Genetic Risk For Type 1 Diabetes Research Articles

SH2B3 (lnk) Regulates Type 1 Diabetes Immune Phenotypes

Background: The type 1 diabetes (T1D)-associated risk gene SH2B Adaptor Protein 3 (SH2B3) encodes a phosphatase with specificity for Janus Kinase 2 (JAK2). We hypothesized that variations in SH2B3 would affect immune signaling pathways relevant to T1D autoimmunity. Here we report: 1) Occurrence of the SH2B3 risk variant among T1D patients, unaffected first-degree relatives and controls; 2) Prevalence of SH2B3 risk genotype in African Americans in the Southeastern U.S.; and 3) Alterations to immune composition associated with the SH2B3 risk variant. Approach and Results: 1) The University of Florida Diabetes Institute (UFDI) cohort (n=1946) was analyzed for genetic risk of T1D using a Taqman single nucleotide polymorphism (SNP) genotyping array with coverage of 32 SNPs. Two SNPs (rs3184504 and rs653178) corresponding to SH2B3 were in perfect linkage disequilibrium and will be described here as minor (T1D risk) or common variant. Among Caucasian subjects, the odds ratio (OR) for the minor variant among T1D subjects was 1.30 (1.06-1.59, p=1.42x10-2), similar to previous reports. Among African American subjects, the minor variant OR was elevated (2.93, 1.22-7.03, p=1.30x10-2), representing the most highly-associated non-HLA gene. Complete blood count (CBC, n=954) and flow cytometric human immunophenotyping (HIP, n=252) were performed on a subset of subjects. Individuals carrying the risk variant of SH2B3 had significantly more blood monocytes and neutrophils but similar numbers of lymphocytes compared to non-carriers. HIP revealed a significantly higher frequency of type 1 (CXCR3+) CD8+ T cells in subjects with the risk variant of SH2B3. Conclusions: The risk variant of SH2B3 is associated with both increased risk for T1D and seroconversion in Caucasian and African American subjects. Phenotypically, this element of T1D genetic risk presents as increased frequency of some myeloid cell populations and either expansion or polarization of CD8+ T cells bearing the canonical Th1 chemokine receptor CXCR3. Disclosure A. Camargo: None. D.J. Perry: None. T.M. Brusko: Stock/Shareholder; Self; OneVax, LLC. Advisory Panel; Self; Caladrius Biosciences, Inc.. Consultant; Self; Merck & Co., Inc., Sanofi-Aventis. M.A. Wallet: None.

Type 1 diabetes susceptibility alleles are associated with distinct alterations in the gut microbiota

BackgroundDysbiosis of the gut microbiota has been implicated in the pathogenesis of many autoimmune conditions including type 1 diabetes (T1D). It is unknown whether changes in the gut microbiota observed in T1D are due to environmental drivers, genetic risk factors, or both. Here, we have performed an analysis of associations between the gut microbiota and T1D genetic risk using the non-obese diabetic (NOD) mouse model of T1D and the TwinsUK cohort.ResultsThrough the analysis of five separate colonies of T1D susceptible NOD mice, we identified similarities in NOD microbiome that were independent of animal facility. Introduction of disease protective alleles at the Idd3 and Idd5 loci (IL2, Ctla4, Slc11a1, and Acadl) resulted in significant alterations in the NOD microbiome. Disease-protected strains exhibited a restoration of immune regulatory pathways within the gut which could also be reestablished using IL-2 therapy. Increased T1D disease risk from IL-2 pathway loci in the TwinsUK cohort of human subjects resulted in some similar microbiota changes to those observed in the NOD mouse.ConclusionsThese findings demonstrate for the first time that type 1 diabetes-associated genetic variants that restore immune tolerance to islet antigens also result in functional changes in the gut immune system and resultant changes in the microbiota.

Genetic Risk Scores for Type 1 Diabetes Prediction and Diagnosis.

About 50% of the heritability of type 1 diabetes (T1D) is attributed to human leukocyte antigen (HLA) alleles and the remainder to several (close to 50) non-HLA loci. A current challenge in the field of the genetics of T1D is to apply the knowledge accumulated in the last 40years towards differential diagnosis and risk assessment. T1D genetic risk scores seek to combine the information from HLA and non-HLA alleles to improve the accuracy of diagnosis, prediction, and prognosis. Here, we describe genetic risk scores that have been developed and validated in various settings and populations. Several genetic scores have been proposed that merge disease risk information from multiple genetic factors to optimize the use of genetic information and ultimately improve prediction and diagnosis of T1D.

Diverse type 2 diabetes genetic risk factors functionally converge in a phenotype-focused gene network.

Type 2 Diabetes (T2D) constitutes a global health burden. Efforts to uncover predisposing genetic variation have been considerable, yet detailed knowledge of the underlying pathogenesis remains poor. Here, we constructed a T2D phenotypic-linkage network (T2D-PLN), by integrating diverse gene functional information that highlight genes, which when disrupted in mice, elicit similar T2D-relevant phenotypes. Sensitising the network to T2D-relevant phenotypes enabled significant functional convergence to be detected between genes implicated in monogenic or syndromic diabetes and genes lying within genomic regions associated with T2D common risk. We extended these analyses to a recent multiethnic T2D case-control exome of 12,940 individuals that found no evidence of T2D risk association for rare frequency variants outside of previously known T2D risk loci. Examining associations involving protein-truncating variants (PTV), most at low population frequencies, the T2D-PLN was able to identify a convergent set of biological pathways that were perturbed within four of five independent T2D case/control ethnic sets of 2000 to 5000 exomes each. These same pathways were found to be over-represented among both known monogenic or syndromic diabetes genes and genes within T2D-associated common risk loci. Our study demonstrates convergent biology amongst variants representing different classes of T2D genetic risk. Although convergence was observed at the pathway level, few of the contributing genes were found in common between different cohorts or variant classes, most notably between the exome variant sets which suggests that future rare variant studies may be better focusing their power onto a single population of recent common ancestry.

Differential transcriptome of tolerogenic versus inflammatory dendritic cells points to modulated T1D genetic risk and enriched immune regulation.

Tolerogenic dendritic cells (tolDCs) are assessed as immunomodulatory adjuvants to regulate autoimmunity. The underlying gene expression endorsing their regulatory features remains ill-defined. Using deep mRNA sequencing, we compared transcriptomes of 1,25-dihydroxyvitaminD3/dexametasone-modulated tolDCs with that of non-modulated mature inflammatory DCs (mDCs). Differentially expressed genes controlled cellular interactions, metabolic pathways and endorse tolDCs with the capacity to regulate cell activation through nutrient and signal deprivation, collectively gearing tolDCs into tolerogenic immune regulators. Gene expression differences correlated with protein expression, designating low CD86 and high CD52 on the cell surface as superior discriminators between tolDCs and mDCs. Of 37 candidate genes conferring risk to developing type 1 diabetes (T1D), 11 genes differentially expressed in tolDCs and mDCs regulated immune response and antigen-presenting activity. Differential-expressed transcripts of candidate risk loci for T1D suggest a role of these 'risk genes' in immune regulation, which targeting may modulate the genetic contribution to autoimmunity.

TYPE 2 DIABETES GENETIC RISK VARIANTS WITHIN TCF7L2 ARE ASSOCIATED WITH SMALLER AMYGDALAR VOLUME AMONG DIABETIC ELDERLY PATIENTS

Type 2 diabetes (T2D) is associated with poorer cognitive function, accelerated cognitive decline, and higher risk for dementia, accompanied by atrophy in different brain structures. The association of the Transcription factor 7-like 2 (TCF7L2) gene with T2D is one of the most reproducible findings in T2D genetics. Since TCF7L2 is expressed in the brain, we investigated the association between volumes of the hippocampus, amygdala and frontal cortex of cognitively normal T2D elderly. Our hypothesis was that T2D genetic risk variants within TCF7L2will be associated with greater brain atrophy among diabetic patients. T2D subjects (n=177) from the Israel Diabetes and Cognitive Decline study who were both genotyped for the TCF7L2single nucleotide polymorphisms (SNPs) rs7903146, rs11196205, rs12255372 and underwent brain MRI, were included in this analysis. Images were processed and regional volumes were calculated with SPM software. For each SNP, we used ANCOVA to investigate the association of the T2D risk allele with volume of hippocampus, amygdala and frontal cortex under a recessive model of inheritance - controlling for relevant demographic and clinical variables (sex, age, years of education, duration of T2D, HBA1C, total cholesterol, systolic and diastolic blood pressure, BMI, and ICV [intra-cranial volume]). In all three TCF7L2 SNPs, amygdalar volume was 9–12% lower among carriers of the TD2 risk allele homozygous genotype: rs7903146: TT genotype vs. CT+TT genotypes (p=0.003); rs11196205 CC genotype vs. CG+GG genotypes (p=0.001), and rs12255372TT genotype vs. GT+GG genotypes (p=0.003). These SNPs were not associated with hippocampal or frontal cortex volumes. TCF7L2 genetic variants are associated with smaller amygdalar volume in T2D elderly, suggesting an atrophic process in the amygdala in those with the risk variants. In addition, the amygdala has been implicated in supporting memory processes affected in dementia. Further study of TCF7L2 role in this region is needed, as amygdalar atrophy has been reported in T2D and the amygdala has been recently reported as a glucose sensing region.

Relative contribution of type 1 and type 2 diabetes loci to the genetic etiology of adult-onset, non-insulin-requiring autoimmune diabetes

BackgroundIn adulthood, autoimmune diabetes can present as non-insulin-requiring diabetes, termed as ‘latent autoimmune diabetes in adults’ (LADA). In this study, we investigated established type 1 diabetes (T1D) and type 2 diabetes (T2D) genetic loci in a large cohort of LADA cases to assess where LADA is situated relative to these two well-characterized, classic forms of diabetes.MethodsWe tested the association of T1D and T2D GWAS-implicated loci in 978 LADA cases and 1057 non-diabetic controls of European ancestry using a linear mixed model. We then compared the associations of T1D and T2D loci between LADA and T1D and T2D cases, respectively. We quantified the difference in genetic risk between each given disease at each locus, and also calculated genetic risk scores to quantify how genetic liability to T1D and T2D distinguished LADA cases from controls.ResultsOverall, our results showed that LADA is genetically more similar to T1D, with the exception of an association at the T2D HNF1A locus. Several T1D loci were associated with LADA, including the major histocompatibility complex region, as well as at PTPN22, SH2B3, and INS. Contrary to previous studies, the key T2D risk allele at TCF7L2 (rs7903146-T) had a significantly lower frequency in LADA cases, suggesting that this locus does not play a role in LADA etiology. When constrained on antibody status, the similarity between LADA and T1D became more apparent; however, the HNF1A and TCF7L2 observations persisted.ConclusionLADA is genetically closer to T1D than T2D, although the genetic load of T1D risk alleles is less than childhood-onset T1D, particularly at the major histocompatibility complex region, potentially accounting for the later disease onset. Our results show that the genetic spectrum of T1D extends into adult-onset diabetes, where it can clinically masquerade as T2D. Furthermore, T2D genetic risk plays a small role in LADA, with a degree of evidence for the HNF1A locus, highlighting the potential for genetic risk scores to contribute towards defining diabetes subtypes.

Identification and Validation Novel Risk Genes for Type 1 Diabetes – A Meta-Analysis

Background: Type 1 diabetes (T1D) cannot be explained by environmental factors alone and gene mutations in T1D should be also taken seriously. The aim of this study was to investigate the novel genetic risk of T1D by systematically reviewing the published literature and performing a meta-analysis.Methods: A comprehensive search of electronic databases was completed using Illumina BioEngine. Seven T1D case/control bio-sets from four different studies were selected, including 286 T1D cases and 162 controls. The selected top T1D risk genes were further analyzed integrating an online open source T1D genetic database. Pathway enrichment analysis (PEA) and network connectivity analysis (NCA) were conducted to identify potential functional association between target genes and T1D.Results: Six genes were identified through the meta-analysis as top target genes for T1D: HLA-DQB1, OAS1, CMKLR1, NFE2, MNDA and GPR56. These genes play roles within multiple T1D genetic pathways and demonstrate solid connections with known T1D target genes. NCA results also revealed strong functional association between these genes and T1D.Conclusion: This study identified known as well as novel T1D target genes and their functional pathways that influence the T1D pathogenesis. Our results may provide new insights for the understanding of the genetic mechanisms of T1D.

Type 1 Diabetes Genetic Risk Score: A Novel Tool to Discriminate Monogenic and Type 1 Diabetes.

Distinguishing patients with monogenic diabetes from those with type 1 diabetes (T1D) is important for correct diagnosis, treatment, and selection of patients for gene discovery studies. We assessed whether a T1D genetic risk score (T1D-GRS) generated from T1D-associated common genetic variants provides a novel way to discriminate monogenic diabetes from T1D. The T1D-GRS was highly discriminative of proven maturity-onset diabetes of young (MODY) (n = 805) and T1D (n = 1,963) (receiver operating characteristic area under the curve 0.87). A T1D-GRS of >0.280 (>50th T1D centile) was indicative of T1D (94% specificity, 50% sensitivity). We then analyzed the T1D-GRS of 242 white European patients with neonatal diabetes (NDM) who had been tested for all known NDM genes. Monogenic NDM was confirmed in 90, 59, and 8% of patients with GRS <5th T1D centile, 50-75th T1D centile, and >75th T1D centile, respectively. Applying a GRS 50th T1D centile cutoff in 48 NDM patients with no known genetic cause identified those most likely to have a novel monogenic etiology by highlighting patients with probable early-onset T1D (GRS >50th T1D centile) who were diagnosed later and had less syndromic presentation but additional autoimmune features compared with those with proven monogenic NDM. The T1D-GRS is a novel tool to improve the use of biomarkers in the discrimination of monogenic diabetes from T1D.

Gene-Diet Interactions in Type 2 Diabetes

Type 2 diabetes (T2D) is thought to arise from an interaction between susceptibility genes and a diabetogenic environment. This review summarizes progress pertaining specifically to gene-diet interactions. Recent efforts have been population-based and have focused on established genetic and dietary risk factors for T2D. TCF7L2 × carbohydrate-quality and IRS1 × macronutrient-composition interactions are promising factors, but most studies of gene-diet interactions are conflicting or need follow-up. T2D genetic risk scores are powerful predictors of developing T2D, but whether they can be combined with dietary risk factors merits further study. Lack of statistical power, imprecise diet measures, and conceptual issues surrounding replication all challenge our efforts to characterize interactions. Collaborations are needed for optimal study designs in both hypothesis-testing and hypothesis-generating contexts. Continued investment in studies of gene-diet interactions may lead to novel mechanistic insights into T2D, opportunities for risk stratification, and ultimately to personalized nutrition to prevent the disease.

Gene-lifestyle interaction and type 2 diabetes: the EPIC interact case-cohort study.

Understanding of the genetic basis of type 2 diabetes (T2D) has progressed rapidly, but the interactions between common genetic variants and lifestyle risk factors have not been systematically investigated in studies with adequate statistical power. Therefore, we aimed to quantify the combined effects of genetic and lifestyle factors on risk of T2D in order to inform strategies for prevention. The InterAct study includes 12,403 incident T2D cases and a representative sub-cohort of 16,154 individuals from a cohort of 340,234 European participants with 3.99 million person-years of follow-up. We studied the combined effects of an additive genetic T2D risk score and modifiable and non-modifiable risk factors using Prentice-weighted Cox regression and random effects meta-analysis methods. The effect of the genetic score was significantly greater in younger individuals (p for interaction = 1.20×10-4). Relative genetic risk (per standard deviation [4.4 risk alleles]) was also larger in participants who were leaner, both in terms of body mass index (p for interaction = 1.50×10-3) and waist circumference (p for interaction = 7.49×10-9). Examination of absolute risks by strata showed the importance of obesity for T2D risk. The 10-y cumulative incidence of T2D rose from 0.25% to 0.89% across extreme quartiles of the genetic score in normal weight individuals, compared to 4.22% to 7.99% in obese individuals. We detected no significant interactions between the genetic score and sex, diabetes family history, physical activity, or dietary habits assessed by a Mediterranean diet score. The relative effect of a T2D genetic risk score is greater in younger and leaner participants. However, this sub-group is at low absolute risk and would not be a logical target for preventive interventions. The high absolute risk associated with obesity at any level of genetic risk highlights the importance of universal rather than targeted approaches to lifestyle intervention.

Maternal and offspring fasting glucose and type 2 diabetes-associated genetic variants and cognitive function at age 8: a Mendelian randomization study in the Avon Longitudinal Study of Parents and Children

BackgroundIn observational epidemiological studies type 2 diabetes (T2D) and both low and high plasma concentrations of fasting glucose have been found to be associated with lower cognitive performance. These associations could be explained by confounding.MethodsIn this study we looked at the association between genetic variants, known to be robustly associated with fasting glucose and T2D risk, in the mother and her offspring to determine whether there is likely to be a causal link between early life exposure to glucose and child’s intelligence quotient (IQ) scores in the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. We generated a fasting glucose (FGGRS) and a T2D (T2DGRS) genetic risk score and used them in a Mendelian randomization approach.ResultsWe found a strong correlation between the FGGRS and fasting glucose plasma measurements that were available for a subset of children, but no association of either the maternal or the offspring FGGRS with child’s IQ was observed. In contrast, the maternal T2DGRS was positively associated with offspring IQ.ConclusionsMaternal and offspring genetic variants which are associated with glucose levels are not associated with offspring IQ, suggesting that there is unlikely to be a causal link between glucose exposure in utero and IQ in childhood. Further exploration in even larger cohorts is required to exclude the possibility that our null findings were due to a lack of statistical power.

Allele Summation of Diabetes Risk Genes Predicts Impaired Glucose Tolerance in Female and Obese Individuals

IntroductionSingle nucleotide polymorphisms (SNPs) in approximately 40 genes have been associated with an increased risk for type 2 diabetes (T2D) in genome-wide association studies. It is not known whether a similar genetic impact on the risk of prediabetes (impaired glucose tolerance [IGT] or impaired fasting glycemia [IFG]) exists.MethodsIn our cohort of 1442 non-diabetic subjects of European origin (normal glucose tolerance [NGT] n = 1046, isolated IFG n = 142, isolated IGT n = 140, IFG+IGT n = 114), an impact on glucose homeostasis has been shown for 9 SNPs in previous studies in this specific cohort. We analyzed these SNPs (within or in the vicinity of the genes TCF7L2, KCNJ11, HHEX, SLC30A8, WFS1, KCNQ1, MTNR1B, FTO, PPARG) for association with prediabetes.ResultsThe genetic risk load was significantly associated with the risk for IGT (p = 0.0006) in a model including gender, age, BMI and insulin sensitivity. To further evaluate potential confounding effects, we stratified the population on gender, BMI and insulin sensitivity. The association of the risk score with IGT was present in female participants (p = 0.008), but not in male participants. The risk score was significantly associated with IGT (p = 0.008) in subjects with a body mass index higher than 30 kg/m2 but not in non-obese individuals. Furthermore, only in insulin resistant subjects a significant association between the genetic load and the risk for IGT (p = 0.01) was found.DiscussionWe found that T2D genetic risk alleles cause an increased risk for IGT. This effect was not present in male, lean and insulin sensitive subjects, suggesting a protective role of beneficial environmental factors on the genetic risk.

Type 2 diabetes risk alleles demonstrate extreme directional differentiation among human populations, compared to other diseases.

Many disease-susceptible SNPs exhibit significant disparity in ancestral and derived allele frequencies across worldwide populations. While previous studies have examined population differentiation of alleles at specific SNPs, global ethnic patterns of ensembles of disease risk alleles across human diseases are unexamined. To examine these patterns, we manually curated ethnic disease association data from 5,065 papers on human genetic studies representing 1,495 diseases, recording the precise risk alleles and their measured population frequencies and estimated effect sizes. We systematically compared the population frequencies of cross-ethnic risk alleles for each disease across 1,397 individuals from 11 HapMap populations, 1,064 individuals from 53 HGDP populations, and 49 individuals with whole-genome sequences from 10 populations. Type 2 diabetes (T2D) demonstrated extreme directional differentiation of risk allele frequencies across human populations, compared with null distributions of European-frequency matched control genomic alleles and risk alleles for other diseases. Most T2D risk alleles share a consistent pattern of decreasing frequencies along human migration into East Asia. Furthermore, we show that these patterns contribute to disparities in predicted genetic risk across 1,397 HapMap individuals, T2D genetic risk being consistently higher for individuals in the African populations and lower in the Asian populations, irrespective of the ethnicity considered in the initial discovery of risk alleles. We observed a similar pattern in the distribution of T2D Genetic Risk Scores, which are associated with an increased risk of developing diabetes in the Diabetes Prevention Program cohort, for the same individuals. This disparity may be attributable to the promotion of energy storage and usage appropriate to environments and inconsistent energy intake. Our results indicate that the differential frequencies of T2D risk alleles may contribute to the observed disparity in T2D incidence rates across ethnic populations.

Genetic Susceptibility to Type 2 Diabetes and Breast Cancer Risk in Women of European and African Ancestry

Epidemiologic studies have reported a positive association between type 2 diabetes (T2D) and breast cancer risk, independent of body weight. We investigated 40 genetic variants known to be associated with T2D in relation to breast cancer risk among 2,651 breast cancer cases and 2,520 controls of African or European ancestry that were pooled from seven studies. We found that two T2D risk alleles in Caucasian women (rs5945326-G, rs12518099-C) and one in women of African ancestry (rs7578597-T) were positively associated with breast cancer risk at a nominal significance level of 0.05, whereas two T2D risk alleles were inversely associated with breast cancer risk in Caucasian women (rs1111875-C, rs10923931-T). The composite T2D susceptibility score (the number of risk allele) was not significantly associated with breast cancer risk. The association between established T2D genetic susceptibility variants and breast cancer risk in women of African or European ancestry is likely weak, if it does exist. The pleiotropic effects of known T2D risk alleles cannot explain the association between T2D and breast cancer risk.

Genetic Risk Assessment of Type 2 Diabetes–Associated Polymorphisms in African Americans

OBJECTIVEMultiple single nucleotide polymorphisms (SNPs) associated with type 2 diabetes (T2D) susceptibility have been identified in predominantly European-derived populations. These SNPs have not been extensively investigated for individual and cumulative effects on T2D risk in African Americans.RESEARCH DESIGN AND METHODSSeventeen index T2D risk variants were genotyped in 2,652 African American case subjects with T2D and 1,393 nondiabetic control subjects. Individual SNPs and cumulative risk allele loads were assessed for association with risk for T2D. Cumulative risk was assessed by counting risk alleles and evaluating the difference in cumulative risk scores between case subjects and control subjects. A second analysis weighted risk scores (ln [OR]) based on previously reported European-derived effect sizes.RESULTSFrequencies of risk alleles ranged from 8.6 to 99.9%. Eleven SNPs had ORs >1, and 5 from ADAMTS9, WFS1, CDKAL1, JAZF1, and TCF7L2 trended or had nominally significant evidence of T2D association (P < 0.05). Individuals carried between 13 and 29 risk alleles. Association was observed between T2D and increase in risk allele load (unweighted OR 1.04 [95% CI 1.01–1.08], P = 0.010; weighted 1.06 [1.03–1.10], P = 8.10 × 10−5). When TCF7L2 SNP rs7903146 was included as a covariate, the risk score was no longer associated with T2D in either model (unweighted 1.02 [0.98–1.05], P = 0.33; weighted 1.02 [0.98–1.06], P = 0.40).CONCLUSIONSThe trend of increase in risk for T2D with increasing risk allele load is similar to observations in European-derived populations; however, these analyses indicate that T2D genetic risk is primarily mediated through the effect of TCF7L2 in African Americans.

Exploring the diabetogenicity of the HLA-B18-DR3 CEH: independent association with T1D genetic risk close to HLA-DOA

The objective of this study was to identify additional diabetes susceptibility markers in the MHC that could be responsible for the differential diabetogenicity of different HLA-DR3 CEHs. High-resolution SNP genotyping of the MHC was carried out in 15 type 1 diabetes (T1D) patients and 39 non-diabetic controls, homozygous for DR3-DQ2 and with one copy of the A(*)30-B(*)18-MICA(*)4-F1C30-DRB1(*)0301-DQB1(*)0201-DPB1(*)0202 HLA haplotype. Significantly associated SNPs were replicated in an independent sample of 554 T1D patients and 841 controls without HLA matching. Electrophoretic mobility shift assay was used to show a functional effect of an associated SNP. Seven SNPs showed evidence of association in the initial discovery experiment. Upon replication, only rs419434 (upstream HLA-DOA gene) remained significant. A functional variant (rs432375) in complete LD with rs419434 was shown to affect USF-1 binding and could be responsible for the association signal in the region. We have identified a new susceptibility locus within the MHC with a modest contribution to T1D (OR=1.93; CI: 1.52-2.44; P=10(-8)) that is independent of HLA-DRB1 locus.

Poor In Vitro Maturation and Pro‐Inflammatory Cytokine Response of Dendritic Cells in Children at Genetic Risk of Type 1 Diabetes

Type 1 diabetes (T1D) has been associated with an aberrant maturation of dendritic cells (DC). We studied the maturation of monocyte-derived DC in children with newly diagnosed T1D and in healthy children with genetic risk for T1D. Peripheral blood monocytes from children with newly diagnosed T1D (n = 12; mean age 13.2 years), children with human leukocyte antigen (HLA)-risk genotype of T1D (n = 7; mean age 12.7 years) and healthy children (n = 14; mean age 11.2 years) were in vitro differentiated into DC. Expression of HLA-DR, CD80/86 and CD11c and secretion of interleukin (IL)-12, tumor necrosis factor (TNF)-alpha, IL-6 and IL-10 were measured using flow cytometry. Lower percentage of DC expressed CD11c and HLA-DR, and decreased production of TNF-alpha was found in children with newly diagnosed T1D and in children at genetic risk when compared to healthy children. Children with risk genotype also had decreased IL-12 production by DC. Children with T1D and children at genetic risk of T1D appear to have similar aberrancies in the maturation of DC, which may predispose to beta-cell autoimmunity.