HLA and Graves' disease in Koreans

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.

Case Report: A Rare Case of Coexisting of Autoimmune Polyglandular Syndrome Type 3 and Isolated Gonadotropin-Releasing Hormone Deficiency

APS (autoimmune polyglandular syndrome) is defined as the coexistence of at least two kinds of endocrine autoimmune diseases. APS type 3 comprises autoimmune thyroid diseases and other autoimmune diseases but does not involve autoimmune Addison’s disease. So far, APS-3 combined with isolated gonadotropin-releasing hormone (GnRH) reduction caused by the suspected autoimmune hypothalamic disease has not been reported. We recently received a 43-year-old woman with a one-year history of Graves’ disease (GD) and a four-month history of type 1 diabetes presented with hyperthyroidism and hyperglycemia. After the GnRH stimulation test, she was diagnosed with secondary amenorrhea attributed to suspected autoimmune Hypothalamitis and APS type 3 associated with Graves’ disease and Latent Autoimmune Diabetes (LADA). According to this case, the hypothalamus cannot be spared from the general autoimmune process. It is recommended to carry out the GnRH stimulation test when encountering APS patients combined with secondary amenorrhea.

GPR174 and ITM2A Gene Polymorphisms rs3827440 and rs5912838 on the X chromosome in Korean Children with Autoimmune Thyroid Disease

(1) Background: Autoimmune thyroid diseases (AITDs) are female predominant and much attention has been focused on G protein-coupled receptor 174 (GPR174) and integral membrane protein 2A (ITM2A) on the X chromosome as Grave's disease (GD) susceptible locus. (2) Methods: We genotyped four single nucleotide polymorphisms (SNPs), rs3810712, rs3810711, rs3827440, and rs5912838, of GPR174 and ITM2A in 115 Korean children with AITD (M = 25 and F = 90; GD = 74 (14.7 ± 3.6 years), HD = 41 (13.4 ± 3.2 years); GD-thyroid-associated ophthalmopathy (TAO) = 40, GD-non-TAO=34) and 204 healthy Korean individuals (M = 104 and F = 100). The data were analyzed by sex-stratified or combined. (3) Results: Three SNPs, rs3810712, rs3810711 and rs3827440, were found to be in perfect linkage disequilibrium (D' = 1, r² = 1). In AITD, HD, GD, GD-TAO, and GD-non-TAO patients, rs3827440 TT/T and rs5912838 AA/A were susceptible and rs3827440 CC/C and rs5912838 CC/C were protective genotypes. When analyzed by sex, rs3827440 TT and rs5912838 AA were susceptible and rs3827440 CC and rs5912838 CC were protective genotypes in female AITD, GD, GD-TAO, and GD-non-TAO subjects. In male AITD patients, rs3827440 T and rs5912838 A were susceptible and rs3827440 C and rs5912838 C were protective genotypes. (4) Conclusions: Polymorphisms in GPR174 and ITM2A genes on the X chromosome might be associated with AITD in Korean children.

Association of Polymorphisms in Toll-Like Receptors 4 and 9 with Autoimmune Thyroid Disease in Korean Pediatric Patients

BACKGROUND

Toll-like receptors (TLRs) have been suggested to be associated with the development of AITD.

METHODS

Fifteen single-nucleotide polymorphisms in 7 TLR genes were analyzed in 104 Korean children (girls = 86, boys = 18) with AITD (Hashimoto disease (HD) = 44, Graves' disease (GD) = 60, thyroid-associated ophthalmopathy (TAO) = 29, and non-TAO = 31) with 183 controls.

RESULTS

GD showed higher frequencies of the TLR4 rs1927911 C allele than control. TAO showed a lower frequency of the TLR4 rs1927911 CT genotype and non-TAO showed a higher frequency of the TLR4 rs1927911 CC genotype than control. The frequency of the TLR9 rs187084 CC genotype in TAO was higher than that in non-TAO. GD females showed a higher frequency of the TLR4 rs10759932 T allele, rs1927911 CC genotype, and the rs1927911 C allele than controls. GD males showed a higher frequency of the TLR4 rs10759932 CC genotype and rs1927911 TT genotype and lower frequency of the rs1927911 CT genotype than control. The frequency of the TLR4 rs10759932 CC genotype, C allele and rs1927911 TT genotype, and T allele in a GD female were lower than in a GD male.

CONCLUSIONS

Our results suggest that TLR4 and 9 polymorphisms might contribute to the pathogenesis of GD and TAO.

Comprehensive analysis of cytokine gene polymorphisms defines the association of IL-12 gene with ophthalmopthy in Korean children with autoimmune thyroid disease

In early onset autoimmune thyroid disease (AITD) showing a strong genetic tendency, cytokines have been suggested to play a critical role in the development of AITD. To directly compare the influences of several cytokine gene polymorphisms, 25 single nucleotide polymorphisms (SNPs) in 17 cytokine genes were analyzed on 104 Korean children with AITD [Hashimoto's disease (HD) = 44, Graves' disease (GD) = 60 (thyroid-associated ophthalmopathy (TAO) = 29, non-TAO = 31)] and 192 controls. Compared with healthy controls, any significant association with polymorphisms of cytokine genes was not found in HD and GD. Among GD patients, non-TAO group only showed significant associations with IL-12 C allele (rs3212227: A > C) (76.6% vs. 51.6%, OR = 0.3 [0.15-0.71], Pc = 0.007). Particularly, the frequency of IL-12C allele was significantly lower in the non-TAO group than in the TAO group (82.8% vs. 51.6%, Pc = 0.018). Our comprehensive analysis of cytokine gene polymorphisms suggests that IL-12 gene may play impact on specific pathogenesis of ophthalmopathy in Korean children with AITD.

Association of Toll-like receptor 10 polymorphisms with autoimmune thyroid disease in Korean children

BACKGROUND

The Toll-like receptors (TLRs) are germline-encoded receptors that play an essential role in initiating the immune response against pathogens. In this study, we assess the association of TLR polymorphism with autoimmune thyroid disease (AITD) in Korean children.

METHODS

We investigated three polymorphisms in the TLR10 gene (rs4129009, rs11096956, and rs10004195) in 85 Korean AITD patients (Graves' disease, [GD]=50, Hashimoto's disease [HD]=35; thyroid-associated ophthalmopathy [TAO]=23, non-TAO=62; male=16, female=69; mean age=13.4±3.1 years) and 279 healthy control subjects.

RESULTS

In patients with AITD, the frequencies of the TLR10 rs4129009 A allele (odds raio [OR]=3.9, corrected p=0.04) and rs10004195 T allele (OR=2.8, corrected p=0.02) were higher than in the healthy controls, whereas the TLR10 rs4129009 GG genotype (OR=0.3, corrected p=0.04) and rs10004195 AA genotype (OR=0.4, corrected p=0.02) showed lower frequencies. The TLR10 rs11096956 did not show any significant association. These significant associations were also found in the non-thyroid-associated ophthalmopathy (TAO) group, but not in the TAO group. The haplotype (AGT) frequency of TLR10 rs4129009, rs11096956, and rs10004195 was higher in the AITD group than in healthy controls (OR=2.1, corrected p=0.03).

CONCLUSIONS

Our results suggest that TLR10 polymorphisms may contribute to the pathogenesis of AITD.

Ethnic differences in the clinical presentation of Graves' ophthalmopathy

Ethnic differences in a number of eye conditions have been described. The literature on ethnic differences in Graves' ophthalmopathy (GO) is limited. There is some evidence to suggest Asian patients with GO may manifest milder phenotypic features of GO, with less proptosis and evidence of extraocular muscle involvement and restriction. The reasons for these differences are likely to be multifactorial and include orbital and lid anatomy, genetic background and autoimmune responses including TSH -receptor antibodies. These differences should be kept in mind when evaluating and managing patients with GO.

Comprehensive genotyping in two homogeneous Graves' disease samples reveals major and novel HLA association alleles

BACKGROUND

Graves' disease (GD) is the leading cause of hyperthyroidism and thyroid eye disease inherited as a complex trait. Although geoepidemiology studies showed relatively higher prevalence of GD in Asians than in Caucasians, previous genetic studies were contradictory concerning whether and/or which human leukocyte antigen (HLA) alleles are associated with GD in Asians.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted a case-control association study (499 unrelated GD cases and 504 controls) and a replication in an independent family sample (419 GD individuals and their 282 relatives in 165 families). To minimize genetic and phenotypic heterogeneity, we included only ethnic Chinese Han population in Taiwan and excluded subjects with hypothyroidism. We performed direct and comprehensive genotyping of six classical HLA loci (HLA-A, -B, -C, -DPB1, -DQB1 and -DRB1) to 4-digit resolution. Combining the data of two sample populations, we found that B*46:01 (odds ratio under dominant model [OR]  = 1.33, Bonferroni corrected combined P [P(Bc)]  = 1.17 x 10⁻²), DPB1*05:01 (OR  = 2.34, P(Bc) = 2.58 x 10⁻¹⁰), DQB1*03:02 (OR  = 0.62, P(Bc)  = 1.97 x 10⁻²), DRB1*15:01 (OR  = 1.68, P(Bc) = 1.22 x 10⁻²) and DRB1*16:02 (OR  = 2.63, P(Bc)  = 1.46 x 10⁻⁵) were associated with GD. HLA-DPB1*05:01 is the major gene of GD in our population and singly accounts for 48.4% of population-attributable risk.

CONCLUSIONS/SIGNIFICANCE

These GD-associated alleles we identified in ethnic Chinese Hans, and those identified in other Asian studies, are totally distinct from the known associated alleles in Caucasians. Identification of population-specific association alleles is the critical first step for individualized medicine. Furthermore, comparison between different susceptibility/protective alleles across populations could facilitate generation of novel hypothesis about GD pathophysiology and indicate a new direction for future investigation.

Linkage of Graves' disease to the human leucocyte antigen region in the Chinese-Han population in Taiwan

OBJECTIVE

To investigate whether markers in the candidate chromosome regions, including the human leucocyte antigen (HLA) region, are linked to Graves' disease (GD).

DESIGN

A familial linkage study with a candidate region approach.

PATIENTS

A total of 536 individuals in 122 multiplex Chinese-Han families with a GD proband and at least one other affected sibling, resulting in 270 affected sib-pairs. Subjects with a family history of noniatrogenic hypothyroidism or Hashimoto's thyroiditis were excluded.

MEASUREMENTS

We genotyped eight short tandem repeat polymorphism (STRP) markers in a 13.7 cM region covering the HLA region on chromosome 6p21 and 26 STRPs in four other candidate regions previously reported in the literature.

RESULTS

Multipoint nonparametric linkage (NPL) analysis showed significant linkage to the HLA region [the marker UniSTS:239159, nonparametric log of odds (LOD) score 3.44, P = 0.00003; NPL Z-score 4.1, P = 0.00002] from 270 affected sib-pairs. The 1-LOD support interval comprised the whole HLA region (ca. 4 Mb). By contrast, the maximal NPL Z-scores of the markers of the other candidate regions (2q33, 5q31, 7q22 and 14q31) previously reported were all less than 1.0.

CONCLUSIONS

Our results provide strong support for linkage of GD to the HLA region. Further dissection of this region to identify the candidate gene for GD is warranted in our population.

Association of HLA-DR and -DQ Genes with Graves Disease in Koreans

Graves disease (GD) is an autoimmune thyroid disease and is associated with human leukocyte antigen (HLA)-DR3 and DQA1*0501 in Caucasians. However, the association of HLA with GD is less clear-cut in East Asian populations. We analyzed HLA-DRB1 and -DQB1 associations with GD in 198 Korean patients compared with 200 healthy controls. HLA-DRB1*0803 (27.8% vs. 14.5% in controls, OR = 2.27, corrected p [p(c)] = 0.03) and *1602 (5.1% vs. 0%, OR = 22.34, p(c) = 0.03) alleles and closely linked haplotypes, DRB1*0803-DQB1*0601 and DRB1*1602-DQB1*0502, conferred susceptibility to GD in Koreans. Weak association of DRB1*0301 with GD susceptibility was observed in male patients only (12.5% vs. 3.5%, OR = 3.57, p < 0.05). HLA-DRB1*0101, *0701, *1202, and *1302 alleles were weakly associated with resistance to the disease (OR < 0.5, p < 0.05). Some HLA alleles were weakly associated with clinical characteristics in GD patients. Patients with DRB1*1301-DQB1*0603 developed their diseases in younger ages and were more frequently associated with larger goiter (p < 0.05). Although HLA class II alleles associated with GD in Koreans were different from those in Caucasians, some associations are shared, such as association of DRB1*0301 in male patients and protective effect of DRB1*0701 to GD susceptibility.

The contribution of immune regulatory and thyroid specific genes to the etiology of Graves' and Hashimoto's diseases

The autoimmune thyroid diseases (AITD) are complex diseases which are caused by an interaction between susceptibility genes and environmental triggers. Genetic susceptibility in combination with external factors (e.g. dietary iodine) are believed to initiate the autoimmune response to thyroid antigens. Abundant epidemiological data, including family and twin studies, point to a strong genetic influence on the development of AITD. Various techniques have been employed to identify the genes contributing to the etiology of AITD, including candidate gene analysis and whole genome screening. These studies have enabled the identification of several loci (genetic regions) that are linked with AITD, and in some of these loci putative AITD susceptibility genes have been identified. Some of these genes/loci are unique to Graves' disease (GD) and Hashimoto's thyroiditis (HT) and some are common to both diseases, indicating that there is a shared genetic susceptibility to GD and HT. The putative GD and HT susceptibility genes include both immune modifying genes (e.g. HLA, CTLA-4) and thyroid specific genes (e.g. TSHR, Tg). Most likely these loci interact and their interactions may influence disease phenotype and severity.

Searching for the autoimmune thyroid disease susceptibility genes: from gene mapping to gene function

The autoimmune thyroid diseases (AITD) are complex diseases that are caused by an interaction between susceptibility genes and environmental triggers. Genetic susceptibility, in combination with external factors (e.g., dietary iodine), is believed to initiate the autoimmune response to thyroid antigens. Abundant epidemiological data, including family and twin studies, point to a strong genetic influence on the development of AITD. Various techniques have been used to identify the genes contributing to the etiology of AITD, including candidate gene analysis and whole genome screening. These studies have enabled the identification of several loci (genetic regions) that are linked with AITD, and in some of these loci putative AITD susceptibility genes have been identified. Some of these genes/loci are unique to Graves' disease (GD) and Hashimoto's thyroiditis (HT), and some are common to both diseases, indicating that there is a shared genetic susceptibility to GD and HT. The putative GD and HT susceptibility genes include both immune modifying genes (e.g., human leukocyte antigen, cytotoxic T lymphocyte antigen-4) and thyroid-specific genes (e.g., TSH receptor, thyroglobulin). Most likely these loci interact, and their interactions may influence disease phenotype and severity. It is hoped that in the near future additional AITD susceptibility genes will be identified and the mechanisms by which they induce AITD will be unraveled.

The association of HLA -A, -B, and -DRB1 genotypes with Graves' disease in Taiwanese people

Graves' disease has been associated with different human leukocyte antigen (HLA) genes in different races. To evaluate the association of HLA type in Taiwanese with Graves' disease, the HLA-A, -B, and -DRB1 alleles in a total of 236 Taiwanese adults with Graves' disease and 533 racially matched normal control subjects were examined using the PCR-SSOP (sequence specific oligonucleotide probe) technique. The prevalence of HLA-A*0207, -B*2704, -B*4601, and -DRB1*0901 among patients with Graves' disease was found to be increased, with odds ratios (OR) of 2.21, 3.82, 1.76 and 1.62, respectively. However, after correction for multiple comparisons, the relative risk of HLA-A*0207 susceptibility to Graves' disease remained statistically significant and the haplotype HLA-A*3303 -B*5801 -DRB1*0301 had a significantly protective effect. None of the other 2- or 3-locus haplotypes showed any significantly increased risk. Although HLA-DRB1*1405 showed an increased relative risk in patients with GO (Graves' opthalmopathy) (OR 4.61) when compared with patients without GO, the relative risk after adjusting for the number of comparisons was not significant. Taiwanese patients with Graves' disease have HLA-associated susceptibility genes which are similar to those found in Chinese patients in Hong Kong and Singapore. However, the finding in this study of a higher frequency of HLA-A*0207 in Taiwanese with Graves' disease has not been documented in any other ethnic group.

The genetic susceptibility to Graves' disease

Graves' disease (GD) develops as a result of a complex interaction between genetic susceptibility genes and likely environmental factors. Most epidemiological data support an important genetic contribution to the development of GD. The concordance rate of GD in monozygotic twins is 30-60% and in dizygotic twins 3-9%, and thyroid autoantibodies have been reported in up to 50% of the siblings of patients with GD. For many years now, HLA studies have consistently shown an increased frequency of HLA-DR3 in Caucasian patients with GD; but with only a risk ratio of 3-5. However, recent advances in human genome mapping techniques have enabled the study of many other candidate genes. Of these additional, non-HLA genes, only CTLA-4 has been consistently found to be associated with GD. Using a linkage based approach which only detects highly significant susceptibility genes we have recently reported preliminary results which demonstrated that a marker located approximately 25 cM from the TSH receptor gene on chromosome 14q31 is linked to GD and in the same vicinity as the IDDM-11 locus. Such results, if confirmed, may signal the presence of a gene family related to endocrine autoimmunity on chromosome 14q31.

An HLA-DRB alpha-helix motif shared by DR11 and DR8 alleles is implicated in the pluriallelic restriction of peptide-specific T-cell lines

The T-cell recognition of HLA-DR-peptide complexes is generally restricted by the polymorphism of the DRB molecules but pluriallelic restriction has been described. The molecular basis of restriction and promiscuity of such peptide-specific responses is poorly understood. We isolated a panel of T-cell lines specific for the tetanus toxin peptide p2 (TT830-843) exhibiting pluriallelic restriction by DR11 and DR8 alleles. Fine restriction specificity of the T-cell lines was examined in functional assays against DR oligotyped APCs expressing different variants of DR11 and DR8 alleles. Our results show that (a) polymorphisms between serologically related alleles are relevant in terms of restriction of the peptide-specific T-cell response; in some instances, a single amino acid substitution can determine the restriction of a T-cell line; (b) different patterns of restriction are not the result of specific differences in DR-p2 binding as p2 peptide binds to all DR11 and DR8 alleles tested (DRB1* 1101, -1102, -1103, -1104, 110X, -0801, -0802, -0803, and -0806); and (c) pluriallelic restriction of the peptide-specific T-cell response correlates with the presence of a DRB1 alpha-helix motif (67-71-86) shared by some DR11 and DR8 alleles. Possible implications of pluriallelic restriction of peptide-specific T-cell response in autoimmune disorders associated with DR11 and DR8 are discussed.

HLA-DR antigen expression on the thyrocytes of Graves' disease patients

To confirm the expression of HLA-DR antigen on the thyrocytes of Graves’ disease patients and study the relation between the degree of DR antigen expression and clinical or laboratory indices, double immunofluorescence and immunoenzymatic staining were performed on frozen thyroid sections. DR antigen was expressed on the thyrocytes of 8 of 11 patients with Graves’ disease (73%) but not found on the thyrocytes from 6 normal controls. The degree of DR antigen expression had no apparent correlation with the age, duration of the disease, activity of TBII, titers of antimicrosomal and antithyroglobulin antibody. There was no apparent spatial or quantitative relation between lymphoid follicle formation and the DR antigen expression on the thyroid follicles. But DR antigen tended to be expressed on the thyroid tissue with interstitial, lymphocyte infiltration. In conclusion, DR antigen was expressed on the thyrocytes of Graves’ disease patients but the clinical and immunological significance remains to be clarified.