Genetic susceptibility in type 1 diabetes and its associated autoimmune disorders

Celiac disease screening in children and adolescents with type 1 diabetes mellitus: What test should be performed?

INTRODUCTION

Children and adolescents with type 1 diabetes mellitus (T1DM) are at high risk for the development of celiac disease (CD) because of the common genetic characteristics of both conditions. The study objectives were to investigate the frequency of the human leukocyte antigen system (HLA) for CD in pediatric T1DM patients and to determine whether HLA testing is suitable for CD screening in that population and is cost-effective as compared to serological screening for CD.

PATIENTS AND METHODS

A retrospective, descriptive study was conducted in 296 patients (148 girls; 148 boys) with T1DM aged <18 years who attended a Madrid hospital. Data on the frequency of genotypes DQ2/DQ8 in a subgroup of 92 patients and the additional cost of performing HLA typing for screening CD were collected. Only when the risk HLA haplotype (DQ2/DQ8) is negative no further serological screening for CD is required.

RESULTS

Twenty-three patients with T1DM (7.77%) also had CD. Alleles DQ2 or DQ8 were found in 91.3% of patients in whom the HLA haplotype was studied. Thus, only 8.7% with a negative haplotype would have benefited from HLA testing. The additional cost of HLA typing was € 105.2 for each patient with positive DQ2 or DQ8 in our population.

CONCLUSIONS

HLA typing is not a cost-effective screening method for CD in T1DM because of the frequent association of T1DM with risk genotypes for CD.

Collective effects of common single nucleotide polymorphisms and genetic risk prediction in type 1 diabetes

Type 1 diabetes (T1D) is a common autoimmune disease and may be related to multiple genetic and environmental risk factors. Previous genetic studies have focused on looking for individual polymorphic risk variants. Here, we studied the overall levels of genetic diversity in T1D patients by making use of a previously published study including 1865 cases and 2828 reference samples with genotyping data for 500 K common single nucleotide polymorphisms (SNPs). We determined the minor allele (MA) status of each SNP in the reference samples and calculated the total number of MAs or minor allele contents (MAC) of each individual. We found the average MAC of cases to be greater than that of the reference samples. By focusing on MAs with strong linkage to cases, we further identified a set of 112 SNPs that could predict 19.19% of cases. These results suggest that overall genetic variation over a threshold level may be a risk factor in T1D and provide a new genetic method for predicting the disorder.

Prevalence of celiac disease in patients with severe food allergy

The association between food allergy and celiac disease (CD) is still to be clarified. We screened for CD 319 patients with severe food allergy (IgE > 85 kU/l against food proteins and a history of severe allergic reactions) who underwent specific food oral immunotherapy (OIT), together with 128 children with mild allergy who recovered without OIT, and compared the prevalence data with our historical data regarding healthy schoolchildren. Sixteen patients (5%) with severe allergy and one (0.8%) with mild allergy tested positive for both genetic and serological CD markers, while the prevalence among the schoolchildren was 1%. Intestinal biopsies were obtained in 13/16 patients with severe allergy and in the one with mild allergy, confirming the diagnosis of CD. Sufferers from severe food allergy seem to be at a fivefold increased risk of CD. Our findings suggest that routine screening for CD should be recommended in patients with severe food allergy.

Assessment of CD4+ T cell responses to glutamic acid decarboxylase 65 using DQ8 tetramers reveals a pathogenic role of GAD65 121-140 and GAD65 250-266 in T1D development

Susceptibility to type 1 diabetes (T1D) is strongly associated with MHC class II molecules, particularly HLA-DQ8 (DQ8: DQA1*03:01/DQB1*03:02). Monitoring T1D-specific T cell responses to DQ8-restricted epitopes may be key to understanding the immunopathology of the disease. In this study, we examined DQ8-restricted T cell responses to glutamic acid decarboxylase 65 (GAD65) using DQ8 tetramers. We demonstrated that GAD65 121-140 and GAD65 250-266 elicited responses from DQ8+ subjects. Circulating CD4+ T cells specific for these epitopes were detected significantly more often in T1D patients than in healthy individuals after in vitro expansion. T cell clones specific for GAD65 121-140 and GAD65 250-266 carried a Th1-dominant phenotype, with some of the GAD65 121-140-specific T cell clones producing IL-17. GAD65 250-266-specific CD4+ T cells could also be detected by direct ex vivo staining. Analysis of unmanipulated peripheral blood mononuclear cells (PBMCs) revealed that GAD65 250-266-specific T cells could be found in both healthy and diabetic individuals but the frequencies of specific T cells were higher in subjects with type 1 diabetes. Taken together, our results suggest a proinflammatory role for T cells specific for DQ8-restricted GAD65 121-140 and GAD65 250-266 epitopes and implicate their possible contribution to the progression of T1D.

Delivering on George Eisenbarth's visionary pursuit of understanding pathogenesis and prevention of type 1 diabetes

George Eisenbarth's pioneering and visionary research has provided a critical foundation that will be built on in the years ahead as we progress toward prevention of type 1 diabetes. His almost 30-year old model that type 1 diabetes was a chronic and predictable autoimmune disease with multiple identifiable progressive stages with a potential for interventions to prevent progression to symptomatic diabetes has stood the test of time. To deliver on the Eisenbarth vision and his "unfinished journey," the field needs: (1) to improve detection of risk of type 1 diabetes, (2) to improve staging and prediction of progression, (3) to perform smaller, shorter, practical, and an increased number of prevention clinical trials, and (4) to increase awareness of the potential for risk detection, staging, and prevention of type 1 diabetes and benefit/risk of prevention.

Celiac disease in type 1 diabetes mellitus

Celiac Disease (CD) occurs in patients with Type 1 Diabetes (T1D) ranging the prevalence of 4.4-11.1% versus 0.5% of the general population. The mechanism of association of these two diseases involves a shared genetic background: HLA genotype DR3-DQ2 and DR4-DQ8 are strongly associated with T1D, DR3-DQ2 with CD. The classical severe presentation of CD rarely occurs in T1D patients, but more often patients have few/mild symptoms of CD or are completely asymptomatic (silent CD). In fact diagnosis of CD is regularly performed by means of the screening in T1D patients. The effects of gluten-free diet (GFD) on the growth and T1D metabolic control in CD/T1D patient are controversial. Regarding of the GFD composition, there is a debate on the higher glycaemic index of gluten-free foods respect to gluten-containing foods; furthermore GFD could be poorer of fibers and richer of fat. The adherence to GFD by children with CD-T1D has been reported generally below 50%, lower respect to the 73% of CD patients, a lower compliance being more frequent among asymptomatic patients. The more severe problems of GFD adherence usually occur during adolescence when in GFD non compliant subjects the lowest quality of life is reported. A psychological and educational support should be provided for these patients.

A girl with type 1 diabetes and a yellowish appearance

Type 1 diabetes mellitus in children has been associated with other autoimmune diseases, especially coeliac disease and autoimmune thyroiditis. This association may be the result of a common pathogenic background. We describe the case of a girl with type 1 diabetes mellitus who developed icterus due to autoimmune hepatitis, a disease rarely found in children. Thyroiditis-associated and diabetes-associated autoantibodies were also present. Human leucocyte antigen typing revealed DRB1*03 heterozygosity, which has been associated with the occurrence of both autoimmune hepatitis and type 1 diabetes. This finding implies that similar pathogenic pathways may be involved in different autoimmune diseases including type 1 diabetes and autoimmune hepatitis. The patient was successfully treated with prednisolone and azathioprine. Autoimmune hepatitis can be a serious co-occurring disease in patients with type 1 diabetes.

The prevalence and risk factors for coeliac disease among children and adolescents with type 1 diabetes mellitus

AIMS

Our aim was to determine in children with T1DM the prevalence of positive antibodies against tissue transglutaminase (anti-tTG IgA) as indices of coeliac disease (CD), as well as its clinical presentation, its determinants and its association with thyroid (anti-TG, anti-TPO) and pancreatic b-cell autoimmunity (anti-GAD).

METHODS

The study included 105 children and adolescents with T1DM, aged (mean±SD) 12.44±4.76 years, with a T1DM duration of 4.41±3.70 years.

RESULTS

Fifty of our patients (47.6%) were positive for anti-GAD, 9/105 (8.6%) for anti-tTG IgA and 21/105(20%) for anti-thyroid antibodies. The anti-tTG IgA (+) children, in comparison with the rest of the study population, were of younger age (9.31 vs. 12.74 years, p=0.038), shorter diabetes duration (2.16 vs. 4.62 years, p=0.056) and had mild growth impairment (height SDS: -0.55 vs. +0.20, p=0.055). Univariate logistic regression analysis revealed that the presence of anti-tTG IgA (+) was associated with younger age and shorter T1DM duration. Only 5/9 (55.6%) children with high titres of anti-tTG IgA developed mild gastrointestinal symptoms or growth retardation and had histological findings typical of CD.

CONCLUSIONS

The prevalence of anti-tTG IgA positivity among T1DM children was 8.6% and its occurrence was associated with younger age and short diabetes duration. Since CD presents in T1DM patients asymptomatically or with non-specific symptoms, periodic autoantibody screening is necessary for its early diagnosis.

Celiac disease associated antibodies in persons with latent autoimmune diabetes of adult and type 2 diabetes

BACKGROUND

Celiac Disease (CD) is present in 1-16.4% of patients with type 1 diabetes mellitus. The most important serological markers of CD are anti-endomysial (EMA), anti-tissue transglutaminase (tTGA) and antigliadin antibodies (AGA).

AIM/HYPOTHESIS

The objective of this work is to determine the frequency of tTGA and/or AGA in latent autoimmune diabetes of adult (LADA) and subjects with type 2 diabetes (T2DM), as well as to evaluate their relation with several clinical and biochemical characteristics.

SUBJECTS AND METHODS

Forty three subjects with LADA and 99 with T2DM were studied. The presence of AGA, tTGA was determined in the sera of these patients. The variables: sex, age, duration of diabetes, treatment, body mass index (BMI) and fasting blood glucose concentration were also recorded.

RESULTS

No differences were found in the frequency of celiac disease associated antibodies between LADA and T2DM subjects. The presence of celiac disease related antibodies was more frequent in patients with a normal or low BMI.

CONCLUSIONS

Celiac disease does not seem to be related with pancreatic autoimmunity in type 2 diabetes. Celiac disease causes a decrease of body mass index in type 2 diabetes while pancreatic islet autoimmunity in this entity masks this effect.

Endocrine autoimmunity in families with type 1 diabetes: frequent appearance of thyroid autoimmunity during late childhood and adolescence

AIMS/HYPOTHESIS

Thyroid autoimmunity clusters with other endocrine and non-endocrine forms of autoimmunity. The aim of this study was to determine the chronological appearance of thyroid autoantibodies in relation to other forms of autoimmunity in at-risk children.

METHODS

The BABYDIAB study follows children of parents with type 1 diabetes. Children born in Germany between 1989 and 2000 were recruited at birth and followed up at 9 months and at 2, 5, 8, 11, 14 and 17 years. Antibodies to thyroid peroxidase were measured in samples taken at the last study visit in 1,489 children and in all previous samples in children who tested positive. Islet antibodies and antibodies to 21-hydroxylase and transglutaminase were also measured in all children. Median follow-up was 8 years.

RESULTS

The cumulative risk for developing antibodies to thyroid peroxidase was 20.3% (95% CI 12.3-28.3) by age 14 years. The risk was increased in girls (adjusted HR 2.0; 95% CI 1.2-3.4; p = 0.008), in children who had multiple first-degree family history of type 1 diabetes (adjusted HR 3.3; 95% CI 1.4-8.0; p = 0.006) and in children who also had antibodies to GAD (adjusted HR 3.0; 95% CI 1.5-5.9; p = 0.001). Thyroid peroxidase antibody appearance was most common from age 8 years and was often the last autoantibody to develop in children with other autoantibodies.

CONCLUSIONS/INTERPRETATION

Among children of patients with type 1 diabetes, the appearance of thyroid autoantibodies is frequent, is not synchronous to the appearance of other autoantibodies and is most common in late childhood and adolescence.

A 20-year-old woman with Hashimoto's thyroiditis and Evans' syndrome

Here we report the case of a 20-year-old female patient previously diagnosed with Hashimoto's thyroiditis and overt hypothyroidism, and who had been taking synthetic thyroxine (100 microg/day) for eight months. She experienced intermittent dizziness and generalized weakness, and was diagnosed as having severe autoimmune hemolytic anemia (AIHA). We prescribed prednisolone treatment and continued synthetic thyroxine administration. Two years and five months later, she developed idiopathic thrombocytopenic purpura (ITP) and was diagnosed with Evans' syndrome. Thereafter, laparoscopic splenectomy was performed because her autoimmune hemolytic anemia was refractory and dependent on steroid therapy. The HLA genotypes of the patient were HLA-A*020101/A* 2602, HLA-B*270502/B*5401, HLA-Cw*0102/Cw*020202, HLA-DRB1*0404/DRB1*0405, and HLA-DQB1*0302/DQ B1*0401. Hashimoto's thyroiditis is often associated with other nonendocrine autoimmune diseases, and antithyroid antibodies are frequently observed in Evans' syndrome (coexistence of AIHA and ITP). However, there is no report of Evans' syndrome developing in patients with overt hypothyroidism and Hashimoto's thyroiditis. This case suggests that three autoimmune diseases (AIHA, ITP, and Hashimoto's thyroiditis) might share a common immunogenetic pathway in pathogenesis.

ADA Outstanding Scientific Achievement Lecture 2004. Thirty years of investigating the autoimmune basis for type 1 diabetes: why can't we prevent or reverse this disease?

Thirty years ago, a convergence of investigational observations lead to the now widely accepted notion that type 1 diabetes results from an autoimmune destruction of insulin-producing beta-cells in subjects genetically predisposed to the disease. Improvements in understanding of the natural history of type 1 diabetes, the biochemical identification of autoantigens, the discovery of spontaneous animal models for the disease, the availability of immune-modulating agents, and other important facets, including disease prediction, drove an early sense of optimism that the prevention of type 1 diabetes was possible and, in some research circles, that ability was thought to be within a not-to-distant reach. Unfortunately, those early expectations proved overly optimistic, and despite the aforementioned knowledge gains, the generation of improved investigational tools, the identification of methods to prevent the disease in animal models, and the formation of very large disease prevention trials, a means to prevent type 1 diabetes in humans continues to remain elusive. Believing in the concept of "informative failures" (a.k.a., wise people learn from their mistakes), this lecture reviews the knowledge base collected over this time period and, when combined with an analysis of those research experiences, sets forth a proposal for future investigations that will, hopefully, turn discoveries into a means for the prevention or reversal of type 1 diabetes.