotide polymorphisms (SNPs) of MetS and its components were obtained from the publicly available genetic variation summary database. The Thyroidomics Consortium conducted a genome-wide association analysis, which provided summary-level data pertaining to thyroid autoimmunity. The study included several statistical methods, including the inverse variance weighting method (IVW), weighted median, simple mode, weight mode, and MR-Egger methods, to assess the causal link. In addition, to ensure the stability of the results, a sensitivity analysis was conducted.

Results

IVW showed that MetS reduced the risk of developing thyroid autoimmunity (OR = 0.717, 95% CI = 0.584 - 0.88, P = 1.48E-03). The investigation into the causative association between components of MetS and thyroid autoimmune revealed a statistically significant link between triglycerides levels and the presence of thyroid autoimmunity (IVW analysis, OR = 0.603, 95%CI = 0.45 -0.807, P = 6.82E-04). The reverse analysis did not reveal any causal relationship between thyroid autoimmunity and MetS, including its five components.

Conclusions

We have presented new genetic evidence demonstrating that MetS and its triglyceride components may serve as potential protective factors against thyroid autoimmunity.

Significance of HLA in Graves' disease and Graves' orbitopathy in Asian and Caucasian populations - a systematic review

Introduction

Graves' disease (GD) and Graves' orbitopathy (GO) development were suspected to be HLA-related in both Asian and Caucasian populations. However, most studies were performed with application of serological methods or low resolution genetic typing, which led to inconsistent results even among the same population. The present review is intended to summarize the state-of-art knowledge on the HLA significance in GD and GO in Asians and Caucasians, as well as to find the most significant alleles for each of the populations.

Methods

PubMed was searched for relevant articles using the following search terms: HLA plus thyroid-associated ophthalmopathy or Graves' disease or Graves' orbitopathy or thyroid eye disease or thyroid-associated orbitopathy.

Results

In Asian population GD was found to be associated mostly with B*46:01, DPB1*05:01, DRB1*08:02/03, DRB1*16:02, DRB1*14:03, DRB1*04:05, DQB1*05:02 and DQB1*03:03, while DRB1*07:01, DRB1*01:01, DRB1*13:02, DRB1*12:02 are potentially protective. HLA-B*38:02, DRB1*16:02, DQA1*01:02, DQB1*05:02 can be considered associated with increased risk of GO in Asians, while HLA-B*54:01 may play protective role. In Caucasians, C*07:01, DQA1*05:01, DRB1*03, DQB1*02:01 are associated with GD risk while DRB1*07:01, DQA1*02:01 may be protective. Significance of HLA in the course of GD and novel aspects of HLA amino acid variants and potential HLA-based treatment modalities were also discussed.

Recurrence of Graves' Disease: What Genetics of HLA and PTPN22 Can Tell Us

BACKGROUND

Approximately half of patients diagnosed with Graves' disease (GD) relapse within two years of thyreostatic drug withdrawal. It is then necessary to decide whether to reintroduce conservative treatment that can have serious side effects, or to choose a radical approach. Familial forms of GD indicate a significant genetic component. Our aim was to evaluate the practical benefits of HLA and PTPN22 genetic testing for the assessment of disease recurrence risk in the Czech population.

METHODS

In 206 patients with GD, exon 2 in the HLA genes DRB1, DQA1, DQB1 and rs2476601 in the gene PTPN22 were sequenced.

RESULTS

The risk HLA haplotype DRB1*03-DQA1*05-DQB1*02 was more frequent in our GD patients than in the general European population. During long-term retrospective follow-up (many-year to lifelong perspective), 87 patients relapsed and 26 achieved remission lasting over 2 years indicating a 23% success rate for conservative treatment of the disease. In 93 people, the success of conservative treatment could not be evaluated (thyroidectomy immediately after the first attack or ongoing antithyroid therapy). Of the examined genes, the HLA-DQA1*05 variant reached statistical significance in terms of the ability to predict relapse (p=0.03). Combinations with either both other HLA risk genes forming the risk haplotype DRB1*03-DQA1*05-DQB1*02 or with the PTPN22 SNP did not improve the predictive value.

CONCLUSION

the DQA1*05 variant may be a useful prognostic marker in patients with an unclear choice of treatment strategy.

General properties of autoimmune thyroid diseases and associated morbidities

Background Autoimmune thyroid diseases (ATDs) can be classified into two basic diseases: Graves' disease (GD) and Hashimoto's thyroiditis (HT). Here, we review the effectiveness of laboratory and imaging methods used for the early diagnosis of ATD and draw attention to methods that may improve screening. Methods Retrospective data of 142 patients diagnosed with ATD between January 2010 and December 2015 at our paediatric endocrinology clinic were used. Sociodemographic characteristics, clinical findings, treatments and follow-up data of patients were statistically evaluated. Results Of the ATD cases, 81% (n = 115) were female. The median age was 12.5 ± 3.5 (range 1-17) years and 91% (n = 129) of patients were in puberty. There was a significant positive correlation between the height (standard deviation score) and follow-up time for patients with HT (r = 0.156, p < 0.01). Thyroglobulin antibody (TgAb) positivity was found in 75% (45/60) of females with a positive maternal ATD history (p = 0.045). Thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4) values were significantly altered during the treatment follow-up period in female patients with GD and HT, while only fT4 values were found to be significantly altered in boys with HT. Conclusion Although GD and HT have similar mechanisms, they differ in terms of treatment duration and remission and relapse frequencies. Ultrasonography (USG) screening is a non-invasive procedure that is suitable for all patients with ATD. Based on our results, TgAb could be useful in the screening of girls with a history of maternal ATD.

Linkage Analysis of the Chromosome 5q31-33 Region Identifies JAKMIP2 as a Risk Factor for Graves' Disease in the Chinese Han Population

Background

This study aimed to investigate susceptibility to Graves’s disease and the association with the 5q32–33.1 region on chromosome 5 in a Chinese Han population.

Material/Methods

Eighty Chinese Han multiplex families included first-degree and second-degree relatives with Graves’ disease. Eight microsatellite markers on chromosome 5 at the 5q32–33.1 region underwent linkage analysis and the association between the regions D5S1480–D5S2014 were studied.

Results

The maximal heterogeneity logarithm of the odds (HLOD) score of D5S2090 was 4.29 (α=0.42) and of D5S2014 was 4.01 (α=0.34). A nonparametric linkage (NPL) score of 3.14 (P<0.001) was found for D5S2014. The D5S1480–D5S2014 region on chromosome 5 was associated with Graves’ disease, with eight haplotype domains. There were significant differences in the sixth and eighth haplotype domains between patients with Graves’ disease compared with normal individuals. Tagging single nucleotide polymorphisms (SNPs) of the sixth and eighth haplotype domains showed that individuals with SNP62 (rs12653715 G/C) who were GG homozygous had a significantly increased risk of Graves’ disease compared GC heterozygous or CC homozygous individuals. The transmission disequilibrium test (TDT) indicated that SNP62 (rs12653715) and SNP63 (rs12653081) loci in the Janus kinase and microtubule interacting protein 2 (JAKMIP2) gene showed dominant transmission from heterozygous parents to the affected offspring, and SNPs in the secretoglobin family 3A member 2 (SCGB3A2) gene showed no transmission disequilibrium. The haplotype JAKMIP2-1 was identified as being particularly significant.

Conclusions

JAKMIP2 gene polymorphism require further study as potential risk factors for Graves’ disease in the Chinese Han population.

Genetic predictors of the development and recurrence of Graves' disease

Graves' disease affects approximately 3 % of women and 0.5 % of men. The first-choice therapy is based on the administration of thyrostatic drugs. However, approximately half of patients relapse within two years of discontinuation. These patients must then decide whether to re-initiate thyrostatics, which may have serious side effects, or to undergo surgery or radioiodine treatment. Familial forms of Graves' disease indicate a significant genetic component, with twin studies demonstrating a contribution of genetic factors up to 70-80 %. The autoimmune nature of the disease involves the human leukocyte antigen (HLA) complex, which has a decisive impact on each individual's immune response. Within HLA, some variants of the DRB1, DQA1 and DQB1 genes appear to be possible predictors of the development and recurrence of Graves' disease. Outside the HLA region, many variants of immunocompetent genes have also been identified as potential Graves' disease predictors. Apart from the immune system, some thyroid-specific genes have been described in relation to the disease. Here, we present current knowledge regarding the genetic components involved in the development and recurrence of Graves' disease. Further, we present original pilot results from a cohort of Czech Graves' disease patients regarding the HLA variants.

Nuclear medicine imaging and therapy: gender biases in disease

Gender-based medicine is medical research and care conducted with conscious consideration of the sex and gender differences of subjects and patients. This issue of Seminars is focused on diseases for which nuclear medicine is part of routine management and for which the diseases have sex- or gender-based differences that affect incidence or pathophysiology and that thus have differences that can potentially affect the results of the relevant nuclear medicine studies. In this first article, we discuss neurologic diseases, certain gastrointestinal conditions, and thyroid conditions. The discussion is in the context of those sex- or gender-based aspects of these diseases that should be considered in the performance, interpretation, and reporting of the relevant nuclear medicine studies. Cardiovascular diseases, gynecologic diseases, bone conditions such as osteoporosis, pediatric occurrences of some diseases, human immunodeficiency virus-related conditions, and the radiation dose considerations of nuclear medicine studies are discussed in the other articles in this issue.

Identification of novel genetic Loci associated with thyroid peroxidase antibodies and clinical thyroid disease

Autoimmune thyroid diseases (AITD) are common, affecting 2-5% of the general population. Individuals with positive thyroid peroxidase antibodies (TPOAbs) have an increased risk of autoimmune hypothyroidism (Hashimoto's thyroiditis), as well as autoimmune hyperthyroidism (Graves' disease). As the possible causative genes of TPOAbs and AITD remain largely unknown, we performed GWAS meta-analyses in 18,297 individuals for TPOAb-positivity (1769 TPOAb-positives and 16,528 TPOAb-negatives) and in 12,353 individuals for TPOAb serum levels, with replication in 8,990 individuals. Significant associations (P<5×10(-8)) were detected at TPO-rs11675434, ATXN2-rs653178, and BACH2-rs10944479 for TPOAb-positivity, and at TPO-rs11675434, MAGI3-rs1230666, and KALRN-rs2010099 for TPOAb levels. Individual and combined effects (genetic risk scores) of these variants on (subclinical) hypo- and hyperthyroidism, goiter and thyroid cancer were studied. Individuals with a high genetic risk score had, besides an increased risk of TPOAb-positivity (OR: 2.18, 95% CI 1.68-2.81, P = 8.1×10(-8)), a higher risk of increased thyroid-stimulating hormone levels (OR: 1.51, 95% CI 1.26-1.82, P = 2.9×10(-6)), as well as a decreased risk of goiter (OR: 0.77, 95% CI 0.66-0.89, P = 6.5×10(-4)). The MAGI3 and BACH2 variants were associated with an increased risk of hyperthyroidism, which was replicated in an independent cohort of patients with Graves' disease (OR: 1.37, 95% CI 1.22-1.54, P = 1.2×10(-7) and OR: 1.25, 95% CI 1.12-1.39, P = 6.2×10(-5)). The MAGI3 variant was also associated with an increased risk of hypothyroidism (OR: 1.57, 95% CI 1.18-2.10, P = 1.9×10(-3)). This first GWAS meta-analysis for TPOAbs identified five newly associated loci, three of which were also associated with clinical thyroid disease. With these markers we identified a large subgroup in the general population with a substantially increased risk of TPOAbs. The results provide insight into why individuals with thyroid autoimmunity do or do not eventually develop thyroid disease, and these markers may therefore predict which TPOAb-positives are particularly at risk of developing clinical thyroid dysfunction.

The new perspectives on genetic studies of type 2 diabetes and thyroid diseases

Recently, genome-wide association studies (GWAS) have led to the discovery of hundreds of susceptibility loci that are associated with complex metabolic diseases, such as type 2 diabetes and hyperthyroidism. The majority of the susceptibility loci are common across different races or populations; while some of them show ethnicity-specific distribution. Though the abundant novel susceptibility loci identified by GWAS have provided insight into biology through the discovery of new genes or pathways that were previously not known, most of them are in introns and the associated variants cumulatively explain only a small fraction of total heritability. Here we reviewed the genetic studies on the metabolic disorders, mainly type 2 diabetes and hyperthyroidism, including candidate genes-based findings and more recently the GWAS discovery; we also included the clinical relevance of these novel loci and the gene-environmental interactions. Finally, we discussed the future direction about the genetic study on the exploring of the pathogenesis of the metabolic diseases.

Association of Hashimoto's thyroiditis with cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) and inducible co-stimulator (ICOS) genes in a Kuwaiti population

Analysing two CTLA-4 markers [exon 1 A49G single nucleotide polymorphism (SNP) and exon 4 3'UTR (AT)n repeat] and the ICOS intron 4 (GT)n marker for their potential association with HT, and exploring the effect of the tested SNPs on the CTLA-4 isoform expression at the mRNA and protein levels. Total of 270 age-gender-ethnically matched subjects were genotyped by fluorescent-labelled restriction fragment length polymorphism, multiplex PCR, and fragment analysis. Sequencing was used to confirm the genotyping results. Expression of the full-length and soluble CTLA-4 mRNAs analysed using real-time PCR. Sera from subjects were screened for sCTLA-4 using ELISA. Tested subjects revealed ten alleles and sixteen genotypes of CTLA-4 3'UTR(AT)n. The 3'UTR(AT)n was significantly associated with HT: allele (AT)15 and genotype 15/15 were found to cause susceptibility to HT (P = 0.004, OR = 2.13, 95 % CI = 1.26-3.58 and P = 0.029, OR = 2.77, 95 % CI = 1.1-6.94, respectively), whereas allele (AT)6 and genotype 6/6 were found to be protective of HT (P = 0.00002, OR = 0.36, 95 % CI = 0.227-0.57 and P = 0.001, OR = 0.357, 95 % CI = 0.1980.64, respectively). SNP A49G and ICOS(GT)n revealed no significant association with HT (P > 0.05). The expression of sCTLA-4 was inversely proportional to the number of 3'UTR(AT)n repeats, with heterozygous and longer (AT)n repeats showing lower levels of sCTLA-4 mRNA than those with shorter alleles in HC and HT (P = 0.001 and P = 0.04, respectively). Significant increase in the serum level of sCTLA-4 was observed in HT patients compared with the HC (P = 0.0007). The novel finding in our study is that the CTLA-4 3'UTR(AT)n proven to be a key player in the pathogenesis of HT.

Remapping the type I diabetes association of the CTLA4 locus

The Type I Diabetes Genetics Consortium genotyped 24 single-nucleotide polymorphisms (SNPs) in the CTLA4 locus in 2298 type I diabetes (T1D) nuclear families (11 159 individuals, 5003 affected) to evaluate the recognized T1D association. The 24 CTLA4 SNPs span approximately 43 kb from the 5' flanking to 3' flanking region of the gene in the middle of an extended region of linkage disequilibrium of more than 100 kb. The genotyping was performed using two technologies (Illumina GoldenGate and Sequenom iPlex) on the same samples. The genotype calls by both the methods were highly consistent (the majority >99%). Previously reported T1D association from both the +49G>A and the CT60 SNPs was replicated. The reported association of the -319C>T SNP was not replicated. Although associated with T1D risk, it is likely that neither SNP is causative, as the peak of T1D association was from the SNP rs231727 at 3' flanking of the CTLA4 gene. Comprehensive resequencing and fine mapping of the CTLA4 region are still needed to clarify the causal variants.

Association of the thyroid stimulating hormone receptor gene (TSHR) with Graves' disease

Graves' disease (GD) is a common autoimmune disease (AID) that shares many of its susceptibility loci with other AIDs. The thyroid stimulating hormone receptor (TSHR) represents the primary autoantigen in GD, in which autoantibodies bind to the receptor and mimic its ligand, thyroid stimulating hormone, causing the characteristic clinical phenotype. Although early studies investigating the TSHR and GD proved inconclusive, more recently we provided convincing evidence for association of the TSHR region with disease. In the current study, we investigated a combined panel of 98 SNPs, including 70 tag SNPs, across an extended 800 kb region of the TSHR to refine association in a cohort of 768 GD subjects and 768 matched controls. In total, 28 SNPs revealed association with GD (P < 0.05), with strongest SNP associations at rs179247 (chi(2) = 32.45, P = 8.90 x 10(-8), OR = 1.53, 95% CI = 1.32-1.78) and rs12101255 (chi(2) = 30.91, P = 1.95 x 10(-7), OR = 1.55, 95% CI = 1.33-1.81), both located in intron 1 of the TSHR. Association of the most associated SNP, rs179247, was replicated in 303 GD families (P = 7.8 x 10(-4)). In addition, we provide preliminary evidence that the disease-associated genotypes of rs179247 (AA) and rs12101255 (TT) show reduced mRNA expression ratios of flTSHR relative to two alternate TSHR mRNA splice variants.

The role of genetics in Graves' disease and thyroid orbitopathy

Graves' disease is a complex autoimmune disorder characterized by multiple systemic manifestations of overproduction of thyroid hormone, and in some cases, orbitopathy. The etiology of this disorder is multifactorial, involving heritable abnormalities of immune regulation as well as environmental triggers. The goal of this paper is to provide a review of recent research investigating candidate genes involved in the pathophysiology of both Graves' disease per se and of thyroid orbitopathy.

The common variants of E-selectin gene in Graves' disease

Adhesion molecules are involved in cell invasion in autoimmune thyroid disease. It was also reported that patients with untreated Graves' disease (GD) had high serum level of soluble form of E-selectin (sE-selectin), the concentration of which correlated with the activity of the disease. The aim of the present study was to elucidate whether the common variants in E-selectin gene (SELE) were associated with the development of GD. Six tagSNPs within SELE were studied in 297 patients with GD and 208 healthy subjects in Chinese population. Our data showed that common SELE variants were associated with GD (P=0.012-0.036). Haplotype analysis of the single nucleotide polymorphisms revealed an association of a haplotype ATAACC with GD (P=0.005). Furthermore, quantitative trait analysis showed a significant association of SELE haplotype with sE-selectin levels (P=0.0438). This study therefore could provide us to a certain degree the insight that common SELE variants may be associated with susceptibility to GD in Chinese population, though the limitation of sample size and multiple test problems exists.

Evaluation and Management of Graves' Orbitopathy

Graves' orbitopathy, also known as Graves' ophthalmopathy or thyroid eye disease, is a potentially progressive but generally self-limited autoimmune process associated with hyperthyroidism. It is the most common cause of proptosis and the most common orbital inflammatory disorder in adults.

Lack of a genetic association between the CTLA-4 gene and Graves' disease in Koreans

Graves' disease (GD) is a complex autoimmune thyroid disease with a strong genetic component. The cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) gene, which encodes a negative regulator of the T-lymphocyte immune response, has been reported to be associated and/or linked to GD. Therefore, in order to determine the contribution of CTLA-4 in GD in Koreans, we genotyped the five single nucleotide Polymorphisms (SNPs) of the CTLA-4 gene, including +49, CT60, JO31, JO30, and JO27-1 in Korean spatients with GD and healthy controls. Two hundred seventy-eight Korean patients with GD from the Thyroid Clinic and 472 healthy controls from the Health Screening Center of Samsung Medical Center were enrolled in this study. The +49A/G polymorphism of the CTLA-4 gene exon 1 was sequenced directly and the genotyping of the remaining 4 SNPs was accomplished using a Snapshot. In addition, the association of haplotypes with a combination of the above markers was also examined in 278 Korean patients with GD and 472 controls. The results showed that there was no significant positive association between any individual SNP or haplotype comprising of the four 3 untranslated region (UTR) SNPs (CT60, JO31, JO30, and JO27-1) and GD. These data provide little support for CTLA-4 to play a role in the genetic predisposition to GD in Koreans. However, it will be necessary to validate or replicate this association in other independent large-size ethnic groups.

The association between HLA class II haplotype with Graves' disease in Thai population

The distribution of HLA-DRB1, -DQA1 and -DQB1 alleles were analysed in 124 Graves' disease (GD) patients compared to 124 normal controls in order to identify the alleles/haplotypes associated with GD in Thai population. The DRB1*1602-DQA1*0102-DQB1*0502 haplotype was significantly increased in GD patients (P = 0.0209, OR = 2.55). DRB1*07-DQA1*0201-DQB1*0201 haplotype (P = 0.039, OR = 0.32) and HLA-DRB1*12-DQA1*0601-DQB1*0301 haplotype (P = 0.0025, OR = 0.28) were significantly decreased in GD patients. Interestingly, a protective DRB1*07 allele in Thai population lacks an arginine at position 74 similar to DRB1*0311 (a protective allele in Caucasians). A significant association of DRB1*1602-DQA1*0102-DQB1*0502 and HLA-DRB1*12-DQA1*0601-DQB1*0301 alleles and haplotypes with GD was recently reported in Korean but not in any Caucasian studies. Thus, DRB1*1602 allele and closely linked haplotype, DRB1*1602-DQA1*0102-DQB1*0502, might serve as a marker for genetic susceptibility to GD in Asian population.

Lymphoid tyrosine phosphatase (PTPN22/LYP) variant and Graves' disease in a Polish population: association and gene dose-dependent correlation with age of onset

OBJECTIVE

Susceptibility to Graves' disease (GD) is to a significant extent determined by genetic factors of which the best known are those associated with the HLA and the CTLA4 locus. Recently, two studies on British Caucasians reported that a single nucleotide polymorphism, 1858 C > T in PTPN22, encoding Arg620Trp in the lymphoid protein tyrosine phosphatase (LYP), which is a negative regulator of T-cell activation, increases the risk of GD. The purpose of our study was to investigate whether the PTPN22 'T' allele is associated with GD and/or its subsets, defined by clinical or genetic parameters, in a Polish population.

SUBJECTS AND DESIGN

A cohort of 290 patients and 310 controls was genotyped using a PCR-RFLP method. The distribution of PTPN22 alleles and genotypes among patients and controls was compared, and correlation was sought between PTPN22 'T' and sex, tobacco smoking status, family history of GD, age of disease onset, presence (and severity) of ophthalmopathy, and presence of the CTLA4 A49G or DRB1*03 alleles.

RESULTS

Association between GD and the PTPN22 'T' allele was confirmed (OR 1.7, P < 0.0008). Furthermore, a significant correlation between the PTPN22 genotype and the age of GD onset was demonstrated (r = -0.18, P = 0.0019). The PTPN22 'TT' and 'CC' genotypes defined groups characterized by more than twofold difference in median age of disease onset (20.8 years vs. 42 years, P < 0.003) whereas the 'CT' genotype was associated with an intermediate value (35 years). There were no statistically significant correlations with other analysed clinical or genetic parameters.

CONCLUSIONS

We replicated the association between Graves' disease and PTPN22 'T' reported in British Caucasians. We also found a gene dose-dependent effect of PTPN22 'T' on the age of onset of Graves' disease.

CT60 single nucleotide polymorphisms of the cytotoxic T-lymphocyte-associated antigen-4 gene region is associated with Graves' disease in an Italian population

Graves' disease (GD) is an autoimmune and polygenic disorder. Several studies have shown that human leukocyte antigen (HLA) class II and the cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) gene are involved in the genetic susceptibility. We performed a case control study on 150 patients with GD and 301 controls, matched for age and gender, to verify the association of three polymorphisms located in CTLA-4 region (A49G, [AT](n)-3'UTR, and CT60) and of HLA-DRB1 and DQB1 loci with the disease in an Italian population. The prevalence of patients with GD carrying the G allele of CT60 was significantly higher compared to control subjects (p = 0.02, odds ratio [OR] = 1.82). The allelic frequency of the G allele of CT60 was also significantly higher in patients with GD (p = 0.02). The G allele frequency of A49G in patients was significantly higher compared to control subjects (p = 0.04). The 280 allele phenotype frequency of (AT)(n)-3'UTR was also significantly higher in patients (p = 0.04). The G allele of A49G, the G allele of CT60, and the 280 allele of (AT)(n)-3'UTR microsatellite were significantly increased in patients with GD with thyroid-associated ophthalmopathy (TAO) compared to controls (p = 0.04, p = 0.03, and p = 0.02, respectively), however, we did not find any significant difference between TAO and non-TAO patients. We also found the HLA-DRB1*03 allele to be associated with GD; interestingly, the association of the CTLA-4 markers was independent from the HLA DRB1*03 status. These results highlight the role of the CTLA-4 locus, in addition to HLA, in the susceptibility to GD. Inside the CTLA-4 region, CT60 appears to be the most associated polymorphism to GD, however, further studies are needed to identify the etiologic variant.

Regression mapping of association between the human leukocyte antigen region and Graves disease

The human leukocyte antigen class II genes DRB1, DQB1, and DQA1 are associated with Graves disease (GD), but, because of strong linkage disequilibrium within this region, the primary etiological variant(s) remains unknown. In the present study, 871 patients with GD and 621 control subjects were genotyped at the DRB1, DQB1, and DQA1 loci. All three loci were associated with GD (P=1.45 x 10(-12), P=3.20 x 10(-5), and P=9.26 x 10(-12), respectively). Stepwise logistic-regression analysis showed that the association could be explained by either DRB1 or DQA1 but not by DQB1. To extend previous results, the amino acid sequence of the exon 2-encoded peptide-binding domain of DRB1 was predicted for each subject, and, by use of logistic regression, each position was analyzed for association with GD. Of 102 amino acids, 70 were uninformative; of the remaining 32 amino acids, 13 were associated with GD (P values ranged from 2.20 x 10(-4) to 1.2 x 10(-12)). The strongest association was at position beta 74. This analysis is consistent with the possibility that position beta 74 of exon 2 of the DRB1 molecule may have a specific and central role in autoantigen presentation by DRB1 to T lymphocytes. However, we cannot yet exclude a primary role for DQA1 or for other polymorphisms that affect DRB1 function or expression.

Graves' disease after interleukin-2 therapy in a patient with human immunodeficiency virus infection

Interleukin-2 (IL-2) is a cytokine that regulates the proliferation and differentiation of lymphocytes, and is currently used clinically in the treatment of assorted malignancies. Additionally, IL-2 is being actively investigated in clinical trials for treatment of human immunodeficiency virus (HIV) infection. Patients treated with IL-2 are susceptible to autoimmune thyroid disease (AITD), presenting as thyroiditis, which leads to either thyrotoxicosis or hypothyroidism, if not correctly and promptly identified and treated. IL-2-induced hypothyroidism can also sometimes follow a thyrotoxic phase. However, the development of Graves' disease (GD) in this clinical setting has not been reported to date. Here, we report the case of a 39-year-old HIV-infected man in whom GD developed after IL-2 therapy. We correlated the immunologic parameters pertinent to the patient's HIV infection status with clinical, hormonal, and serologic evidence of GD during its emergence. This revealed an association between peripheral blood cell numbers of specific lymphocyte subpopulations (CD4(+), CD3(+)CD25(+), and naïve T-cells) and serum levels of markers for AITD (free thyroxine [T(4)] and thyroid-stimulating immunoglobulin). Interestingly, no association was found between natural killer (NK) cell numbers and AITD markers. The immunopathogenesis of GD in this patient may be similar to that hypothesized for the GD that occurs in immune-reconstituted patients after combination antiretroviral therapy. From a practical standpoint, we propose that patients who have received or are receiving treatment with IL-2 who show signs of hyperthyroidism need to be carefully evaluated for GD.

Screening of SNPs at 18 positional candidate genes, located within the GD-1 locus on chromosome 14q23-q32, for susceptibility to Graves' disease: a TDT study

Graves' disease (GD) is a complex autoimmune thyroid disorder with a strong genetic component. Genome-wide screens resolved several susceptibility loci that contribute to the development of GD. One of the susceptibility loci (GD-1 locus) was mapped on chromosome 14q31. However, a susceptibility gene located within the GD-1 locus remains undefined. Here we screen eighteen single nucleotide polymorphisms (SNPs), each is situated at a corresponding positional candidate gene, located within the GD-1 susceptibility locus on chromosome 14q23-q32, for predisposition to GD using the transmission disequilibrium test in 126 simplex Russian families affected with GD. Among SNPs tested, a significant preferential transmission of the Ala allele (41 transmissions vs. 17 nontransmissions, corrected P=0.031) of the Thr92Ala SNP within the DIO2 gene, encoding type II iodothyronine deiodinase, from parents to affected children was found in a Russian family data set. The Thr92Ala SNP of the DIO2 gene and the D727E substitution of the thyrotropin receptor (TSHR) gene have been found to be in pair-wise linkage disequilibrium. The A92/E727 haplotype showed significant preferential transmission from parents to affected sibling (17 transmissions vs. 8 nontransmissions, P=0.039) in simplex families. This suggests that the Thr92Ala variant of the DIO2 gene is associated or may be in linkage disequilibrium with a functional DIO2 polymorphism which involves in the development of GD in a Russian population.

The thyroglobulin gene: the third locus for autoimmune thyroid disease or a false dawn?

Genetic studies have identified the HLA and CTLA4 regions as susceptibility loci for the development of common autoimmune thyroid diseases (AITDs), including Graves' disease and autoimmune hypothyroidism. Despite numerous studies, the identification of a third locus has remained elusive. Genetic-linkage studies have implicated chromosome 8q24 as a susceptibility locus for AITD. The gene encoding thyroglobulin (Tg), which encodes a major thyroid autoantigen, maps to this region, and a recent study has reported the association of several exonic single-nucleotide polymorphisms (SNPs) with disease. Although these preliminary data are potentially exciting, caution needs to be exercised, and replication of the data sought before Tg can be designated as the third locus for AITD.

Unravelling the genetic complexity of autoimmune thyroid disease: HLA, CTLA-4 and beyond

The autoimmune thyroid diseases (AITDs) including Graves' disease (GD) and autoimmune hypothyroidism (AIH) are the commonest of the autoimmune conditions affecting 2-5% of the western population. Twin studies have clearly demonstrated that AITDs are caused by a combination of both environmental and genetic factors. Association of the HLA class II region with AITD has been documented for over 20 years now, but the primary aetiological variant in this region remains unknown. More recently the CTLA-4 gene region has been identified as the second locus conferring susceptibility to AITD. In contrast to HLA, a polymorphism of the CTLA-4 gene, which encodes an important negative regulator of the immune system, has been identified as a candidate for a primary determinant for AITD. A large number of candidate gene and genome wide linkage studies have been involved in the search for the elusive 'third' locus. The thyroglobulin (Tg) gene in humans maps to chromosome 8q, which has been linked in family studies to AITD. A number of association studies in humans and the mouse model for AITD are beginning to implicate the Tg gene although convincing evidence for a primary causative role is still needed. The establishment of large DNA disease resources along with more detailed genetic maps and the development of faster, more effective, high throughput genotyping and sequencing methods, provides some sense of optimism that novel loci will be identified in the near future and the complex aetiology of AITD will be further unraveled.

Polymorphism in the transmembrane region of the major histocompatibility complex class I chain-related gene A: association of five GCT repetitions with Graves' disease in children

Graves' disease is an autoimmune disease involving a complex interplay of multiple genetic and environmental influences. An association between the disorder and the major histocompatibility complex (MHC; human leukocyte antigen [HLA]) region has long been reported. The major histocompatibility complex class I chain-related gene A (MICA) has a triplet repeat polymorphism in the transmembrane region consisting of six alleles. For this study, the polymorphism in question was analyzed for 129 unrelated children with Graves' disease (97 girls and 32 boys, 10.0 +/- 3.0 years of age) and 396 randomly selected, unrelated subjects (205 females, 191 males, 8.4 +/- 13.5 years of age). The frequencies of genotype A5/A5 and A5/A5.1 were significantly higher in patients than in controls (relative risk [RR] = 2.49, 95% confidence interval [CI] 1.52-4.10, p = 0.00024, pc = 0.0035 and RR = 2.13, 95% CI 1.31-3.47, p = 0.0020, pc = 0.030; respectively). The frequency of genotype A5.1/A5.1 was significantly lower in patients than in controls (RR = 0.09, 95% CI 0.01-0.66, p = 0.0030, pc = 0.044). Allele frequency for allele A5 was significantly higher for children with Graves' disease compared to controls (RR = 2.12; 95% CI = 1.59-2.82; p = 1.9 x 10(-7); pc = 9.5 x 10(-7)). This study demonstrates that MICA allele A5 confers the risk for Graves' disease.

Association study of autoimmune thyroid disease at 5q23-q33 in Japanese patients

As part of a genome scan to locate familial Graves' disease (GD) and Hashimoto's thyroiditis (HT) genes, an autoimmune thyroid disease (AITD) susceptibility locus has recently been identified at 5q31-q33 in a Japanese population. We performed an association study using six microsatellite markers located at this locus in a set of 440 unrelated Japanese AITD patients and 218 Japanese controls. We found significant allelic association between AITD and three markers located in 5q23-q33. GD demonstrated significant associations with two of these markers, while HT did not show significant associations with any markers. Further, when patients with GD were stratified according to clinical manifestations, the association was significantly different from the other subgroup of each category. These findings suggest the presence of susceptible genes of AITD, especially distinct subgroups of GD, in or near 5q23-q33.

Prevalence and clinico-epidemiology of familial Graves' disease in Japan based on nationwide epidemiologic survey in 2001

A nationwide epidemiologic survey of familial Graves' disease (GD) was conducted in 2001. "Familial GD" was defined as a patient who had at least one Graves' patient within the proband's first-degree relatives. The primary survey was performed for estimating the prevalence of patients among a random selection of 2367 departments/hospitals of internal medicine, endocrinology, thyroidology and pediatrics. Of those receiving the primary questionnaire, 1361 (57.5%) responded, and 902 familial GD patients who visited them in 2000 were reported. The total number of patients was estimated to be 2850 (95% confidence intervals: 2100-3600). Based on the nationwide survey concerning the prevalence of hyperthyroidism in 1999, 2.1-3.1% of hyperthyroidism appeared to be familial GD and the relative risk of familial GD was roughly estimated to be 19-42. Subsequently, a second survey was carried out for obtaining the clinicoepidemiologic features of those patients. Of 902 patients, 487 (54%) were reported. No significant differences between familial and non-familial GD were found in age and sex distributions, clinical features or laboratory findings. Familial GD possessed the highest association with Hashimoto's thyroiditis, approximately 8% within the first-degree relatives, suggesting a shared genetic predisposition. These findings confirm the familial clustering of GD in the Japanese population, indicating the importance of environmental factors, genetic factors or both in the development of the disease.

The genetics of autoimmune endocrine disease

The common autoimmune endocrinopathies result from an interaction between environmental factors and genetic predisposition. Several chromosomal gene regions have been shown to contribute to more than one disease, supporting the clinical observation that the autoimmune endocrine diseases cluster within individuals and families. Genetic studies have implicated the major histocompatability complex (MHC)-human leucocyte antigen (HLA) genes on chromosome 6p21, although this chromosomal region does not explain all of the genetic contribution to the various disorders. Non-MHC-HLA genes, including disease-specific loci, are beginning to be identified and the publication of the draft sequence of the human genome will undoubtedly expediate future discoveries. Combined with the establishment of large cohorts of subjects with disease and the development of technology capable of performing high-throughput genotyping, genetic studies are likely to impact on the future treatment and prevention of the common autoimmune endocrine diseases.

Development of Graves' disease in a patient under immunosuppressive therapy after liver transplantation

Susceptibility to Graves' disease (GD) is determined by multiple environmental and genetic factors, which are not fully understood. Because of the autoimmune etiology of the disease, recent reports describing the development of GD during long-term immunosuppressive treatment seem quite surprising. We report a second case of GD in a 17-yr old patient, treated with cyclosporin A and prednisone, after liver transplantation. The development of GD despite adequate immunosuppressive therapy may suggest that this patient had a genetic predisposition to autoimmunity and severe immunoregulatory defects. We analyzed the HLA-DRB1 alleles and cytotoxic T lymphocyte associated antigen-4 (CTLA-4) gene polymorphism (A/G) at position 49 in exon 1. The patient had the HLA-DRB1*03 allele which is known to confer susceptibility to GD. Further studies are necessary to identify genes that may predispose patients specifically to GD during immunosuppressive therapies.

Inflammatory thyroid disorders

Inflammatory thyroid disorders encompass a broad spectrum of diseases that are generally self-limited, and relatively easy to diagnose and manage. Autoimmune subtypes are by far the most commonly encountered diagnoses and create the most confusion because of simultaneous overlap and the potential for interconversion among the subtypes. The otolaryngologist will frequently see these disorders and provide valued consultative care and surgical intervention as needed.

Genome-wide linkage analysis of families with obsessive-compulsive disorder ascertained through pediatric probands

The goal of this study was to identify chromosomal regions likely to contain susceptibility alleles for early-onset obsessive-compulsive disorder (OCD). A genome scan was done in 56 individuals from seven families ascertained through pediatric OCD probands; 27 of the 56 subjects had a lifetime diagnosis of definite OCD. Denser mapping of regions on chromosomes 2, 9, and 16 was subsequently done with those subjects and ten additional subjects from the largest family in the study. Direct interviews were completed with 65 of the 66 genotyped individuals. Relatives were interviewed blind to proband status. Of the 65 interviewed individuals, 32 had a lifetime diagnosis of definite OCD. Three of the seven probands had a history of Tourette disorder. Two of the 25 relatives with OCD had a tic history, whereas none of the 33 relatives without OCD had tics. The genome scan consisted of 349 microsatellite markers with an average between-marker distance of 11.3 centiMorgan (cM). Fine mapping was done with 24 additional markers at an average spacing of 1.6 cM. Parametric and nonparametric linkage analyses were conducted using GENEHUNTER(+). The maximum multipoint LOD score with a dominant model was 2.25 on 9p. However, with fine mapping and additional subjects, that LOD score decreased to 1.97. The maximum multipoint nonparametric LOD* score was 1.73 on 19q. The maximum multipoint LOD score with a recessive model was 1.40 on 6p. The results provide suggestive evidence for linkage on 9p and identify regions requiring further study with much larger samples.

Polymorphism of the CTLA-4 gene is associated with autoimmune hypothyroidism in the United Kingdom

The cytotoxic T-lymphocyte-associated-4 (CTLA-4) molecule plays an important role in immune regulation by downregulating activation of T cells by antigen-presenting cells. Polymorphisms of the CTLA-4 gene have been shown to be associated with susceptibility to a number of autoimmune diseases. Some, but not all, studies suggest association between the CTLA-4 gene and autoimmune hypothyroidism. The aim of this study was to determine whether allelic association was present between the A-G single nucleotide polymorphism (SNP) at position 49 in exon 1 of the CTLA-4 gene and autoimmune hypothyroidism. The study was performed in 158 patients with autoimmune hypothyroidism and 384 control subjects. All subjects were white Caucasians from the United Kingdom. Genotyping was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using the restriction enzyme Bbv1. There was a significant excess of the G allele in patients with autoimmune hypothyroidism compared with controls (43% vs. 32% respectively; chi2 = 10.7, p = 0.001; odds ratio 1.57). The GG and the AG genotypes were found to be more frequent in patients with autoimmune hypothyroidism than controls (17% vs. 8.8% and 50% vs. 46% respectively; chi2 = 11.7, p = 0.003). These results suggest that the CTLA-4 gene region on chromosome 2q33 is a susceptibility locus for autoimmune hypothyroidism in the United Kingdom.

Beta-cell, thyroid, gastric, adrenal and coeliac autoimmunity and HLA-DQ types in type 1 diabetes

The autoimmune attack in type 1 diabetes is not only targeted to beta cells. We assessed the prevalence of thyroid peroxidase (aTPO), parietal cell (PCA), antiadrenal (AAA) and endomysial antibodies (EmA-IgA), and of overt autoimmune disease in type 1 diabetes, in relation to gender, age, duration of disease, age at onset, beta-cell antibody status (ICA, GADA, IA2A) and HLA-DQ type. Sera from 399 type 1 diabetic patients (M/F: 188/211; mean age: 26 +/- 16 years; duration: 9 +/- 8 years) were tested for ICA, PCA, AAA and EmA-IgA by indirect immunofluorescence, and for IA2A (tyrosine phosphatase antibodies), GADA (glutamic acid decarboxylase-65 antibodies) and aTPO by radiobinding assays. The prevalence rates were: GADA 70%; IA2A, 44%; ICA, 39%; aTPO, 22%; PCA, 18%; EmA-IgA, 2%; and AAA, 1%. aTPO status was determined by female gender (beta = - 1.15, P = 0.002), age (beta = 0.02, P = 0.01) and GADA + (beta = 1.06, P = 0.02), but not by HLA-DQ type or IA2A status. Dysthyroidism (P < 0.0001) was more frequent in aTPO + subjects. PCA status was determined by age (beta = 0.03, P = 0.002). We also observed an association between PCA + and GADA + (OR = 1.9, P = 0.049), aTPO + (OR = 1.9, P = 0.04) and HLA DQA1*0501-DQB1*0301 status (OR = 2.4, P = 0.045). Iron deficiency anaemia (OR = 3.0, P = 0.003) and pernicious anaemia (OR = 40, P < 0.0001) were more frequent in PCA + subjects. EmA-IgA + was linked to HLA DQA1*0501-DQB1*0201 + (OR = 7.5, P = 0.039), and coeliac disease was found in three patients. No patient had Addison's disease. In conclusion, GADA but not IA2A indicate the presence of thyrogastric autoimmunity in type 1 diabetes. aTPO have a female preponderance, PCA are weakly associated with HLA DQA1*0501-DQB1*0301 and EmA-IgA + with HLA DQA1*0501-DQB1*0201.

Validity of self-reported hyperthyroidism and hypothyroidism: comparison of self-reported questionnaire data with medical record review

Studies that aim at identifying genes or environmental factors contributing to the development of autoimmune thyroid disease (AITD) demand that several hundred patients and control subjects be assessed. In these large studies, the laboratory methodology is often described in detail whereas little attention is given to an accurate description of the study population. Usually, a diagnosis of AITD in the control group is based on self-reported disease status. Although such studies have been criticized for diagnostic inaccuracy, no study has evaluated the validity of self-reported hyperthyroidism and hypothyroidism in detail. We have assessed the validity of self-reported hyperthyroidism and hypothyroidism in 401 twin pairs from among 6,628 same gender pairs, ages 18-41 years who participated in a nationwide questionnaire survey in 1994. The self-reported questionnaire data were compared with information from medical records and the 1/kappa coefficient, sensitivity, and specificity were determined. Overall, there was only a slight to fair agreement between the self-reported questionnaire data and medical record data as shown by kappa values of 0.18, 0.21, and 0.26 for hyperthyroidism and hypothyroidism as a group, hyperthyroidism and hypothyroidism, respectively. For both hyperthyroidism and hypothyroidism, the sensitivity of the self-reported diagnosis was 0.98, whereas the specificity was 0.57 and 0.67 for self-reported hyperthyroidism and hypothyroidism, respectively. In conclusion, the validity of self-reported hyperthyroidism and hypothyroidism is unsatisfactorily low. However, by combining self-reports with valid retrospective data on diagnostic findings it can be used as a sampling method in large epidemiological or genetic studies.