Complex interaction between HLA DR and DQ in conferring risk for childhood type 1 diabetes

Association between sarcoidosis and HLA polymorphisms in a Czech population from Central Europe: focus on a relationship with clinical outcome and treatment

Background

Sarcoidosis is an immune-mediated systemic disease with unknown etiology affecting the lung predominantly. The clinical manifestation of sarcoidosis is rather diverse ranging from Löfgren's syndrome to fibrotic disease. Also, it differs among patients with distinct geographical and ethnic origins, consistent with environmental and genetic factors' role in its pathogenesis. Of those, the polymorphic genes of the HLA system have been previously implicated in sarcoidosis. Therefore, we have performed an association study in a well-defined cohort of Czech patients aiming to define how variation in HLA genes, may contribute to disease origin and development.

Materials and methods

Total of the 301 Czech unrelated sarcoidosis patients were diagnosed according to international guidelines. In those, HLA typing was performed using next-generation sequencing. The allele frequencies at six HLA loci (HLA-A,-B,-C,-DRB1,-DQA1, and -DQB1) observed in the patients were compared with HLA allele distribution determined in 309 unrelated healthy Czech subjects; sub-analyses of relationships between HLA and distinct sarcoidosis clinical phenotypes were performed. Associations were assessed by two-tailed Fischer's exact test with correction for multiple comparisons.

Results

We report two variants, HLA-DQB1*06:02, and HLA-DQB1*06:04, as risk factors for sarcoidosis, and three variants, HLA-DRB1*01:01, HLA-DQA1*03:01, and HLA-DQB1*03:02 as protective factors. HLA-B*08:01, HLA-C*07:01, HLA-DRB1*03:01, HLA-DQA1*05:01, and HLA-DQB1*02:01 variants associated with Löfgren's syndrome, a more benign phenotype. HLA- DRB1*03:01 and HLA-DQA1*05:01 alleles were connected with better prognosis-chest X-ray (CXR) stage 1, disease remission, and non-requirement of corticosteroid treatment. The alleles HLA-DRB1*11:01 and HLA-DQA1*05:05 are associated with more advanced disease represented by the CXR stages 2-4. HLA-DQB1*05:03 associated with sarcoidosis extrapulmonary manifestation.

Conclusion

In our Czech cohort, we document some associations between sarcoidosis and HLA previously described in other populations. Further, we suggest novel susceptibility factors for sarcoidosis, such as HLA-DQB1*06:04, and characterize associations between HLA and sarcoidosis clinical phenotypes in Czech patients. Our study also extends the role of the 8.1 ancestral haplotype (HLA-A*01:01∼HLA-B*08:01∼HLA-C*07:01∼HLA-DRB1*03:01∼HLA-DQA1*05:01∼HLA-DQB1*02:01), already implicated in autoimmune diseases, as a possible predictor of better prognosis in sarcoidosis. The general translational application of our newly reported findings for personalized patient care should be validated by an independent study from another, international referral center.

Human Leukocyte Antigens class II (HLA II) gene profile from an admixed population of patients with type 1 diabetes with severe diabetic retinopathy: a nested case-control study in Brazil

BACKGROUND

Although the well-established role of the HLA genes on the predisposition of type 1 diabetes (T1D), its contribution to the development and progression of diabetic retinopathy is still unclear, especially in admixed populations. We aimed to study the relationship between HLA alleles and severe diabetic retinopathy in a highly admixed population of T1D patients.

METHODS

This was a nested case-control study based on a cross-sectional, nationwide survey conducted in Brazil. We included 117 patients with severe diabetic retinopathy and 117 random controls composed of T1D patients without retinopathy, matched for diabetes duration. HLA-class II genes (HLA-DRB1, -DQA1, and -DQB1) were genotyped using the SSO and NGS methods.

RESULTS

Haplotypes HLA-DRB1*04:05 ~ DQA1*03:01 g ~ DQB1*03:02 (OR 1.75, CI 0.97-3.16, p value 0.058) and HLA-DRB1*13:02 ~ DQA1*01:02 ~ DQB1*06:04 (OR 5.18, CI 1.12-23.09, p value 0.019) were more prevalent on the severe DR group but they did not present statistically difference after Bonferroni correction. The most frequent haplotype on both groups was HLA-DRB1*03:01 ~ DQA1*05:01 g ~ DQB1*02:01 (29.6% on severe DR and 33.33% on the control group).

CONCLUSIONS

Our study showed no influence of HLA genes on the development of DR. Further longitudinal data is needed to better understand the role of genetic factors on this multifactorial significant microvascular complication.

Next-Generation HLA Sequence Analysis Uncovers Seven HLA-DQ Amino Acid Residues and Six Motifs Resistant to Childhood Type 1 Diabetes

HLA-DQA1 and -DQB1 genes have significant and potentially causal associations with autoimmune type 1 diabetes (T1D). To follow up on the earlier analysis on high-risk HLA-DQ2.5 and DQ8.1, the current analysis uncovers seven residues (αa1, α157, α196, β9, β30, β57, and β70) that are resistant to T1D among subjects with DQ4-, 5-, 6-, and 7-resistant DQ haplotypes. These 7 residues form 13 common motifs: 6 motifs are significantly resistant, 6 motifs have modest or no associations (P values >0.05), and 1 motif has 7 copies observed among control subjects only. The motifs "DAAFYDG," "DAAYHDG," and "DAAYYDR" have significant resistance to T1D (odds ratios [ORs] 0.03, 0.25, and 0.18; P = 6.11 × 10^-24, 3.54 × 10^-15, and 1.03 × 10^-21, respectively). Remarkably, a change of a single residue from the motif "DAAYHDG" to "DAAYHSG" (D to S at β57) alters the resistance potential, from resistant motif (OR 0.15; P = 3.54 × 10^-15) to a neutral motif (P = 0.183), the change of which was significant (Fisher P value = 0.0065). The extended set of linked residues associated with T1D resistance and unique to each cluster of HLA-DQ haplotypes represents facets of all known features and functions of these molecules: antigenic peptide binding, peptide-MHC class II complex stability, β167-169 RGD loop, T-cell receptor binding, formation of homodimer of α-β heterodimers, and cholesterol binding in the cell membrane rafts. Identification of these residues is a novel understanding of resistant DQ associations with T1D. Our analyses endow potential molecular approaches to identify immunological mechanisms that control disease susceptibility or resistance to provide novel targets for immunotherapeutic strategies.

Motifs of Three HLA-DQ Amino Acid Residues (α44, β57, β135) Capture Full Association With the Risk of Type 1 Diabetes in DQ2 and DQ8 Children

HLA-DQA1 and -DQB1 are strongly associated with type 1 diabetes (T1D), and DQ8.1 and DQ2.5 are major risk haplotypes. Next-generation targeted sequencing of HLA-DQA1 and -DQB1 in Swedish newly diagnosed 1- to 18 year-old patients (n = 962) and control subjects (n = 636) was used to construct abbreviated DQ haplotypes, converted into amino acid (AA) residues, and assessed for their associations with T1D. A hierarchically organized haplotype (HOH) association analysis allowed 45 unique DQ haplotypes to be categorized into seven clusters. The DQ8/9 cluster included two DQ8.1 risk and the DQ9 resistant haplotypes, and the DQ2 cluster included the DQ2.5 risk and DQ2.2 resistant haplotypes. Within each cluster, HOH found residues α44Q (odds ratio [OR] 3.29, P = 2.38 * 10^-85) and β57A (OR 3.44, P = 3.80 * 10^-84) to be associated with T1D in the DQ8/9 cluster representing all ten residues (α22, α23, α44, α49, α51, α53, α54, α73, α184, β57) due to complete linkage disequilibrium (LD) of α44 with eight such residues. Within the DQ2 cluster and due to LD, HOH analysis found α44C and β135D to share the risk for T1D (OR 2.10, P = 1.96 * 10^-20). The motif "QAD" of α44, β57, and β135 captured the T1D risk association of DQ8.1 (OR 3.44, P = 3.80 * 10^-84), and the corresponding motif "CAD" captured the risk association of DQ2.5 (OR 2.10, P = 1.96 * 10^-20). Two risk associations were related to GAD65 autoantibody (GADA) and IA-2 autoantibody (IA-2A) but in opposite directions. CAD was positively associated with GADA (OR 1.56, P = 6.35 * 10^-8) but negatively with IA-2A (OR 0.59, P = 6.55 * 10^-11). QAD was negatively associated with GADA (OR 0.88; P = 3.70 * 10^-3) but positively with IA-2A (OR 1.64; P = 2.40 * 10^-14), despite a single difference at α44. The residues are found in and around anchor pockets 1 and 9, as potential T-cell receptor contacts, in the areas for CD4 binding and putative homodimer formation. The identification of three HLA-DQ AAs (α44, β57, β135) conferring T1D risk should sharpen functional and translational studies.

HLA class II genotyping of admixed Brazilian patients with type 1 diabetes according to self-reported color/race in a nationwide study

The HLA region is responsible for almost 50% of the genetic risk of type 1 diabetes (T1D). However, haplotypes and their effects on risk or protection vary among different ethnic groups, mainly in an admixed population. We aimed to evaluate the HLA class II genetic profile of Brazilian individuals with T1D and its relationship with self-reported color/race. This was a nationwide multicenter study conducted in 10 Brazilian cities. We included 1,019 T1D individuals and 5,116 controls matched for the region of birth and self-reported color/race. Control participants belonged to the bone marrow transplant donor registry of Brazil (REDOME). HLA-class II alleles (DRB1, DQA1, and DQB1) were genotyped using the SSO and NGS methods. The most frequent risk and protection haplotypes were HLA~DRB1*03:01~DQA1*05:01 g~DQB1*02:01 (OR 5.8, p < 0.00001) and HLA~DRB1*07:01~DQA1*02:01~DQB1*02:02 (OR 0.54, p < 0.0001), respectively, regardless of self-reported color/race. Haplotypes HLA~DRB1*03:01~DQA1*05:01 g~DQB1*02:01 and HLA~DRB1*04:02~DQA1*03:01 g~DQB1*03:02 were more prevalent in the self-reported White group than in the Black group (p = 0.04 and p = 0.02, respectively). The frequency of haplotype HLA~DRB1*09:01~DQA1*03:01 g~DQB1*02:02 was higher in individuals self-reported as Black than White (p = <0.00001). No difference between the Brazilian geographical regions was found. Individuals with T1D presented differences in frequencies of haplotypes within self-reported color/race, but the more prevalent haplotypes, regardless of self-reported color/race, were the ones described previously in Europeans. We hypothesize that, in the T1D population of Brazil, although highly admixed, the disease risk alleles come mostly from Europeans as a result of centuries of colonization and migration.

Eleven Amino Acids of HLA-DRB1 and Fifteen Amino Acids of HLA-DRB3, 4, and 5 Include Potentially Causal Residues Responsible for the Risk of Childhood Type 1 Diabetes

Next-generation targeted sequencing of HLA-DRB1 and HLA-DRB3, -DRB4, and -DRB5 (abbreviated as DRB345) provides high resolution of functional variant positions to investigate their associations with type 1 diabetes risk and with autoantibodies against insulin (IAA), GAD65 (GADA), IA-2 (IA-2A), and ZnT8 (ZnT8A). To overcome exceptional DR sequence complexity as a result of high polymorphisms and extended linkage disequilibrium among the DR loci, we applied a novel recursive organizer (ROR) to discover disease-associated amino acid residues. ROR distills disease-associated DR sequences and identifies 11 residues of DRB1, sequences of which retain all significant associations observed by DR genes. Furthermore, all 11 residues locate under/adjoining the peptide-binding groove of DRB1, suggesting a plausible functional mechanism through peptide binding. The 15 residues of DRB345, located respectively in the β49-55 homodimerization patch and on the face of the molecule shown to interact with and bind to the accessory molecule CD4, retain their significant disease associations. Further ROR analysis of DR associations with autoantibodies finds that DRB1 residues significantly associated with ZnT8A and DRB345 residues with GADA. The strongest association is between four residues (β14, β25, β71, and β73) and IA-2A, in which the sequence ERKA confers a risk association (odds ratio 2.15, P = 10^-18), and another sequence, ERKG, confers a protective association (odds ratio 0.59, P = 10^-11), despite a difference of only one amino acid. Because motifs of identified residues capture potentially causal DR associations with type 1 diabetes, this list of residuals is expected to include corresponding causal residues in this study population.

The Better Diabetes Diagnosis (BDD) study - A review of a nationwide prospective cohort study in Sweden

The incidence of type 1 diabetes (T1D) in Sweden is one of the highest in the world. However, the possibility of other types of diabetes must also be considered. In addition, individuals with T1D constitute a heterogeneous group. A precise classification of diabetes is a prerequisite for optimal outcome. For precise classification, knowledge on the distribution of genetic factors, biochemical markers and clinical features in individuals with new onset of diabetes is needed. The Better Diabetes Diagnosis (BDD), is a nationwide study in Sweden with the primary aim to facilitate a more precise classification and diagnosis of diabetes in order to enable the most adequate treatment for each patient. Secondary aims include identification of risk factors for diabetes-related co-morbidities. Since 2005, data on almost all children and adolescents with newly diagnosed diabetes in Sweden are prospectively collected and including heredity of diabetes, clinical symptoms, levels of C peptide, genetic analyses and detection of autoantibodies. Since 2011, analyses of HLA profile, autoantibodies and C peptide levels are part of clinical routine in Sweden for all pediatric patients with suspected diagnosis of diabetes. In this review, we present the methods and main results of the BDD study so far and discuss future aspects.

Fast and general tests of genetic interaction for genome-wide association studies

A complex disease has, by definition, multiple genetic causes. In theory, these causes could be identified individually, but their identification will likely benefit from informed use of anticipated interactions between causes. In addition, characterizing and understanding interactions must be considered key to revealing the etiology of any complex disease. Large-scale collaborative efforts are now paving the way for comprehensive studies of interaction. As a consequence, there is a need for methods with a computational efficiency sufficient for modern data sets as well as for improvements of statistical accuracy and power. Another issue is that, currently, the relation between different methods for interaction inference is in many cases not transparent, complicating the comparison and interpretation of results between different interaction studies. In this paper we present computationally efficient tests of interaction for the complete family of generalized linear models (GLMs). The tests can be applied for inference of single or multiple interaction parameters, but we show, by simulation, that jointly testing the full set of interaction parameters yields superior power and control of false positive rate. Based on these tests we also describe how to combine results from multiple independent studies of interaction in a meta-analysis. We investigate the impact of several assumptions commonly made when modeling interactions. We also show that, across the important class of models with a full set of interaction parameters, jointly testing the interaction parameters yields identical results. Further, we apply our method to genetic data for cardiovascular disease. This allowed us to identify a putative interaction involved in Lp(a) plasma levels between two ‘tag’ variants in the LPA locus (p = 2.42 ⋅ 10⁻⁰⁹) as well as replicate the interaction (p = 6.97 ⋅ 10⁻⁰⁷). Finally, our meta-analysis method is used in a small (N = 16,181) study of interactions in myocardial infarction.

Interaction between organic molecules forms the basis of all biological systems. The availability of high-throughput genotyping and sequencing platforms enables us to cost-effectively genotype a large number of individuals. For sufficiently large datasets it is possible to reconstruct the genetic dependencies that underlie complex traits and diseases. However, there is a need for efficient statistical methodologies that can tackle the large sample size and computational resources required to study interaction. In this work we provide theory that reduces the required computational resources, and enable multiple research groups to effectively combine their results.

Integrated analysis of different microarray studies to identify candidate genes in type 1 diabetes

BACKGROUND

Type 1 diabetes (T1D), an autoimmune disease, occurs most commonly in children. Identifying altered gene expression in peripheral blood mononuclear cells (PBMCs) of T1D may lead to new strategies for preserving or improving β-ell function in patients with T1D.

METHODS

The Gene Expression Omnibus database was searched for microarray studies in PBMCs of T1D. Subsequently, gene expression datasets from multiple microarray studies were integrated to obtain differentially expressed genes (DEGs) between T1D and normal controls (NC). Gene function analysis was performed to determine the functions of the DEGs identified.

RESULTS

Four microarray studies were available for analysis, including 199 T1D samples and 74 NC samples. Analysis revealed 695 genes that were significantly differentially expressed in PBMCs from T1D compared with NC samples, with 450 upregulated and 245 downregulated. Signal transduction (gene ontology [GO]: 0007165; false discovery rate [FDR] = 1.54 × 10^-7 ) and protein binding (GO: 0005515; FDR = 2.93 × 10^-24 ) were significantly enriched for the GO categories of biological processes and molecular functions, respectively. The most significant pathway in the Kyoto Encyclopedia of Genes and Genomes analysis was arachidonic acid metabolism (FDR = 1.44 × 10^-3 ). Protein-protein interaction network analysis showed that the significant hub proteins contained immature colon carcinoma transcript 1 (ICT1; degree = 214; clustering coefficient [C] = 4.39 × 10^-5 ), zinc finger and BTB domain containing 16 (ZBTB16; degree = 112; C = 8.04 × 10^-4 ), and SERTA domain containing 1 (SERTAD1; degree = 38; C = 0.0014).

CONCLUSIONS

This integrated analysis will help develop improved therapies and interventions for T1D by identifying novel drug targets.

Next-Generation Sequencing Reveals That HLA-DRB3, -DRB4, and -DRB5 May Be Associated With Islet Autoantibodies and Risk for Childhood Type 1 Diabetes

The possible contribution of HLA-DRB3, -DRB4, and -DRB5 alleles to type 1 diabetes risk and to insulin autoantibody (IAA), GAD65 (GAD autoantibody [GADA]), IA-2 antigen (IA-2A), or ZnT8 against either of the three amino acid variants R, W, or Q at position 325 (ZnT8RA, ZnT8WA, and ZnT8QA, respectively) at clinical diagnosis is unclear. Next-generation sequencing (NGS) was used to determine all DRB alleles in consecutively diagnosed patients ages 1-18 years with islet autoantibody-positive type 1 diabetes (n = 970) and control subjects (n = 448). DRB3, DRB4, or DRB5 alleles were tested for an association with the risk of DRB1 for autoantibodies, type 1 diabetes, or both. The association between type 1 diabetes and DRB1*03:01:01 was affected by DRB3*01:01:02 and DRB3*02:02:01. These DRB3 alleles were associated positively with GADA but negatively with ZnT8WA, IA-2A, and IAA. The negative association between type 1 diabetes and DRB1*13:01:01 was affected by DRB3*01:01:02 to increase the risk and by DRB3*02:02:01 to maintain a negative association. DRB4*01:03:01 was strongly associated with type 1 diabetes (P = 10(-36)), yet its association was extensively affected by DRB1 alleles from protective (DRB1*04:03:01) to high (DRB1*04:01:01) risk, but its association with DRB1*04:05:01 decreased the risk. HLA-DRB3, -DRB4, and -DRB5 affect type 1 diabetes risk and islet autoantibodies. HLA typing with NGS should prove useful to select participants for prevention or intervention trials.

HLA-DQ genetic risk gradient for type 1 diabetes and celiac disease in northwestern Mexico

BACKGROUND

Type 1 diabetes (T1D) and celiac disease (CD) are the 2 most common autoimmune childhood diseases that share their HLA-DQ2 and DQ8 genetic origin. There has currently been an increase in both diseases worldwide. In children from the low-population State of Sonora (15 inhabitants/km(2)) in north-western Mexico, there is no information on their genetic risk or the distribution of the related alleles in the general population.

AIMS

To compare the HLA-DQ allele frequency in a representative sample of newborns from Sonora with that of T1D and CD patients to determine the risk gradient, and to identify the presence of celiac autoimmunity in the T1D group.

METHODS

The study included 397 Sonoran newborns, with 44 cases of T1D, and 25 CD cases. The CD and T1D cases were clinically diagnosed by specialists at the Hospital Infantil del Estado de Sonora, and the autoantibodies were determined by ELISA. Whole blood was collected, gDNA was extracted, and HLA-DQ2 and DQ8 were typed by PCR-SSP. The risk gradient was calculated by comparing the allele frequencies of the cases with those of the newborns.

RESULTS

The Sonoran HLA-DQ risk heterodimer proportion was 16.1% for HLA-DQ2 and 13.6% for HLA-DQ8, with an HLA-DQ2:HLA-DQ8 ratio of 1.2:1. The DQ8/DQ2 genotype represented a 1:14 risk for T1D, whereas the DQ8/DQB1*0201 combination showed a 1:6 risk for CD. The prevalence of CD autoimmunity in T1D children was 7%.

CONCLUSION

The Sonoran population has a distinctive HLA-DQ allele distribution due to its ancestry. The HLA-DQ8 combinations with DQ2 or one of its alleles conferred the highest risk for both diseases, and T1D and CD frequently appear together.

Type 1 diabetes and polyglandular autoimmune syndrome: A review

Type 1 diabetes (T1D) is an autoimmune disorder caused by inflammatory destruction of the pancreatic tissue. The etiopathogenesis and characteristics of the pathologic process of pancreatic destruction are well described. In addition, the putative susceptibility genes for T1D as a monoglandular disease and the relation to polyglandular autoimmune syndrome (PAS) have also been well explored. The incidence of T1D has steadily increased in most parts of the world, especially in industrialized nations. T1D is frequently associated with autoimmune endocrine and non-endocrine diseases and patients with T1D are at a higher risk for developing several glandular autoimmune diseases. Familial clustering is observed, which suggests that there is a genetic predisposition. Various hypotheses pertaining to viral- and bacterial-induced pancreatic autoimmunity have been proposed, however a definitive delineation of the autoimmune pathomechanism is still lacking. In patients with PAS, pancreatic and endocrine autoantigens either colocalize on one antigen-presenting cell or are expressed on two/various target cells sharing a common amino acid, which facilitates binding to and activation of T cells. The most prevalent PAS phenotype is the adult type 3 variant or PAS type III, which encompasses T1D and autoimmune thyroid disease. This review discusses the findings of recent studies showing noticeable differences in the genetic background and clinical phenotype of T1D either as an isolated autoimmune endocrinopathy or within the scope of polyglandular autoimmune syndrome.

Type I diabetes mellitus: genetic factors and presumptive enteroviral etiology or protection

We review type 1 diabetes and host genetic components, as well as epigenetics and viruses associated with type 1 diabetes, with added emphasis on the enteroviruses, which are often associated with triggering the disease. Genus Enterovirus is classified into twelve species of which seven (Enterovirus A, Enterovirus B, Enterovirus C, and Enterovirus D and Rhinovirus A, Rhinovirus B, and Rhinovirus C) are human pathogens. These viruses are transmitted mainly by the fecal-oral route; they may also spread via the nasopharyngeal route. Enterovirus infections are highly prevalent, but these infections are usually subclinical or cause a mild flu-like illness. However, infections caused by enteroviruses can sometimes be serious, with manifestations of meningoencephalitis, paralysis, myocarditis, and in neonates a fulminant sepsis-like syndrome. These viruses are often implicated in chronic (inflammatory) diseases as chronic myocarditis, chronic pancreatitis, and type 1 diabetes. In this review we discuss the currently suggested mechanisms involved in the viral induction of type 1 diabetes. We recapitulate current basic knowledge and definitions.

HLA-alleles associated with increased risk for extra-pulmonary involvement in sarcoidosis

Genetic factors influence the risk for disease as well as the clinical picture seen in sarcoidosis and especially the genes localized to the human leukocyte antigen (HLA) region on chromosome 6 are of importance. The aim of this study was to further investigate associations between HLA-DRB1 alleles and the risk for extra-pulmonary manifestations (EPMs), i.e. engagement of the skin, superficial lymph nodes, eyes, nervous system, kidneys, hypercalcemia, parotid and salivary glands, heart, liver, spleen and bone marrow in Scandinavian sarcoidosis patients. One thousand patients with together with a group of 2000 healthy individuals, matched for sex and age. HLA-DRB1 alleles were determined for all patients and controls. Excluding erythema nodosum and ankle arthritis, we found 288 of 1000 patients to have EPMs. There were 383 patients with Löfgren's syndrome (LS), and among them EPM were relatively uncommon and diagnosed in only 31 (8.1%) of the patients. In contrast, among the 617 non-LS patients, 257 (41.6%) had EPM (P < 0.0001). In LS patients, the absence of HLA-DRB1*03 substantially increased the risk factor for EPM (erythema nodosum and ankle arthritis excluded) (P < 0.0001). A distinct HLA allele combination, HLA-DRB1*04/*15, was identified as a risk factor for EPM in all patients (25 of 50 with DRB1*04/15 had EPM). In conclusion, EPM are common in non-LS sarcoidosis. Furthermore, HLA-typing of sarcoidosis patients can be used in the clinic to identify patients with an increased risk for EPM.

Multiple HLA epitopes contribute to type 1 diabetes susceptibility

Disease susceptibility for type 1 diabetes is strongly associated with the inheritance of specific HLA alleles. However, conventional allele frequency analysis can miss HLA associations because many alleles are rare. In addition, disparate alleles that have similar peptide-binding sites, or shared epitopes, can be missed. To identify the HLA shared epitopes associated with diabetes, we analyzed high-resolution genotyping for class I and class II loci. The HLA epitopes most strongly associated with susceptibility for disease were DQB1 A(57), DQA1 V(76), DRB1 H(13), and DRB1 K(71), whereas DPB1 YD(9,57), HLA-B C(67), and HLA-C YY(9,116) were more weakly associated. The HLA epitopes strongly associated with resistance were DQB1 D(57), DQA1 Y(80), DRB1 R(13), and DRB1 A(71). A dominant resistance phenotype was observed for individuals bearing a protective HLA epitope, even in the presence of a susceptibility epitope. In addition, an earlier age of disease onset correlated with significantly greater numbers of susceptibility epitopes and fewer resistance epitopes (P < 0.0001). The prevalence of both DQ and DR susceptibility epitopes was higher in patients than in control subjects and was not exclusively a result of linkage disequilibrium, suggesting that multiple HLA epitopes may work together to increase the risk of developing diabetes.

Relationship between Ljungan virus antibodies, HLA-DQ8, and insulin autoantibodies in newly diagnosed type 1 diabetes children

Environmental factors, including viral infections, may explain an increasing and fluctuating incidence of childhood type 1 diabetes (T1D). Ljungan virus (LV) isolated from bank voles have been implicated, but it is unclear whether LV contributes to islet autoimmunity, progression to clinical onset, or both, of T1D. The aim was to test whether LV antibodies (LVAb) were related to HLA-DQ and islet autoantibodies in newly diagnosed T1D patients (n=676) and controls (n=309). Patients, 0-18 years of age, diagnosed with T1D in 1996-2005 were analyzed for LVAb, HLA-DQ genotypes, and all seven known islet autoantibodies (GADA, IA-2A, IAA, ICA, ZnT8RA, ZnT8WA, and ZnT8QA). LVAb at 75(th) percentile, defined as cut off, was 90 (range 6-3936) U/mL and 4(th) quartile LVAb were found in 25% (170/676) of which 64% were <10 (n=108, p<0.0001), and 27% were<5 (n=45; p<0.0001) years old. The 4(th) quartile LVAb in children <10 years of age correlated to HLA DQ2/8, 8/8, and 8/X (p<0.0001). Furthermore, in the group with 4(th) quartile LVAb, 55% were IAA positive (p=0.01) and correlation was found between 4(th) quartile LVAb and IAA in children <10 years of age (p=0.035). It is concluded that 1) LVAb were common among the young T1D patients and LVAb levels were higher in the younger age groups; 2) 4(th) quartile LVAb correlated with IAA; and 3) there was a correlation between 4(th) quartile LVAb and HLA-DQ8, particularly in the young patients. The presence of LVAb supports the notion that prior exposure to LV may be associated with T1D.

Immunobiology of beta-cell destruction

Type 1 diabetes is a chronic disease characterized by severe insulin deficiency and hyperglycemia, due to autoimmune destruction of pancreatic islets of Langerhans. A susceptible genetic background is necessary, but not sufficient, for the development of the disease. Epidemiological and clinical observations underscore the importance of environmental factors as triggers of type 1 diabetes, currently under investigation. Islet-specific autoantibodies precede clinical onset by months to years and are established tools for risk prediction, yet minor players in the pathogenesis of the disease. Many efforts have been made to elucidate disease-relevant defects in the key immune effectors of islet destruction, from the early failure of specific tolerance to the vicious circle of destructive insulitis. However, the events triggering islet autoimmunity as well as the transition to overt diabetes are still largely unknown, making prevention and treatment strategies still a challenge.

The DQB1 *03:02 HLA haplotype is associated with increased risk of chronic pain after inguinal hernia surgery and lumbar disc herniation

Neuropathic pain conditions are common after nerve injuries and are suggested to be regulated in part by genetic factors. We have previously demonstrated a strong genetic influence of the rat major histocompatibility complex on development of neuropathic pain behavior after peripheral nerve injury. In order to study if the corresponding human leukocyte antigen complex (HLA) also influences susceptibility to pain, we performed an association study in patients that had undergone surgery for inguinal hernia (n=189). One group had developed a chronic pain state following the surgical procedure, while the control group had undergone the same type of operation, without any persistent pain. HLA DRB1genotyping revealed a significantly increased proportion of patients in the pain group carrying DRB1*04 compared to patients in the pain-free group. Additional typing of the DQB1 gene further strengthened the association; carriers of the DQB1*03:02 allele together with DRB1*04 displayed an increased risk of postsurgery pain with an odds risk of 3.16 (1.61-6.22) compared to noncarriers. This finding was subsequently replicated in the clinical material of patients with lumbar disc herniation (n=258), where carriers of the DQB1*03:02 allele displayed a slower recovery and increased pain. In conclusion, we here for the first time demonstrate that there is an HLA-dependent risk of developing pain after surgery or lumbar disc herniation; mediated by the DRB1*04 - DQB1*03:02 haplotype. Further experimental and clinical studies are needed to fine-map the HLA effect and to address underlying mechanisms.

Age-dependent variation of genotypes in MHC II transactivator gene (CIITA) in controls and association to type 1 diabetes

The major histocompatibility complex class II transactivator (CIITA) gene (16p13) has been reported to associate with susceptibility to multiple sclerosis, rheumatoid arthritis and myocardial infarction, recently also to celiac disease at genome-wide level. However, attempts to replicate association have been inconclusive. Previously, we have observed linkage to the CIITA region in Scandinavian type 1 diabetes (T1D) families. Here we analyze five Swedish T1D cohorts and a combined control material from previous studies of CIITA. We investigate how the genotype distribution within the CIITA gene varies depending on age, and the association to T1D. Unexpectedly, we find a significant difference in the genotype distribution for markers in CIITA (rs11074932, P=4 × 10(-5) and rs3087456, P=0.05) with respect to age, in the collected control material. This observation is replicated in an independent cohort material of about 2000 individuals (P=0.006, P=0.007). We also detect association to T1D for both markers, rs11074932 (P=0.004) and rs3087456 (P=0.001), after adjusting for age at sampling. The association remains independent of the adjacent T1D risk gene CLEC16A. Our results indicate an age-dependent variation in CIITA allele frequencies, a finding of relevance for the contrasting outcomes of previously published association studies.

Acculturation and celiac disease risk in second-generation immigrants: a nationwide cohort study in Sweden

OBJECTIVES

The burden of celiac disease (CD) is increasingly recognized as a global problem. However, whether this situation depends on genetics or environmental factors is uncertain. The authors examined these aspects in Sweden, a country in which the risk of CD is generally considered to be high. If environmental factors are relevant, CD risk in second-generation immigrant children should be related to maternal length of stay in Sweden before delivery.

MATERIAL AND METHODS

Linking the Swedish Medical Birth Registry to other national registries, the authors investigated all singleton children (n = 792,401) born in Sweden between 1987 and 1993. They studied the risk of CD in children before age 6 as a function of the mother's geographical region of birth and length of stay in Sweden before delivery using Cox regression models.

RESULTS

In children whose mothers immigrated to Sweden from a country outside of Europe, a maternal length of stay in Sweden of more than 5 years increased the hazard ratio (HR) of CD (1.73, 95% confidence interval (CI) 1.06-2.81). The authors observed a similar result among children born to mothers from a Nordic country outside of Sweden (HR 1.57, 95% CI 0.89-2.75), but a non-conclusive protective effect was observed in second-generation immigrant children from a non-Nordic European country (HR 0.65, 95% CI 0.39-1.09).

CONCLUSIONS

The risk of CD among second-generation immigrants seems to be conditioned by maternal length of stay in Sweden before delivery, suggesting that environmental factors contribute to the variation in CD risk observed across populations.

Coeliac disease in children: a social epidemiological study in Sweden

AIM

Little is known on the possible existence of socioeconomic and geographical differences in early coeliac disease (CD) risk. Therefore, we investigated these aspects in children before age two.

METHODS

Linking the Swedish Medical Birth Registry to several other national registries, we identified all singletons born in Sweden from 1987 to 1993 (n = 792,401) and followed them until 2 years of age to identify cases of CD. Applying multilevel logistic regression analysis, we investigated the association between socioeconomic position (SEP) and CD in children and also whether a possible geographical variation in CD risk was explained by individual characteristics.

RESULTS

Low SEP was associated with CD in boys OR 1.37 (95% CI 1.03-1.82), but not in girls OR 0.87 (95% CI 0.68-1.12). We found a considerable geographical variation in disease risk (i.e. intra-municipality correlation ≈ 10%) that was not explained by individual characteristics.

CONCLUSIONS

Low SEP is associated with CD in boys but not in girls. Also, CD appears to be conditioned by geographical area of residence. While our study represents an innovative contribution to the epidemiology of CD in children, the reasons for the observed geographical and socioeconomic differences could be speculated but are still unknown.

The Environmental Determinants of Diabetes in the Young (TEDDY): genetic criteria and international diabetes risk screening of 421 000 infants

AIMS

The Environmental Determinants of Diabetes in the Young (TEDDY) study seeks to identify environmental factors influencing the development of type 1 diabetes (T1D) using intensive follow-up of children at elevated genetic risk. This study requires a cost-effective yet accurate screening strategy to identify the high-risk cohort.

METHODS

The TEDDY cohort was identified through newborn screening using human leukocyte antigen (HLA) class II genes based on criteria established with pre-TEDDY data. HLA typing was completed at six international centers using different genotyping methods that can achieve >98% accuracy.

RESULTS

TEDDY developed separate inclusion criteria for the general population (GP) and first-degree relatives (FDRs) of T1D patients. The FDR eligibility includes nine haplogenotypes (DR3/4, DR4/4, DR4/8, DR3/3, DR4/4b, DR4/1, DR4/13, DR4/9, and DR3/9) for broad HLA diversity, whereas the GP eligibility includes only the first four haplogenotypes with DRB1*0403 as an exclusion allele. TEDDY has screened 414 714 GP infants, of which 19 906 (4.8%) were eligible, whereas 1415 of the 6333 screened FDR infants (22.2%) were eligible. High-resolution confirmation testing of the eligible subjects indicated that the low-cost and low-resolution genotyping techniques employed at the screening centers yielded an accuracy of 99%. There were considerable variations in eligibility rates among the centers for GP (3.5-7.4%) and FDR (19-32%) subjects. The eligibility rates among US ethnic groups were 0.9, 1.3, 5.0, and 6.9% for Asians, Black, Caucasians, and Hispanics, respectively.

CONCLUSIONS

Different low-cost and low-resolution genotyping methods are useful for the efficient and accurate identification of a high-risk cohort for follow-up based on the TEDDY HLA inclusion criteria.

Low risk HLA-DQ and increased body mass index in newly diagnosed type 1 diabetes children in the Better Diabetes Diagnosis study in Sweden

Objective

Type 1 diabetes and obesity has increased in childhood. We therefore tested the hypothesis that type 1 diabetes HLA-DQ risk genotypes may be associated with an increased body mass index (BMI).

Design

The type 1 diabetes high risk HLA-DQ A1*05:01-B1*02:01/A1*03:01-B1*03:02 genotype along with lower risk DQ genotypes were determined at the time of clinical onset by PCR and hybridization with allele-specific probes. Body mass index was determined after diabetes was stabilized.

Subjects

A total of 2403 incident type 1 diabetes children below 18 years of age were ascertained in the Swedish national Better Diabetes Diagnosis (BDD) studybetween May 2005 to September 2009. All children classified with type 1 diabetes including positivity for at least one islet autoantibody were investigated.

Results

Overall, type 1 diabetes HLA-DQ risk was negatively associated with BMI (p<0.0008). The proportion of the highest risk A1*05:01-B1*02:01/A1*03:01-B1*03:02 genotype decreased with increasing BMI (p<0.0004). However, lower risk type 1 diabetes DQ genotypes were associated with an increased proportion of patients who were overweight or obese (p<0.0001). Indeed, the proportion of patients with the low risk A1*05:01-B1*02:01/A1*05:01-B1*02:01 genotype increased with increasing body mass index (p<0.003). The magnitude of association on the multiplicative scale between the A1*05:01-B1*02:01/A1*05:01-B1*02:01 genotype and increased body mass index was significant (p<0.006). The odds ratio in patients with this genotype of being obese was 1.80 (95% CI 1.21–2.61; p<0.006). The increased proportion of overweight type 1 diabetes children with the A1*05:01-B1*02:01 haplotype was most pronounced in children diagnosed between 5 and 9 years of age.

Conclusions

Susceptibility for childhood type 1 diabetes was unexpectedly found to be associated with the A1*05:01-B1*02:01/A1*05:01-B1*02:01 genotype and an increased BMI. These results support the hypothesis that overweight may contribute to the risk of type 1 diabetes in children positive for HLA-DQ A1*05:01-B1*02:01.

Type 1 diabetes patients born to immigrants to Sweden increase their native diabetes risk and differ from Swedish patients in HLA types and islet autoantibodies

AIM

To determine whether type 1 diabetes mellitus (T1DM) patients, having parents who immigrated to Sweden, have increased T1DM risk before 18 yr compared with countries of origin. We also determined whether they have different human leukocyte antigen (HLA) genetic markers and islet autoantibodies at diagnosis compared with Swedish patients.

METHODS

A total of 1988 (53% males) newly diagnosed and confirmed T1DM patients <18 yr registered within the Better Diabetes Diagnosis (BDD) study (May 2005 to September 2008) were included. Participants were classified into three groups: Swedish, non-Swedish, and Mixed-origin patients according to country of origin of two generations (parents and grandparents). These groups were compared with respect to T1DM HLA markers and islet autoantibodies [glutamic acid decarboxylase autoantibodies (GAD65Ab), insulin autoantibodies (IAA), and islet antigen-2 autoantibodies (IA-2Ab)].

RESULTS

Only 30 (1.5%) patients were born outside Sweden. Swedish patients constituted 66%, non-Swedish patients 8%, Mixed origins 17%, and 9% were of uncertain origin. Confirmed T1DM in patients within the study was 22 (95% CI: 21-23) patients/10(5)/yr rate for Swedish patients compared with 14 (95% CI: 13-15) among non-Swedish patients. The HLA-DQ8 haplotype (p < 0.0001) and DQ2/8 genotype (p < 0.02) predominated among Swedish compared with non-Swedish patients. In contrast, DQ2 was the most frequent haplotype among non-Swedish patients [OR = 1.5 (95% CI: 1.0-2.0), p < 0.04]. Multiple (≥2) autoantibodies (p < 0.04) and specifically IA-2Ab (p < 0.001) were most prevalent among the Swedish patients. Multiple autoantibodies were associated with DQ8 among the Swedish patients only (p < 0.001).

CONCLUSION

Patients born to parents who had immigrated to the high T1DM incidence environment of Sweden have, compared with Swedish patients, more frequent HLA-DQ2 genetic markers and are diagnosed more often with GAD65Ab.

The association between the PTPN22 1858C>T variant and type 1 diabetes depends on HLA risk and GAD65 autoantibodies

The single nucleotide polymorphism 1858C>T in the PTPN22 gene is associated with type 1 diabetes (T1D) in several populations. Earlier reports have suggested that the association may be modified by human leukocyte antigen (HLA), as well as by islet autoantibodies. In a large case-control study of Swedish incident T1D patients and controls, 0-34 years of age, we tested whether the odds ratio (OR) measure of association was dependent on HLA or autoantibodies against the islet autoantigens glutamic acid decarboxylase 65 kDa autoantibodies (GADA), insulin, islet antigen-2, or islet cell. The association between the carrier status of 1858C>T allele in PTPN22 (PTPN22(CT+TT)) and T1D was modified by HLA. In addition, in GADA-positive T1D, the OR was 2.83 (2.00, 3.99), whereas in GADA-negative T1D, the OR was 1.41 (0.98, 2.04) (P for comparison=0.007). The OR of association between PTPN22(CT+TT) and GADA-positive T1D declined with increasing HLA-risk category from 6.12 to 1.54 (P=0.003); no such change was detected in GADA-negative T1D (P=0.722) (P for comparison=0.001). However, the absolute difference in risk between PTPN22(CC) and PTPN22(CT+TT) subjects with high-risk HLA was five times higher than that for subjects with low-risk HLA. We hypothesize that the altered T-cell function because of the PTPN22(1858C>T) polymorphism is exclusively associated with GADA-positive T1D at diagnosis.

Autoimmune type 1 diabetes genetic susceptibility encoded by human leukocyte antigen DRB1 and DQB1 genes in Tunisia

Human leukocyte antigen (HLA) class II genes contribute to the genetic susceptibility to type 1 diabetes (T1D), and susceptible alleles and haplotypes were implicated in the pathogenesis of T1D. This study investigated the heterogeneity in HLA class II haplotype distribution among Tunisian patients with T1D. This was a retrospective case control study done in Monastir in central Tunisia. The subjects comprised 88 T1D patients and 112 healthy controls. HLA-DRB1 and -DQB1 genotyping was done by PCR-sequence-specific priming. Significant DRB1 and DQB1 allelic differences were seen between T1D patients and controls; these differences comprised DRB1*030101 and DQB1*0302, which were higher in T1D patients than in control subjects, and DRB1*070101, DRB1*110101, DQB1*030101, and DQB1*060101, which were lower in T1D patients than in control subjects. In addition, the frequencies of DRB1*030101-DQB1*0201 and DRB1*040101-DQB1*0302 were higher in T1D patients than in control subjects, and the frequencies of DRB1*070101-DQB1*0201 and DRB1*110101-DQB1*030101 haplotypes were lower in T1D patients than in control subjects. Multiple logistic regression analysis revealed the positive association of DRB1*030101-DQB1*0201 and DRB1*040101-DQB1*0302 and the negative association of only DRB1*070101-DQB1*0201 haplotypes with T1D. Furthermore, a significantly increased prevalence of DRB1*030101-DQB1*0201 homozygotes was seen for T1D subjects than for control subjects. Our results confirm the association of specific HLA-DR and -DQ alleles and haplotypes with T1D in Tunisians. The identification of similar and unique haplotypes in Tunisians compared to other Caucasians highlights the need for evaluating the contribution of HLA class II to the genetic susceptibility to T1D with regard to haplotype usage and also to ethnic origin and racial background.

Risk conferred by HLA-DR and DQ for type 1 diabetes in 0-35-year age group in Sweden

HLA DR4-DQ8 and DR3-DQ2 haplotypes account for 89% of newly diagnosed cases of type 1 diabetes (T1D) in Sweden. The presence of a single copy of DQ6 confers protection. The aim of the present study is to evaluate whether the risk conferred by high risk HLA DR and DQ to T1D is similar in all regions of Sweden and see whether there are any significant regional differences. The subjects comprised 799 consecutively diagnosed T1D patients and 585 age-, sex-, and geography-matched healthy controls in the age group 0-35 years. HLA typing for high-risk haplotypes was previously performed using PCR-SSOP and RFLP. The results showed that HLA DR3-DR4 gave an odds ratio of 8.14 for the whole of Sweden. However, when the study group was divided into six geographical regions, subjects from Stockholm had the highest OR, followed by those from Lund, Linköping, Gothenburg, Umeå, and Uppsala. Absolute protection was conferred by the presence of DQ6 in subjects from the Linköping region, but varied in the other regions. The frequency of DR3 and DQ2, DR4 and DQ8, DR15, and DQ6 in patients showed high linkage for each region, but were different between regions.

IN CONCLUSION

The risk conferred by high-risk HLA varies in different regions for a homogenous population in Sweden. The results highlight the important role played by the various environmental factors in the precipitation of T1D.

The Co-operative Specificity Theory: phenotypic protection from T1D by certain HLA Class II DRB1 and DQ alleles identifies the absence of co-operation between the respective DR and DQ molecules eventuating in no T1D-predisposition

It is well established that both DR and DQ genes are involved in type 1 diabetes (T1D) -susceptibility. But how the DR and DQ molecules contrive to effect collectively the same function of T1D predisposition remains unexplained. We advance the Co-operative Specificity Theory which attempts to project the relationship by which this occurs. The Co-operative Specificity Theory says that what is involved and being observed is a phenomenon of specific reciprocal recognition between corresponding DR- and DQ-molecules in a haplotype, resulting in a co-operation that realizes effects: this specificity varies in degrees. It is a situation of co-operative participation restricted to a specific DR- and its corresponding specific DQ-molecules that results in susceptibility. Thus susceptibility may not result when a corresponding specific DR or DQ allele is substituted by a non-specific allele in the haplotype. It thus ensues that phenotypic protection identifies the absence of this specific co-operation between the respective DR and DQ molecules giving rise to no predisposition.

Temporal trends of HLA genotype frequencies of type 1 diabetes patients in Sweden from 1986 to 2005 suggest altered risk

The aim of this study was to compare the frequency of human leukocyte antigen (HLA) genotypes in 1-18-year-old patients with type 1 diabetes newly diagnosed in 1986-1987 (n = 430), 1996-2000 (n = 342) and in 2003-2005 (n = 171). We tested the hypothesis that the HLA DQ genotype distribution changes over time. Swedish type 1 diabetes patients and controls were typed for HLA using polymerase chain reaction amplification and allele specific probes for DQ A1* and B1* alleles. The most common type 1 diabetes HLA DQA1*-B1*genotype 0501-0201/0301-0302 was 36% (153/430) in 1986-1987 and 37% (127/342) in 1996-2000, but decreased to 19% (33/171) in 2003-2005 (P \ 0.0001). The 0501-0201/0501-0201 genotype increased from 1% in 1986-1987 to 7% in 1996-2000 (P = 0.0047) and to 5% in 2003-2005 (P > 0.05). This study in 1-18-year-old Swedish type 1 diabetes patients supports the notion that there is a temporal change in HLA risk.

Influence of common and specific HLA-DRB1/DQB1 haplotypes on genetic susceptibilities of three distinct Arab populations to type 1 diabetes

The contribution of HLA DRB-DQB to type 1 diabetes (T1D) in Bahrainis, Lebanese, and Tunisians was investigated. DRB1*030101-DQB1*0201 was a locus that conferred susceptibility in three populations, while DRB1*040101-DQB1*0302 was a locus that conferred susceptibility only in Tunisians and Bahrainis. The DRB1*100101-DQB1*050101 (Bahrainis) and DRB1*150101-DQB1*060101 (Lebanese) loci were largely protective. The contribution of HLA to T1D must be evaluated with regard to ethnic background.

Number of islet autoantibodies present in newly diagnosed type 1 diabetes children born to non-diabetic mothers is affected by islet autoantibodies present at birth

OBJECTIVE

Cord blood islet autoantibodies in children born to mothers with type 1 diabetes may be associated with a reduced risk of islet autoimmunity and diabetes. The aim of this study was to investigate in children with type 1 diabetes but born to non-diabetic mothers whether islet autoantibodies at birth affected their presence at diagnosis.

PATIENTS AND METHODS

Serum samples at birth and at diagnosis were available from 141 children who developed type 1 diabetes between 1 and 19 yr of age (median 9.0 yr; male/female ratio 83/58). The samples were tested for autoantibodies against glutamic acid decarboxylase, insulinoma-associated antigen 2, and insulin as well as for islet cell antibodies. The human leukocyte antigen genotype was also determined.

RESULTS

The frequency of islet autoantibodies in the umbilical cord blood was 11% compared with 91% at diagnosis. Children with fewer islet autoantibodies at diagnosis were more likely to have had autoantibodies at birth (p = 0.02). Autoantibodies present in cord blood at birth were observed in 25% (3/12) of children with no islet autoantibodies at diagnosis, in 17% (7/42) of children with one or two antibodies at diagnosis, and in only 5% (4/86) of children with more than two antibodies, demonstrating an inverse relationship between autoantibodies at birth and at diagnosis (test for trend, p < 0.001).

CONCLUSIONS

Our preliminary data suggest that exposure to cord blood islet autoantibodies may influence the presence of islet autoantibodies at the time of diagnosis of type 1 diabetes and explain why some type 1 diabetes children are islet autoantibody negative at clinical diagnosis.

Modulation of type 1 diabetes susceptibility by tumor necrosis factor alpha -308 G/A and lymphotoxin alpha +249 A/G haplotypes and lack of linkage disequilibrium with predisposing DQB1-DRB1 haplotypes in Bahraini patients

Tumor necrosis factor alpha (TNF-alpha) -308 G/A and lymphotoxin alpha (LTalpha) +249 A/G single-nucleotide polymorphisms were investigated in 228 type 1 diabetes mellitus (T1DM) patients and 240 controls. Only LTalpha +249G allele and +249G/+249G genotype frequencies were higher among patients, and no linkage disequilibrium was found between TNF-alpha/LTalpha alleles and susceptible/protective DRB1-DQB1 haplotypes. TNF-alpha/LTalpha T1DM-susceptible (-308G/+249G) and protective (-308G/+249A) haplotypes were identified.

IA-2 autoantibodies in incident type I diabetes patients are associated with a polyadenylation signal polymorphism in GIMAP5

In a large case-control study of Swedish incident type I diabetes patients and controls, 0-34 years of age, we tested the hypothesis that the GIMAP5 gene, a key genetic factor for lymphopenia in spontaneous BioBreeding rat diabetes, is associated with type I diabetes; with islet autoantibodies in incident type I diabetes patients or with age at clinical onset in incident type I diabetes patients. Initial scans of allelic association were followed by more detailed logistic regression modeling that adjusted for known type I diabetes risk factors and potential confounding variables. The single nucleotide polymorphism (SNP) rs6598, located in a polyadenylation signal of GIMAP5, was associated with the presence of significant levels of IA-2 autoantibodies in the type I diabetes patients. Patients with the minor allele A of rs6598 had an increased prevalence of IA-2 autoantibody levels compared to patients without the minor allele (OR=2.2; Bonferroni-corrected P=0.003), after adjusting for age at clinical onset (P=8.0 x 10(-13)) and the numbers of HLA-DQ A1*0501-B1*0201 haplotypes (P=2.4 x 10(-5)) and DQ A1*0301-B1*0302 haplotypes (P=0.002). GIMAP5 polymorphism was not associated with type I diabetes or with GAD65 or insulin autoantibodies, ICA, or age at clinical onset in patients. These data suggest that the GIMAP5 gene is associated with islet autoimmunity in type I diabetes and add to recent findings implicating the same SNP in another autoimmune disease.

MHC Class I Chain-Related Gene-A Is Associated with IA2 and IAA but Not GAD in Swedish Type 1 Diabetes Mellitus

In type 1 diabetes mellitus (T1DM), the frequency of antibodies against insulin (IAA), glutamic acid decarboxylase-65 (GAD65), ICA512/IA2 (IA2), and islet cell antigens (ICA) vary with human leukocyte antigen (HLA) composition of the patient. IAA, IA2 autoantibodies, and ICA are increased in DQ8 positives; GAD65 antibodies are increased in DQ2 positives. MHC class I chain-related gene-A (MICA) is another genetic marker that has been proposed to be associated with T1DM. In this article, we looked at microsatellite polymorphism of MICA and its association with autoantibodies (IAA, IA2, and GAD65) in Swedish T1DM patients and if the association explains its importance in early events in autoimmune response. We studied 635 T1DM patients between 0-35 years. Frequency of MICA5/5 was positively associated with the formation of IAA and IA2 antibodies considered individually or in combination (odds ratio [OR], 95% CI, Pc: [IAA+ versus IAA-]: 4.94, 2.09-11.62, <0.0005; [IA2+ versus IA2-]: 2.65, 1.52-4.59, 0.0015; [IAA and/or IA2+ versus rest]: 9.83, 2.37-40.78, <0.0015; [IAA and IA2+ versus rest]: 3.51, 2.01-6.15, <0.0015). Also, -5.1/5.1 was increased in IAA+ patients compared to IAA- patients (2.82, 1.64-4.83, <0.0005). All patients positive for -5/5 developed at least one of the three antibodies. Frequency of MICA5.1 was decreased in IAA+ (0.54, 0.36-0.81, 0.017), in IA2A+ (0.63, 0.45-0.88, 0.04), in IAA and/or IA2A+ (0.52, 0.33-0.84, 0.044), and in IAA and IA2A+ (0.55, 0.39-0.78, 0.0055) patients when compared with patients negative for corresponding antibodies. Frequency of MICA9, 5/5.1, and 5.1/9 was decreased in IAA+ compared to IAA- patients (0.51, 0.32-0.79, 0.021; 0.22, 0.11-0.44, <0.005; and 0.39, 0.22-0.69, 0.026, respectively). Frequency of MICA9 and -5.1/9 was also decreased in IAA and/or IA2 antibody-positive patients while MICA5/5.1 decreased in patients positive for IAA and IA2 antibody both together. IAA and IA2 antibodies are believed to appear early during the autoimmune reaction against beta cells. Thus, according to our data, MICA-5/5 and -5.1/5.1 is associated with early autoimmunity in T1DM patients. Our study suggests that MICA gene polymorphism is associated with autoantibody formation and that the polymorphism especially MICA5/5 and -5.1/5.1 are important in early events of autoimmune reaction.

Genes Influencing Innate and Acquired Immunity in Type 1 Diabetes and Latent Autoimmune Diabetes in Adults

DQ8 and DQ2 are associated with susceptibility to and DQ6 with protection from type 1 diabetes mellitus (T1DM). A set of polymorphic genes, called MHC class I chain-related genes (MIC-A) in HLA class I region interact with NK cells. In Italians, MICA allele 5 increases T1DM risk by 6.1. Together with HLA-DQ8 and DQ2 the risk increases severalfold. HLA class I genes, also identified as susceptibility genes for T1DM, interact with polymorphic killer immunoglobulin-like receptors (KIR) on NK cells. HLA-DQ8 and DQ2 and MICA-5 in Swedish and other populations also show positive association with disease. Studies on KIR in Latvian patients with T1DM also suggest a role for KIR in the etiology of T1DM. The results from MICA and KIR studies suggest that polymorphism of these genes of the innate immune system identify possible defects in the first line of antiviral defense in the etiology of T1DM. Screening for these genes could be important in the prediction strategies for T1DM.

Genetic analysis of families with autoimmune diabetes and thyroiditis: evidence for common and unique genes

CONTEXT

Epidemiological data suggest a common genetic susceptibility to type 1 diabetes (T1D) and autoimmune thyroid disease (AITD).

OBJECTIVE

Our objective was to identify the joint susceptibility genes for T1D and AITD.

DESIGN

We conducted a family-based linkage and association study.

SETTING

The study took place at an academic medical center.

PARTICIPANTS

Participants included 55 multiplex families (290 individuals) in which T1D and AITD clustered (T1D-AITD families).

MAIN OUTCOME MEASURES

We conducted tests for linkage and family-based associations (transmission disequilibrium test) with four candidate genes: human leukocyte antigen (HLA), cytotoxic T lymphocyte-associated antigen 4 (CTLA-4), insulin variable number of tandem repeats (VNTR), and thyroglobulin.

RESULTS

Linkage evidence to HLA appeared when subjects with either T1D or AITD were considered affected [maximum LOD score (MLS), 2.2]. The major HLA haplotype contributing to the shared susceptibility was DR3-DQB1*0201, with DR3 conferring most of the shared risk. The CTLA-4 gene showed evidence for linkage only when individuals with both T1D and AITD were considered affected (MLS, 1.7), and the insulin VNTR showed evidence for linkage when individuals with either T1D or AITD were considered affected (MLS, 1.9); i.e. it may contribute to the familial aggregation of T1D and AITD.

CONCLUSIONS

The HLA class II locus contributes to the shared risk for T1D and AITD, and the major HLA haplotype contributing to this association is DR3-DQB1*0201. Additional non-HLA loci contribute to the joint susceptibility to T1D and AITD, and two potential candidates include the CTLA-4 and insulin VNTR loci.

HLA-DR-DQ haplotypes and genotypes in Finnish patients with rheumatoid arthritis

OBJECTIVES

To elucidate the contribution of HLA-DR-DQ haplotypes and their genotypic combinations to susceptibility to rheumatoid arthritis, and to evaluate the various models for HLA associated risk for the disease in a series of Finnish patients.

METHODS

322 Finnish patients with rheumatoid arthritis were typed for common north European HLA-DR-DQ haplotypes and compared with a series of 1244 artificial family based control haplotypes.

RESULTS

The association of the so called shared epitope (SE) haplotypes (DRB1*0401, *0404, *0408, and *01) with rheumatoid arthritis was confirmed. The DRB1*0401 haplotypes carried a far stronger risk for the disease than the (DRB1*01/10)-(DQA1*01)-DQB1*0501 haplotypes. Seven protective HLA haplotypes--(DRB1*15)-(DQA1*01)-DQB1*0602; (DRB1*08)-(DQA1*04)-DQB1*04; (DRB1*11/12)-DQA1*05-DQB1*0301; (DRB1*1301)-(DQA1*01)-DQB1*0603; (DRB1*1302)-(DQA1*01)-DQB1*0604; (DRB1*07)-DQA1*0201-DQB1*0303; and (DRB1*16)- (DQA1*01)-DQB1*0502--were identified. In accordance with the reshaped shared epitope hypothesis, all the protective DRB1 alleles in these haplotypes share either isoleucine at position 67 or aspartic acid at position 70 in their third hypervariable region motif. However, differences in the disease risk of haplotypes carrying the same DR but different DQ alleles were also found: (DRB1*07)-DQA1*0201-DQB1*0303 was protective, while (DRB1*07)-DQA1*0201-DQB1*02 was neutral. The same haplotypes carried different risks for rheumatoid arthritis depending on their combination in genotypes.

CONCLUSIONS

When assessing the influence of HLA genes on the susceptibility to rheumatoid arthritis, not only should the HLA-DR or -DQ alleles or haplotypes be unravelled but also the genotype. The effect of HLA class II region genes is more complicated than any of the existing hypotheses can explain.

Frequency of MICA in All Babies in Southeast Sweden (ABIS) Positive for High-Risk HLA-DQ Associated with Type 1 Diabetes

Type 1 diabetes mellitus (T1DM) is an autoimmune disease known to occur in genetically susceptible individuals after exposure to certain unknown environmental factors. HLA-DR3-DQ2 or DR4-DQ8 are established genetic markers for the disease. MHC class I chain-related gene-A (MICA) gene polymorphism has been proposed to be associated with T1DM. To identify the environmental factors and for implementing intervention trials to prevent T1DM, it is important to screen subjects at genetically increased risk for developing T1DM. The All Babies in Southeast Sweden (ABIS) study aims to assess the risk of future progression to T1DM in the general child population. In the present report, we studied the frequency of MICA alleles among newborn babies carrying high-risk HLA DQ2 or DQ8. Of 2821 newborns, we found 563 subjects positive for DQ2, 583 subjects positive for DQ8, 133 subjects positive for DQ2-DQ8 (heterozygous), and 1013 subjects positive for either DQ2 or DQ8. Of these 1013 babies, we typed 499 babies for MICA. Frequency of MICA5 was 38% among DQ8+, 35% among for DQ2-DQ8 (heterozygous) positives, and 22.5% among DQ2+ babies. Frequency of MICA5.1 was 81% among DQ+, 62% among DQ8+, and 71% among DQ2-DQ8 (heterozygous) positives. Frequency of MICA6 was between 20% and 22% among the three groups. Frequency of MICA5/5.1 was 19% among DQ2-DQ8 (heterozygous) positives and between 12% and 13% among those positive for DQ2, DQ8, DQ2, or DQ8. The results from genetic typing in this study would be useful, in conjunction with results from autoantibody analysis that are prospectively being followed-up in all the babies, to develop an approach for identifying children at risk for developing T1DM. Inclusion of MICA typing in addition to HLA could be useful for screening of genetic markers associated with T1DM.

Type 1 diabetes mellitus in childhood: a matched case control study in Lancashire and Cumbria, UK

AIMS

The aim of the study was to identify environmental risk factors for insulin-dependent diabetes mellitus (Type 1 DM) in childhood.

METHODS

A matched case-control study of Type 1 DM conducted in Lancashire and Cumbria, UK, using a structured interview. Cases (n=196, participation rate 83%) were children under 16 years of age diagnosed prior to October 1998 and attending diabetic clinics. Controls (n=381) were healthy children from the community matched by gender and by age (within a few days of birth). The data were analysed by logistic regression using the technique of Breslow and Day for matched case control studies.

RESULTS

The multivariate regression model showed that the following factors were significantly associated with the risk of developing Type 1 DM (odds ratio, 95% confidence intervals): sharing a room with a sibling (0.458, 0.290-0.721), social contact with other children when aged 6-11 months (0.439, 0.256-0.752), consumption of sugary food (0.080, 0.024-0.261), parental insulin dependent diabetes mellitus (10.651, 3.086-36.761), maternal thyroid disease (4.861, 1.681-14.058), consuming more than one pint of milk per day prior to school entry (0.498, 0.310-0.802), maternal smoking during pregnancy (0.373, 0.218-0.636), a father with no academic qualifications (0.504, 0.278-0.913), maternal age at time of birth (0.900, 0.854-0.948), maternal infections in pregnancy (2.453, 1.011-5.948), other maternal illnesses or conditions in pregnancy (2.007, 1.139-3.535), belonging to an Asian family (0.104, 0.028-0.394), and regular contact with pets and other animals (0.552, 0.309-0.987).

CONCLUSION

Many of the results are consistent with the hygiene hypothesis which links improved living standards with decreased exposure to microorganisms and increased risk of immune mediated disease in childhood. These findings challenge the idea that improved hygiene acts exclusively through a Th2 mechanism leading to atopic disease as Type 1 DM is mediated by a Th1 reaction. The association with maternal smoking could be due to recall bias but a causal link cannot be excluded with confidence.

Normal weight promotes remission and low number of islet antibodies prolong the duration of remission in Type 1 diabetes

AIM

To identify clinical, immunological and biochemical factors that predict remission, and its duration in a large cohort of young adults with Type 1 diabetes mellitus (DM).

METHODS

In Sweden, 362 patients (15-34 years), classified as Type 1 DM were included in a prospective, nation-wide population-based study. All patients were followed at local hospitals for examination of HbA(1c) and insulin dosage over a median period after diagnosis of 5 years. Duration of remission, defined as an insulin maintenance dose </= 0.3 U/kg/24 h and HbA(1c) within the normal range, was analysed in relation to characteristics at diagnosis.

RESULTS

Remissions were seen in 43% of the patients with a median duration of 8 months (range 1-73). Sixteen per cent had a remission with a duration > 12 months. Among patients with antibodies (ab(+)), bivariate analysis suggested that adult age, absence of low BMI, high plasma C-peptide concentrations, lack of ketonuria or ketoacidosis at diagnosis and low insulin dose at discharge from hospital were associated with a high possibility of achieving remission. Multiple regression showed that normal weight (BMI of 20-24.9 kg/m(2)) was the only factor that remained significant for the possibility of entering remission. In survival analysis among ab(+) remitters, a low number of islet antibodies, one or two instead of three or four, were associated with a long duration of remissions.

CONCLUSION

In islet antibody-positive Type 1 DM, normal body weight was the strongest factor for entering remission, whilst a low number of islet antibodies was of importance for the duration.

HLA class II typing in newborns reveals a low frequency of the DRB1*04 allele and a high frequency of DRB1*11 allele in three regions of continental Italy

As part of a longitudinal study aimed at defining the natural history of prediabetic autoimmunity and predicting the risk of future cases of type 1 diabetes, 3607 newborns from three regions of continental Italy (Lombardia, Liguria, and Lazio) were subjected to genetic testing to determine human leukocyte antigen-DRB1 (HLA-DRB1) and -DQB1 allele and phenotype frequencies. Polymerase chain reaction and immobilized sequence-specific oligonucleotide probe assays were used to identify ten DRB1 allele lineages and three DQB1 alleles. No major inter-regional differences emerged in the allelic distribution indicating homogeneous distribution of the HLA DRB1-DQB1 alleles among the three regions analyzed. Comparison of our data with those published for other Caucasian populations reveals that these three regions are characterized by a very low frequency of DRB1*04 (8%) and a high frequency of DRB1*11 (25%). The phenotype frequencies of HLA-DQB1*0302 and DQB1*0602 observed are also lower than those reported for other populations. Furthermore, the DRB1*04-DQB1*0302 haplotype was relatively infrequent in our population (5.3% of the newborns tested). These findings furnish a genetic "portrait" of the populations of the analyzed regions that will be useful not only for investigation of the genetic risk of type 1 diabetes mellitus in Italy but also for studies of other autoimmune diseases related to HLA genotypes.

Inheritance of MHC Class II Genes in Lithuanian Families with Type 1 Diabetes

Type 1 diabetes mellitus (DM) is caused by genetic and environmental factors. Twice as many fathers as mothers of children with type 1 DM have the disease. The reason for the differences remains unclear. We looked at the transmission rates of diabetes-related alleles from parents to children with diabetes. All children with newly diagnosed type 1 DM from August 1, 1996 to August 1, 2000, aged 0 to 15 years, in Lithuania were invited to participate. Blood samples for full genetic analysis were available from 125 families. HLA DQA1, DQB1, and DRB1 typing was done on DNA extracted from peripheral blood, by polymerase chain reaction amplification, manual dot-blotting onto nylon membranes, synthetic sequence-specific oligonucleotide probe 3'-end labeling with (32)P-dCTP, and hybridization, followed by stringency washes, autoradiography, and allele calling. Frequency of diabetes risk-related alleles DQB1*0302, DQA1*0201, DR4, and DR3 was less prevalent among Lithuanian than among Swedish children with type 1 DM. Transmission rates of DR4-DQB1*0302-DQA1*0301 and DR3-DQB1*0201-DQA1*0501 haplotypes from parents were higher than expected: chi(2) (TDT) 30.56, p < 0.0001, and chi(2) (TDT) 11.26, p = 0.0008, respectively. DQB1*0302 and DR4 were significantly more frequently transmitted from both parents, but DR3 was transmitted more frequently only from mothers. Any of these alleles had similar frequencies among female and male offspring. We conclude that, besides DR4-DQB1*0302-DQA1*0301 and DR3-DQB1*0201-DQA1*0501, there are other inherited alleles that determine risk for type 1 DM among children in Lithuania. Fathers might transfer other alleles of disease susceptibility in higher frequency or mothers might provide a protective environment during pregnancy, which results in higher risk to offspring of fathers than mothers to develop diabetes.

No evidence of type 1 diabetes susceptibility genes in the region centromeric of the HLA complex

There is strong evidence that DQB1, DQA1, and DRB1 alleles are not the only contributors to the human leukocyte antigen (HLA) linked type 1 diabetes (T1D) predisposition. Although the HLA complex is much studied for disease association, little is known about the neighboring centromeric region. We have previously found suggestive association on DQ2-DR3 haplotypes for marker D6S291, located 3.6-Mb centromeric of HLA-DQB1. This region on human chromosome 6 is syntenic to a part of the region adjacent to the mouse major histocompatibility complex (MHC) on chromosome 17, which has been suggested to harbor a susceptibility gene in mouse (Idd16). To evaluate a possible role of the region centromeric of HLA-DQB1 in human T1D, we have scanned the region with nine microsatellite markers in 267 T1D families from five different populations. Our results indicate that the characteristic strong linkage disequilibrium in the HLA complex does not extend into this region. Furthermore, we did not detect any consistent T1D association for the markers analyzed in the study. In conclusion, our data argue against the presence of any strong genetic susceptibility factors for T1D in the region centromeric of the HLA complex.

Coxsackie virus B antibodies are increased in HLA DR3-MICA5.1 positive type 1 diabetes patients in the Linköping region of Sweden

Type 1 diabetes mellitus (T1DM) is an autoimmune disorder in which genetics and environmental factors play a role. Among the environmental factors, viruses (especially Coxsackie virus B [CBV]), and among genetic markers, human leukocyte antigen (HLA) DRB1*04-DQA1*0301-DQB1*0302 (DR4-DQ8) and DRB1*03-DQA1*0501-DQB1*0201 (DR3-DQ2), and major histocompatibility complex class I chain-related gene-A (MICA) alleles 5 and 5.1 have been reported to be associated with T1DM in Caucasians. Sweden ranks third in the world for T1DM incidence. In Sweden, the Linköping region indicates the highest incidence for T1DM. In this study, we analyzed whether antibodies against CBV are increased in DR3, DR4, MICA5, or MICA5.1 positive patients from Linköping (n = 46) and from Swedish population as a whole (n = 298) between the age of 0 and 15 years old. There was no difference in the frequency of antibodies to CBV in patients compared with controls in Linköping (26% vs 23%) or in all of Sweden (26% vs 21%). However, CBV antibodies were increased in DR3, DR3-DR4 (heterozygous), DR3-MICA5.1, and DR3-DR4-MICA5.1 positive compared with DR3, DR3-DR4, DR3-MICA5.1, and DR3-DR4-MICA5.1 negative patients in Linköping (p < 0.05 for all), but not in Swedish population as a whole. Thus, our study suggests that in addition to DR3, MICA5.1 has an influence on the immune response to CBV infection in patients from Linköping.

HLA associations in type 1 diabetes: DPB1 alleles may act as markers of other HLA-complex susceptibility genes

Alleles at the HLA-DQB1, -DQA1 and -DRB1 loci are major determinants for susceptibility to develop type 1 diabetes (T1D). Increasing evidence supports that also other genes in, or near, the HLA complex contribute to the HLA-encoded risk. Alleles at the DPB1 locus have been suggested to directly influence the risk conferred by DQB1, DQA1 and DRB1 alleles, but the results are conflicting. We therefore genotyped 217 families from Norway, Denmark, Sweden and southern France to address the role of DPB1 alleles in T1D. After taking into account linkage disequilibrium (LD) with DQB1, DQA1 and DRB1 alleles, we found evidence that some DPB1 alleles are associated with modulating the risk of developing T1D. However, we show that the strong LD in the HLA complex, and the presence of extended haplotypes complicate the interpretation of the results. On DQ2-DR3 haplotypes, both allele 3 at microsatellite D6S2223 located 5.3-Mb telomeric of DPB1 and the extended DQ2-DR3-B18 haplotype display much stronger association than DPB1 alleles. When we exclude these effects, most of the apparent association of DPB1 alleles on DQ2-DR3 haplotypes disappear. Taken together, although we cannot completely rule out an effect of some DPB1 alleles, we propose that the statistically significant, albeit weak, DPB1 associations found are most likely the result of LD with another unidentified disease-susceptibility gene(s) in this region.

Association between the transmembrane region polymorphism of MHC class I chain related gene-A and type 1 diabetes mellitus in Sweden

Major histocompatibility complex (MHC) class I chain related gene-A (MIC-A) is associated with type 1 diabetes mellitus (T1DM) in other populations. We tested the association of MIC-A gene polymorphism with T1DM in Swedish Caucasians; if it has an age-dependent association; and if the association has an effect on gender. We studied 635 T1DM patients and 503 matched controls in the age group of 0-35 years old. MIC-A5 was significantly increased in T1DM compared with controls (odds ratio [OR] =1.81, p(c) < 0.0005). Logistic regression analysis revealed MIC-A5 association was independent of HLA. MIC-A5 with DR4-DQ8 or MIC-A5 with DR3-DQ2 gave higher OR than the OR obtained with either of them alone (OR = 1.81, 7.1, and 3.6, respectively). MIC-A5 was positively (OR = 2.48, p(c) < 0.0005) and MIC-A6 negatively associated (OR = 0.61, p(c) = 0.035) with the disease in < or = 20 years of age. The negative association of MIC-A6 in young onset was confirmed by logistic regression analysis. MIC-A5 was associated with the disease in males (OR = 2.05, p(c) = 0.0005). MIC-A6 conferred protection (OR = 0.098, p(c) = 0.032) in females heterozygous for DR3/DR4. In conclusion, MIC-A5 is associated with T1DM; the association was higher in individuals < or = 20 years old; and negative association of MIC-A6 was stronger in younger onset patients than in older onset patients.