Association of HLA-DPB1*0501 with early-onset Graves' disease in Japanese

Neoself Antigens Presented on MHC Class II Molecules in Autoimmune Diseases

Major histocompatibility complex (MHC) class II molecules play a crucial role in immunity by presenting peptide antigens to helper T cells. Immune cells are generally tolerant to self-antigens. However, when self-tolerance is broken, immune cells attack normal tissues or cells, leading to the development of autoimmune diseases. Genome-wide association studies have shown that MHC class II is the gene most strongly associated with the risk of most autoimmune diseases. When misfolded self-antigens, called neoself antigens, are associated with MHC class II molecules in the endoplasmic reticulum, they are transported by the MHC class II molecules to the cell surface without being processed into peptides. Moreover, neoself antigens that are complexed with MHC class II molecules of autoimmune disease risk alleles exhibit distinct antigenicities compared to normal self-antigens, making them the primary targets of autoantibodies in various autoimmune diseases. Elucidation of the immunological functions of neoself antigens presented on MHC class II molecules is crucial for understanding the mechanism of autoimmune diseases.

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.

Abrogation of self-tolerance by misfolded self-antigens complexed with MHC class II molecules

Specific MHC class II alleles are strongly associated with susceptibility to various autoimmune diseases. Although the primary function of MHC class II molecules is to present peptides to helper T cells, MHC class II molecules also function like a chaperone to transport misfolded intracellular proteins to the cell surface. In this study, we found that autoantibodies in patients with Graves' disease preferentially recognize thyroid-stimulating hormone receptor (TSHR) complexed with MHC class II molecules of Graves' disease risk alleles, suggesting that the aberrant TSHR transported by MHC class II molecules is the target of autoantibodies produced in Graves' disease. Mice injected with cells expressing mouse TSHR complexed with MHC class II molecules, but not TSHR alone, produced anti-TSHR autoantibodies. These findings suggested that aberrant self-antigens transported by MHC class II molecules exhibit antigenic properties that differ from normal self-antigens and abrogate self-tolerance, providing a novel mechanism for autoimmunity.

Neuromyelitis optica spectrum disorders

The disease concept of Neuromyelitis Optica Spectrum Disorders(NMOSD) has undergone a significant change over the last two decades including the detection of Myelin Oligodendrocyte Glycoprotein(MOG) antibody in patients who are seronegative for aquaporin-4 antibody. Aquaporin-4 antibody positive NMOSD is now regarded as an immune astrocytopathy. Conversely, MOG antibody associated disease is known to target myelin rather than astrocytes, leading to an NMOSD syndrome with distinct clinical and radiological features. Incorporation of clinical features like area postrema syndrome, brainstem syndrome, diencephalic syndrome and cortical manifestations as core clinical characteristics into the revised diagnostic criteria has widened the clinical spectrum of NMOSD. With the development of these criteria, it is possible to make the diagnosis at an earlier stage so that effective immunosuppression can be instituted promptly for a better long-term prognosis. Newer therapeutic agents have been introduced for aquaporin-4 seropositive NMOSD disease; however, challenges remain in treating seronegative disease because of limited treatment options.

HLA alleles, especially amino-acid signatures of HLA-DPB1, might contribute to the molecular pathogenesis of early-onset autoimmune thyroid disease

The major histocompatibility complex region has been suggested to play an important role in the development of autoimmune thyroid disease (AITD). In this study, we investigated the associations of human leukocyte antigen (HLA) alleles and amino acid variants of HLA with early-onset AITD. HLA class I and class II genes were analyzed in 116 Korean children with AITDs (Graves’ disease [GD]: 71, Hashimoto’s disease [HD]: 45) and 142 healthy controls. HLA-B*46:01 (OR = 3.96, Pc = 0.008), -C*01:02 (OR = 2.51 Pc = 0.04), -DPB1*02:02 (OR = 3.99, Pc = 0.04), and -DPB1*05:01 (OR = 4.6, Pc = 0.003) were significantly associated with GD, and HLA-A*02:07 (OR = 4.68, Pc = 0.045) and -DPB1*02:02 (OR = 6.57, Pc = 0.0001) with HD. The frequency of HLA-DPB1*05:01 was significantly higher in GD patients than in HD patients (Pc = 0.0005). Furthermore, differences were found between patients with Thyroid associated ophthalmopathy (TAO) and those without TAO in the distribution of HLA-B*54:01 (8.6% vs. 30.6%, P = 0.04) and -C*03:03 (37.1% vs. 11.1%, P = 0.02). In the analysis of amino acid variants of HLA molecules, both Leu35 (OR = 23.38, P = 0.0002) and Glu55 (OR = 23.38, P = 0.0002) of HLA-DPB1 were strongly associated with GD and showed different distributions between GD and HD (P = 0.001). Our results suggest that HLA alleles, especially amino-acid signatures of the HLA-DP β chain, might contribute to the molecular pathogenesis of early-onset AITD.

Fine mapping MHC associations in Graves' disease and its clinical subtypes in Han Chinese

Background

The classical human leucocyte antigen (HLA) genes were the most important genetic determinant for Graves’ disease (GD). The aim of the study was to fine map causal variants of the HLA genes.

Methods

We applied imputation with a Pan-Asian HLA reference panel to thoroughly investigate themajor histocompatibility complex (MHC) associations with GD down to the amino acid level of classical HLA genes in 1468 patients with GD and 1490 controls of Han Chinese.

Results

The strongest finding across the HLA genes was the association with HLA-DPβ1 position 205 (P_omnibus=2.48×10⁻³³). HLA-DPA1*02:02 was the strongest association among the classical HLA alleles, which was in perfect linkage disequilibrium with HLA-DPα1 residue Met11 (OR=1.90, P_binary=1.76×10⁻³¹). Applying stepwise conditional analysis, we identified amino acid position 205 in HLA-DPβ1, position 66 and 99 in HLA-B and position 28 in HLA-DRβ1 explain majority of the MHC association to GD risk. We further evaluated risk of two clinical subtypes of GD, namely persistent thyroid stimulating hormone receptor antibody -positive (pTRAb+) group and ‘non-persistent TRAb positive’ (pTRAb−) group after antithyroid drug therapy. We found that HLA-B residues Lys66-Arg69-Val76 could drive pTRAb− GD risk alone, while HLA-DPβ1 position 205, HLA-B position 69 and 199 and HLA-DRβ1 position 28 drive pTRAb+ GD risk. The risk heterogeneity between pTRAb+ and pTRAb− GD might be driven by HLA-DPα1 Met11.

Conclusions

Four amino acid positions could account for the associations of MHC with GD in Han Chinese. These distinct HLA association patterns indicated the two subtypes have distinct molecular mechanisms of pathogenesis.

Future Directions of Genomics Research in Rheumatic Diseases

Recent developments in human genome genotyping and sequencing technologies, such as genome-wide association studies and whole-genome sequencing analyses, have successfully identified several risk genes of rheumatic diseases. Fine-mapping studies using the HLA imputation method revealed that classical and non-classical HLA genes contribute to the risk of rheumatic diseases. Integration of human disease genomics with biological, medical, and clinical databases should contribute to the elucidation of disease pathogenicity and novel drug discovery. Disease risk genes identified by large-scale genetic studies are considered to be promising resources for novel drug discovery, including drug repositioning and biomarker microRNA screening for rheumatoid arthritis.

Differences in Gene-Gene Interactions in Graves' Disease Patients Stratified by Age of Onset

Background

Graves’ disease (GD) is a complex disease in which genetic predisposition is modified by environmental factors. Each gene exerts limited effects on the development of autoimmune disease (OR = 1.2–1.5). An epidemiological study revealed that nearly 70% of the risk of developing inherited autoimmunological thyroid diseases (AITD) is the result of gene interactions. In the present study, we analyzed the effects of the interactions of multiple loci on the genetic predisposition to GD. The aim of our analyses was to identify pairs of genes that exhibit a multiplicative interaction effect.

Material and Methods

A total of 709 patients with GD were included in the study. The patients were stratified into more homogeneous groups depending on the age at time of GD onset: younger patients less than 30 years of age and older patients greater than 30 years of age. Association analyses were performed for genes that influence the development of GD: HLADRB1, PTPN22, CTLA4 and TSHR. The interactions among polymorphisms were analyzed using the multiple logistic regression and multifactor dimensionality reduction (MDR) methods.

Results

GD patients stratified by the age of onset differed in the allele frequencies of the HLADRB1*03 and 1858T polymorphisms of the PTPN22 gene (OR = 1.7, p = 0.003; OR = 1.49, p = 0.01, respectively). We evaluated the genetic interactions of four SNPs in a pairwise fashion with regard to disease risk. The coexistence of HLADRB1 with CTLA4 or HLADRB1 with PTPN22 exhibited interactions on more than additive levels (OR = 3.64, p = 0.002; OR = 4.20, p < 0.001, respectively). These results suggest that interactions between these pairs of genes contribute to the development of GD. MDR analysis confirmed these interactions.

Conclusion

In contrast to a single gene effect, we observed that interactions between the HLADRB1/PTPN22 and HLADRB1/CTLA4 genes more closely predicted the risk of GD onset in young patients.

Construction of a population-specific HLA imputation reference panel and its application to Graves' disease risk in Japanese

To fine map association signals of human leukocyte antigen (HLA) variants in the major histocompatibility complex (MHC) region, we constructed a Japanese population-specific reference panel (n = 908). We conducted trans-ancestry comparisons of linkage disequilibrium (LD) and haplotype structure for HLA variants using an entropy-based LD measurement, ɛ, and a visualization tool to capture high-dimensional variables. Our Japanese reference panel exhibited stronger LD between HLA genes than European or other East Asian populations, characterized by one population-specific common long-range HLA haplotype. We applied HLA imputation to genome-wide association study (GWAS) data for Graves' disease in Japanese (n = 9,003) and found that amino acid polymorphisms of multiple class I and class II HLA genes independently contribute to disease risk (HLA-DPB1, HLA-A, HLA-B and HLA-DRB1; P < 2.3 × 10(-6)), with the strongest impact at HLA-DPB1 (P = 1.6 × 10(-42)). Our study illustrates the value of population-specific HLA reference panels.

The clinical value of human leukocyte antigen HLA-DRB1 subtypes associated to Graves' disease in Romanian population

The aim of this study was to identify the primary susceptibility HLA-DRB1 alleles associated with GD in Romanian population and to seek whether specific HLA-DRB1 haplotypes are associated with differences in the clinical presentation of GD at diagnosis. Molecular typing of HLA-DRB1 alleles was performed in 77 Romanian Caucasian GD patients and 445 racially matched controls. In GD patients, age, presence of eye disease, goiter grade, autoantibody status and titer, TSH, FT4, FT3, TT3 levels were recorded at diagnosis. The allelic frequencies of HLA-DRB1*03 (41.55% vs. 17.75%, p < 0.0001, χ(2) = 20.81) and DRB1*11 (42.85% vs. 30.56%, p = 0.045, χ(2) = 3.98)were higher, whereas those of HLA-DRB1*01(3.89% vs. 16.40%, p = 0.007, χ(2) = 7.281) and DRB1*15 (10.38% vs. 21.34%, p = 0.038, χ(2) = 4.309)were lower in GD patients than in controls. FT4/TT3 ratio (p = 0.015) and anti-thyroglobulin antibodies (p = 0.024) were higher in *03/11 patients compared to *X/X, *11/Z, *03/Y patients (where X is any other allele than *03 and *11, Y is any other allele than *11, Z is any other allele than *03). In conclusion, HLA-DRB1*03 and DRB1*11 may be the primary susceptibility HLA-DRB1 alleles associated with GD in Romanian population, whereas HLA-DRB1*01 and DRB1*15 seem to be protective. At diagnosis, HLA-DRB1*03/11 GD patients had higher FT4/TT3 ratio and anti-thyroglobulin antibody levels.

Association between age at diagnosis of Graves' disease and variants in genes involved in immune response

Background

Graves' disease (GD) is a complex disease in which genetic predisposition is modified by environmental factors. The aim of the study was to examine the association between genetic variants in genes encoding proteins involved in immune response and the age at diagnosis of GD.

Methods

735 GD patients and 1216 healthy controls from Poland were included into the study. Eight genetic variants in the HLA-DRB1, TNF, CTLA4, CD40, NFKb, PTPN22, IL4 and IL10 genes were genotyped. Patients were stratified by the age at diagnosis of GD and the association with genotype was analysed.

Results

Polymorphism in the HLA-DRB1, TNF and CTLA4 genes were associated with GD. The carriers of the HLA DRB1*03 allele were more frequent in patients with age at GD diagnosis ≤30 years than in patients with older age at GD diagnosis.

Conclusions

HLADRB1*03 allele is associated with young age at diagnosis of Graves' disease in polish population.

Association between HLA-B*46 allele and Graves disease in Asian populations: a meta-analysis

Graves' disease (GD) is a leading cause of hyperthyroidism, which affects 1.0-1.6% of the general population. Previous studies reported a higher GD prevalence in Asian populations compared to Caucasian populations. The etiology of GD involves complex interactions between predisposing genes and environmental triggers. Genetic studies have shown that the human leukocyte antigen (HLA) is an important candidate genetic region associated with GD in Asian populations. However, the results were inconsistent and inconclusive. Here, we performed a meta-analysis to evaluate the role of the HLA-B*46 allele in GD in Asian populations. A total of 14 case-controlled studies on the association of the HLA-B*46 allele in 1743 GD patients and 5689 controls were included. Our results showed a trend toward an increased risk of GD in HLA-B*46-positive subjects compared to those HLA-B*46-negative (OR = 2.48; 95% CI = 1.96-3.13, P < 0.01). However, there were some limitations to the current meta-analysis, such as heterogeneity (P(heterogeneity )< 0.01 and I(2 )= 68.0%) or the different typing methods (serological and genotyping methods). The meta-analysis indicated that the HLA-B*46 allele is a risk factor for GD in Asian populations. Future studies on the role of the HLA-B*46 allele in GD should consider complications such as periodic paralysis, ophthalmopathy and recurrence.

Autoimmune thyroid disorders-An update

BACKGROUND

Autoimmune thyroid disease (AITD), a common organ specific autoimmune disorder is seen mostly in women between 30-50 yrs of age. Thyroid autoimmunity can cause several forms of thyroiditis ranging from hypothyroidism (Hashimoto's thyroiditis) to hyperthyroidism (Graves'Disease). Prevalence rate of autoimmune mediated hypothyroidism is about 0.8 per 100 and 95% among them are women. Graves' disease is about one tenth as common as hypothyroidism and tends to occur more in younger individuals. Both these disorders share many immunologic features and the disease may progress from one state to other as the autoimmune process changes. Genetic, environmental and endogenous factors are responsible for initiation of thyroid autoimmunity. At present the only confirmed genetic factor lies in HLA complex (HLA DR-3) and the T cell regulatory gene (CTLA 4). A number of environmental factors like viral infection, smoking, stress & iodine intake are associated with the disease progression. The development of antibodies to thyroid peroxidase (TPO) thyroglobulin (TG) and Thyroid stimulating hormone receptor (TSH R) is the main hallmark of AITD. Circulating T Lymphocytes are increased in AITD and thyroid gland is infiltrated with CD4+ and CD8+ T Cells. Wide varieties of cytokines are produced by infiltrated immune cells, which mediate cytotoxicity leading to thyroid cell destruction. Circulating antibodies to TPO and TG are measured by immunofluorescense, hemagglutination, ELISA & RIA. TSHR antibodies of Graves' disease can be measured in bioassays or indirectly in assays that detect antibody binding to the receptor.

Molecular pathogenesis of neuromyelitis optica

Neuromyelitis optica (NMO) is a rare autoimmune disorder, distinct from multiple sclerosis, causing inflammatory lesions in the optic nerves and spinal cord. An autoantibody (NMO IgG) against aquaporin-4 (AQP4), a water channel expressed on astrocytes is thought to be causative. Peripheral production of the antibody is triggered by an unknown process in genetically susceptible individuals. Anti-AQP4 antibody enters the central nervous system (CNS) when the blood brain barrier is made permeable and has high affinity for orthogonal array particles of AQP4. Like other autoimmune diseases, Th17 cells and their effector cytokines (such as interleukin 6) have been implicated in pathogenesis. AQP4 expressing peripheral organs are not affected by NMO IgG, but the antibody causes extensive astrocytic loss in specific regions of the CNS through complement mediated cytotoxicity. Demyelination occurs during the inflammatory process and is probably secondary to oligodendrocyte apoptosis subsequent to loss of trophic support from astrocytes. Ultimately, extensive axonal injury leads to severe disability. Despite rapid advances in the understanding of NMO pathogenesis, unanswered questions remain, particularly with regards to disease mechanisms in NMO IgG seronegative cases. Increasing knowledge of the molecular pathology is leading to improved treatment strategies.

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.

Association of susceptibility to multiple sclerosis in Southern Han Chinese with HLA-DRB1, -DPB1 alleles and DRB1-DPB1 haplotypes: distinct from other populations

Association of HLA class II with multiple sclerosis (MS) has been widely studied in both Western and Oriental populations. However, such an association is not well documented in Chinese. The objective of this study was to examine the association between the susceptibility to conventional MS in Southern Chinese with HLA-DRB1,-DPB1 alleles and putative DRB1-DPB1 haplotypes. Genotyping of HLA-DRB1 and -DPB1 alleles was performed in 60 patients with conventional MS and 95 controls. Allele frequencies were compared between patients and controls to identify MSassociated alleles. Relative predisposing effect method was used to compare haplotype frequencies in patients and controls and to identify possible predisposing DRB1-DPB1 haplotypes, which were further examined for differences in haplotype carriage rates between the two groups. We found that the allele frequency of DRB1*1501 was not different between patients (18.3%) and controls (21.1%) ( p = 0.837). In contrast, frequency of the DPB1*0501 allele was significantly higher in patients (90%) than in controls (67.4%) (odds ratio = 4.36, p = 0.0013, pcorr = 0.025). DRB1-DPB1 linkage haplotype in patients (8.33%) was significantly higher than in controls (0%) ( p < 0.0001) and the carriage rate of this haplotype was significantly increased in patients (15%) as compared with controls (0%) ( p = 0.00013, pcorr = 0.003). Combined, these results suggest that HLA-DRB1*1501 is not associated with susceptibility to conventional MS in Southern Chinese. Instead, both the DPB1*0501 allele and the DRB1*1602- DPB1*0501 haplotype are strong predisposing factors for conventional MS in this population. Our results establish that the HLA profiles of MS in Southern Chinese are distinct from other populations.

New HLA DRB1 and DQB1 haplotypes in a pedigree of familial Graves' disease in Japan

The present study demonstrated genetic analysis of human leukocyte antigen (HLA) in a familial Graves' disease linked to autoimmune mechanism. The proband was a 17 year-old female. At 15 years, Graves' disease was diagnosed with serum TSH was <0.015 IU/ml; free T(3), 13.6 pg/ml; free T(4), 4.51 ng/dl; and TSH receptor antibody (TRAb), 94.1%. She had two brothers (19 and 13 years-old), who manifested Graves' disease at 18 and 13 years, respectively. They also had elevated TRAb as high as 48.4 and 49.1%, respectively. There was a strong family history of Graves' disease in their maternal pedigree. Namely, their two aunts and a cousin had Graves' disease, and their onset ages of Graves' disease were also during their teen-age years. However, there was no patient with Graves' disease in the paternal pedigree. We checked HLA-DRB and -DQB haplotype in the members of maternal pedigree and proband's father. The members of maternal pedigree including both affected and unaffected Graves' disease had haplotypes of DRB1*150101 and DQB1*0602, except for the cousin who had DRB1*140301 and DQB1*030101. The haplotypes of DRB1*150101 and DQB1*0602 were different from susceptible HLA types in Japanese childhood onset Graves' disease. However, two cases of Graves' disease also had HLA types of DRB1*40501 and DQB1*0401, in addition to the haplotypes of DRB1*150101 and DQB1*0602. There was no other autoimmune disease including type 1 diabetes mellitus in their family. The present findings indicated that familial Graves' disease was found mainly in the maternal females and become overt during their teen-age years. They had new HLA haplotypes distinct from those susceptibly in Japanese Graves' patients. Further study will be necessary to analyze the mutant locus of DNA to elucidate pathogenesis of familial Graves' disease.

HLA-DQ haplotypes in Spanish and German families with Graves' disease: contribution to DQA1*0501-DQB1*0301 mediated genetic susceptibility from fathers

Genetic and environmental factors are involved in the pathogenesis of Graves' disease. The human leukocyte antigen (HLA) locus is considered to be one risk factor for Graves' disease but parent of origin effects have not been studied. Therefore, we investigated the transmission of HLA risk haplotypes DQA1*0501, DQA1*0501-DQB1*0201 (DQ2), and DQA1*0501-DQB1*0301 (DQ7) in two Graves' disease family-cohorts from Spain and Germany. Altogether 208 trio-families (109 from Spain and 99 from Germany; n = 624 individuals) with Graves' disease were genotyped for HLA-DQ alleles DQA1*0501 and the haplotypes DQA1*0501-DQB1*0201 (DQ2) and DQA1*0501-DQB1*0301 (DQ7). Since both family groups-German and Spanish-showed the same pattern of HLA transmission and nontransmission, they were analyzed together. HLA DQA1*0501 and DQA1*0501-DQB1*0201 (DQ2) were significantly overtransmitted from the parents to the affected offspring (204 vs. 131, p = 0.0057, pc = 0.0228 and 109 vs. 55, p = 0.0036, pc = 0.0144, respectively). These haplotypes were preferentially transmitted from fathers and DQA1*0501-DQB1*0301 (DQ7) was also more prevalent in fathers (24.0% vs. 17.1%, p = 0.0162, pc = 0.0648). We conclude, that HLA DQA1*0501 and DQA1*0501-DQB1*0201 (DQ2) are strongly associated with Graves' disease in both populations. A parent of origin effect of risk haplotypes can not be excluded at present, warranting further family studies.

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.

A C/T polymorphism in the 5' untranslated region of the CD40 gene is associated with later onset of Graves' disease in Japanese

Graves' disease (GD) is an autoimmune disorder with genetic predisposition. CD40, which stimulates lymphocyte proliferation and differentiation, is an important immunomodulator and is expressed in the thyroid follicular cells as well as antigen-presenting cells. A single nucleotide polymorphism (SNP) at position -1 of the Kozak sequence of the CD40 gene has been reported to be associated with the development of GD. The aim of the present study was to investigate whether CD40 gene polymorphism confers susceptibility to GD in Japanese. CD40 gene polymorphisms were studied in Japanese GD patients (n = 324) and healthy control subjects without anti-thyroid autoantibodies or a family history of autoimmune disorders (n = 229). A C/T polymorphism at position -1 of the CD40 gene was measured using the polymerase chain reaction restriction fragment length polymorphism. There was no significant difference in allele or genotype frequency of the CD40 SNP between GD and control subjects. There was a significant decrease in the TT genotype frequency in the GD patients, who developed GD after 40 years old, than those under 40 year of age. These data suggest that the SNP of CD40 gene is associated with susceptibility to later onset of GD in Japanese.

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.

Association of a thyroglobulin gene polymorphism with Hashimoto's thyroiditis in the Japanese population

OBJECTIVE

The aetiology of the autoimmune thyroid diseases (AITDs), Graves' disease (GD) and Hashimoto's thyroiditis is largely unknown. However, genetic susceptibility is believed to play a major role. Two whole genome scans from Japan and from the USA identified a locus on chromosome 8q24 which showed evidence for linkage with AITD and HT. Recent studies have demonstrated an association between a Tg polymorphisms and AITD, suggesting that Tg is the susceptibility gene on 8q24.

PATIENTS

We studied 308 Japanese AITD patients (194 GD and 114 HT patients) and 417 Japanese control subjects in association studies.

DESIGN

Case-control association studies were performed using D8S284 and D8S272, microsatellite markers located in the 8q24 region, Tgms1 and Tgms2, microsatellite markers in introns 10 and 27, respectively, of Tg, and a SNP in exon 33 of Tg.

RESULTS

No differences in allele frequencies were observed between AITD patients and controls for D8S284, D8S272 and Tgms1. Similarly, for Tgms2 and the exon 33 SNP no significant differences in allele frequency distribution were observed for all AITD patients. However, when analysing the HT patients alone we found a significant association between the 330 bp/352 bp genotype of Tgms2 and HT (HT = 16.7%, controls = 7.1%; corrected P-value = 0.01, OR = 2.6).

CONCLUSION

Our results confirm the previous reports of an association between the Tg gene and AITD and suggest that Tg is an AITD susceptibility gene.

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.

HLA-DRB1*08, DRB1*03/DRB3*0101, and DRB3*0202 are susceptibility genes for Graves' disease in North American Caucasians, whereas DRB1*07 is protective

Graves' disease is known to be HLA-D associated; however, the primary loci involved remain unclear. We examined HLA genotypes of DRB1 and DQB1 plus DRB3 subtypes using PCR-based sequence-specific priming in two groups of North American (Gainesville, FL; and Toronto, Canada) Caucasian patients with Graves' disease. We stratified patients into those with either early age at onset (<20 yr; 13.1 +/- 4.8 yr; n = 30) and later age at onset of disease (38.8 +/- 9.7 yr; n = 62) and compared the results to 192 normal controls. As expected, we found that DRB1*03 was associated with Graves' disease, but at a higher odds ratios for early-onset than later-onset patients (3.7 vs. 2.2). The frequency of DRB1*08 was also increased in both groups of patients, but significantly so only in patients with early-onset Graves' (P = 0.001; chi2 = 10.8). DRB3 was highly associated with Graves' in both groups of patients (P = 0.009; chi2 = 6.83 and P = 0.0015; chi2 = 10.1, respectively); however, the subtypes of DRB3 revealed differential susceptibilities. Whereas the frequencies of both DRB3*0101 and DRB3*0202 were increased over the entire cohort, that of DRB3*0301 was not. Significant P values were found for DRB3*0101 in patients with early-onset and for DRB3*0202 in patients with later onset of Graves' disease. When the haplotypes of DRB1*03-DRB3 of all subtypes were removed for analysis (all DRB1*03 positive also had DRB3*0101), the frequency of DRB3*0202 remained significantly higher in the patients with later onset of Graves' disease than in controls (P = 0.0043; chi2 = 8.13), but DRB3 was no longer positively associated with the early-onset group. In addition, we found that DRB1*07 was negatively associated with both groups of patients (P = 0.024; chi2 = 5.10 and P = 0.0085; chi2 = 6.93). These data suggest that DRB3*0202 is more likely to be the primary susceptible locus than DRB1*03 for patients with later onset of Graves' disease.

The inter-locus recombinant HLA-B*4601 has high selectivity in peptide binding and functions characteristic of HLA-C

The vast majority of new human HLA class I alleles are formed by conversions between existing alleles of the same locus. A notable exception to this rule is HLA-B*4601 formed by replacement of residues 66-76 of the alpha 1 helix of B*1501 by the homologous segment of Cw*0102. This inter-locus recombination, which brings together characteristic elements of HLA-B and HLA-C structure, is shown here to influence function dramatically. Naturally processed peptides bound by B*4601 are distinct from those of its parental allotypes B*1501 and Cw*0102 and dominated by three high abundance peptides. Such increased peptide selectivity by B*4601 is unique among HLA-A,B,C allotypes. For other aspects of function, presence of the small segment of HLA-C-derived sequence in an otherwise HLA-B framework converts B*4601 to an HLA-C-like molecule. Alloreactive cytotoxic T lymphocytes (CTL), natural killer (NK) cells, and cellular glycosidases all recognize B*4601 as though it were an HLA-C allotype. These unusual properties are those of an allotype which has frequencies as high as 20% in south east Asian populations and is associated with predisposition to autoimmune diseases and nasopharyngeal carcinoma.

Increased frequency of HLA DR13 in hepatitis C virus carriers with persistently normal ALT levels

The aim of this study was to clarify the relationship between human leukocyte antigen DR allele distribution and the degree of liver cell injury of hepatitis C virus (HCV) carriers in Japan. The subjects, 68 HCV carriers, were divided into two groups according to the laboratory data and liver histology. Those in the asymptomatic carrier group (n = 19) had normal ALT levels persistently for 8-153 months (mean 25.7 months) and were diagnosed histologically as normal liver, nonspecific reactive hepatitis or chronic persistent hepatitis. Those in the chronic active hepatitis group (n = 49) had elevated ALT levels and were diagnosed histologically with chronic active hepatitis. The human leukocyte antigen DR alleles of all subjects were defined using the polymerase chain reaction restriction fragment length polymorphism method. The expression of human leukocyte antigen class I antigen and intercellular adhesion molecule 1 on the hepatocyte membrane were also examined in 14 patients from each group using an indirect immunohistochemical method. The frequency of DR13 (42.1%) in the asymptomatic carrier group was significantly higher (Pc < 0.003) than that of the chronic active hepatitis group (4.1%). There were no significant differences for the other DR alleles. The frequencies of expression of human leukocyte antigen class I antigen and intercellular adhesion molecule 1 on the hepatocyte membrane of the asymptomatic carrier group were significantly less than those of the chronic hepatitis group (64% vs. 100% P < 0.05, 29% vs. 71% P < 0.05, respectively), although there was no significant difference in the serum HCV-RNA titer between the two groups (10(6.4 +/- 1.1) vs. 10(6.5 +/- 0.7) copies/mL). These results demonstrate that the cellular immune response of the asymptomatic carrier group is less activated than the response of the chronic active hepatitis group and that HLA DR13 may be closely associated with this low activity of hepatitis among HCV carriers.