Increasing incidence of Type 1 diabetes--role for genes?

Sex-dependent effects of bisphenol A on type 1 diabetes development in non-obese diabetic (NOD) mice

Type 1 diabetes (T1D) is an autoimmune disease caused by immune-mediated pancreatic β-cell destruction. The endocrine disrupting chemical bisphenol A (BPA) has widespread human exposure and can modulate immune function and the gut microbiome (GMB), which may contribute to the increasing T1D incidence worldwide. It was hypothesized that BPA had sex-dependent effects on T1D by modulating immune homeostasis and GMB. Adult female and male non-obese diabetic (NOD) mice were orally administered BPA at environmentally relevant doses (30 or 300 µg/kg). Antibiotic-treated adult NOD females were exposed to 0 or 30 µg/kg BPA. BPA accelerated T1D development in females, but delayed males from T1D. Consistently, females had a shift towards pro-inflammation (e.g., increased macrophages and Bacteroidetes), while males had increases in anti-inflammatory immune factors and a decrease in both anti- and pro-inflammatory GMB. Although bacteria altered during sub-acute BPA exposure differed from bacteria altered from chronic BPA exposure in both sexes, the GMB profile was consistently pro-inflammatory in females, while males had a general decrease of both anti- and pro-inflammatory gut microbes. However, treatment of females with the antibiotic vancomycin failed to prevent BPA-induced glucose intolerance, suggesting changes in Gram-positive bacteria were not a primary mechanism. In conclusion, BPA exposure was found to have sex dimorphic effects on T1D with detrimental effects in females, and immunomodulation was identified as the primary mechanism.

A stochastic epigenetic Mendelian oligogenic disease model for type 1 diabetes

The incidence of type 1 diabetes (T1D) and some other complex diseases is increasing. The cause has been attributed to an undefined changing environment. We examine the role of the environment (or any changing non-genetic mechanism) in causing the rising incidence, and find much evidence against it: 1) Dizygotic twin T1D concordance is the same as siblings of patients in general; 2) If the environment is responsible for both the discordance among identical twins of patients with T1D and its rising incidence, the twin concordance rate should be rising, but it is not; 3) Migrants from high-to low-incidence countries continue to have high-incidence children; 4) TID incidence among the offspring of two T1D parents is identical to the monozygotic twin rate. On the other hand, genetic association studies of T1D have revealed strong susceptibility in the major histocompatibility complex and many optional additive genes of small effect throughout the human genome increasing T1D risk. We have, from an analysis of previously published family studies, developed a stochastic epigenetic Mendelian oligogenic (SEMO) model consistent with published observations. The model posits a few required recessive causal genes with incomplete penetrance explaining virtually all of the puzzling features of T1D, including its rising incidence and the specific low T1D incidence rates among first-degree relatives of patients. Since historic selection against any causal gene could prevent T1D, we postulate that the rising incidence is because of increasing population mixing of parents from some previously isolated populations that had selected against different causal genes.

Decreased levels of keratin 8 sensitize mice to streptozotocin-induced diabetes

AIM

Diabetes is a result of an interplay between genetic, environmental and lifestyle factors. Keratin intermediate filaments are stress proteins in epithelial cells, and keratin mutations predispose to several human diseases. However, the involvement of keratins in diabetes is not well known. K8 and its partner K18 are the main β-cell keratins, and knockout of K8 (K8^-/- ) in mice causes mislocalization of glucose transporter 2, mitochondrial defects, reduced insulin content and altered systemic glucose/insulin control. We hypothesize that K8/K18 offer protection during β-cell stress and that decreased K8 levels contribute to diabetes susceptibility.

METHODS

K8-heterozygous knockout (K8^+/- ) and wild-type (K8^+/+ ) mice were used to evaluate the influence of keratin levels on endocrine pancreatic function and diabetes development under basal conditions and after T1D streptozotocin (STZ)-induced β-cell stress and T2D high-fat diet (HFD).

RESULTS

Murine K8^+/- endocrine islets express ~50% less K8/K18 compared with K8^+/+ . The decreased keratin levels have little impact on basal systemic glucose/insulin regulation, β-cell health or insulin levels. Diabetes incidence and blood glucose levels are significantly higher in K8^+/- mice after low-dose/chronic STZ treatment, and STZ causes more β-cell damage and polyuria in K8^+/- compared with K8^+/+ . K8 appears upregulated 5 weeks after STZ treatment in K8^+/+ islets but not in K8^+/- . K8^+/- mice showed no major susceptibility risk to HFD compared to K8^+/+ .

CONCLUSION

Partial K8 deficiency reduces β-cell stress tolerance and aggravates diabetes development in response to STZ, while there is no major susceptibility to HFD.

Deviant development of pancreatic beta cells from embryonic exposure to PCB-126 in zebrafish

Exposures to co-planar PCBs and dioxins have been associated with diabetes in epidemiologic studies. Individuals may be predisposed to diseases such as diabetes as a result of exposure to environmental contaminants during early life, resulting in dysmorphic pancreatic islets or metabolically fragile β-cells. We tested the hypothesis that embryonic exposure to a model Ahr-ligand, PCB-126 would cause structural and/or functional alterations to the developing primary pancreatic islet in the zebrafish (Danio rerio). To assess β-cell development, transgenic zebrafish embryos (Tg(ins:GFP) and Tg(ins:mcherry) were exposed to nominal concentrations of 2 or 5nM PCB-126 or DMSO from 24-48h post fertilization (hpf), and imaged via time-lapse microscopy from 80-102hpf. We identified defects including hypomorphic islets, altered islet migration, islet fragmentation, and formation of ectopic β-cells. As we recently showed the transcription factor Nrf2a is protective in PCB-126 embryotoxicity, we then assessed the transcriptional function of the islets in wildtype and nrf2a(fh318/fh318) mutant embryos. We measured gene expression of preproinsulin a, somatostatin2, pdx1, ghrelin, and glucagon. Expression of preproinsulin a increased with PCB treatment in wildtype embryos, while expression of all measured pancreas genes was altered by the nrf2a mutant genotype, suggesting misregulation of the glucose homeostasis axis in those embryos, independent of PCB treatment. This study shows that embryonic exposure to PCB-126 can result in deviant development of the pancreatic islet and suggests that Nrf2a plays a role in regulating glucose homeostasis during development.

Genistein protects female nonobese diabetic mice from developing type 1 diabetes when fed a soy- and alfalfa-free diet

The objective of this study was to determine the effects of the phytoestrogen genistein (GEN) on the time of onset and/or the incidence of type 1 diabetes (T1D) in female nonobese diabetic (NOD) mice, when administered GEN by gavage once every day for up to 180 days. Five groups of mice (approximately 24 animals/group; 6-7 weeks of age) were included: naive control, vehicle control (25 mM Na2CO3 in water), and 3 GEN treatment groups (2 mg/kg, 6 mg/kg, and 20 mg/kg). Mice were maintained on a soy- and alfalfa-free diet (5K96) during the study and were monitored for blood glucose changes every week. When compared to the vehicle control, exposure to 2-mg/kg GEN produced significant decreases ranging from 55 to 79% in the total incidences of diabetes (blood glucose ≥ 250 mg/dl) and severe diabetes (blood glucose ≥ 400 mg/dl) starting at week 14 of the study. However, during the later stages of the study (i.e., after week 23), the 2-mg/kg dose had no effect on disease incidence. In animals treated with 6-mg/kg and 20-mg/kg GEN, significant decreases in the total incidence of diabetes were observed starting at week 16, while the incidence of severe diabetes was significantly decreased with the changes being observed initially at weeks 18 and 17 for the 6-mg/kg and 20-mg/kg GEN treatment groups, respectively. Several lines of evidence, including histopathological analysis, suggested that GEN protected the pancreas from autoimmune destruction. However, this protective effect of GEN was absent when female NOD mice were maintained on NTP-2000 rodent diet, which contained 5% soybean meal and 7.5% alfalfa meal (the total concentrations of phytoestrogens ranged between 95 and 134 mg/kg). In summary, oral dosing of GEN reduced the incidence and increased the time to onset of T1D in female NOD mice but only when fed a soy- and alfalfa-free diet.

Intensive glucose control versus conventional glucose control for type 1 diabetes mellitus

BACKGROUND

Clinical guidelines differ regarding their recommended blood glucose targets for patients with type 1 diabetes and recent studies on patients with type 2 diabetes suggest that aiming at very low targets can increase the risk of mortality.

OBJECTIVES

To assess the effects of intensive versus conventional glycaemic targets in patients with type 1 diabetes in terms of long-term complications and determine whether very low, near normoglycaemic values are of additional benefit.

SEARCH METHODS

A systematic literature search was performed in the databases The Cochrane Library, MEDLINE and EMBASE. The date of the last search was December 2012 for all databases.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that had defined different glycaemic targets in the treatment arms, studied patients with type 1 diabetes, and had a follow-up duration of at least one year.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data, assessed studies for risk of bias, with differences resolved by consensus. Overall study quality was evaluated by the 'Grading of Recommendations Assessment, Development, and Evaluation' (GRADE) system. Random-effects models were used for the main analyses and the results are presented as risk ratios (RR) with 95% confidence intervals (CI) for dichotomous outcomes.

MAIN RESULTS

We identified 12 trials that fulfilled the inclusion criteria, including a total of 2230 patients. The patient populations varied widely across studies with one study only including children, one study only including patients after a kidney transplant, one study with newly diagnosed adult patients, and several studies where patients had retinopathy or microalbuminuria at baseline. The mean follow-up duration across studies varied between one and 6.5 years. The majority of the studies were carried out in the 1980s and all trials took place in Europe or North America. Due to the nature of the intervention, none of the studies could be carried out in a blinded fashion so that the risk of performance bias, especially for subjective outcomes such as hypoglycaemia, was present in all of the studies. Fifty per cent of the studies were judged to have a high risk of bias in at least one other category.Under intensive glucose control, the risk of developing microvascular complications was reduced compared to conventional treatment for a) retinopathy: 23/371 (6.2%) versus 92/397 (23.2%); RR 0.27 (95% CI 0.18 to 0.42); P < 0.00001; 768 participants; 2 trials; high quality evidence; b) nephropathy: 119/732 (16.3%) versus 211/743 (28.4%); RR 0.56 (95% CI 0.46 to 0.68); P < 0.00001; 1475 participants; 3 trials; moderate quality evidence; c) neuropathy: 29/586 (4.9%) versus 86/617 (13.9%); RR 0.35 (95% CI 0.23 to 0.53); P < 0.00001; 1203 participants; 3 trials; high quality evidence. Regarding the progression of these complications after manifestation, the effect was weaker (retinopathy) or possibly not existent (nephropathy: RR 0.79 (95% CI 0.37 to 1.70); P = 0.55; 179 participants with microalbuminuria; 3 trials; very low quality evidence); no adequate data were available regarding the progression of neuropathy. For retinopathy, intensive glucose control reduced the risk of progression in studies with a follow-up duration of at least two years (85/366 (23.2%) versus 154/398 (38.7%); RR 0.61 (95% CI 0.49 to 0.76); P < 0.0001; 764 participants; 2 trials; moderate quality evidence), while we found evidence for an initial worsening of retinopathy after only one year of intensive glucose control (17/49 (34.7%) versus 7/47 (14.9%); RR 2.32 (95% CI 1.16 to 4.63); P = 0.02; 96 participants; 2 trials; low quality evidence).Major macrovascular outcomes (stroke and myocardial infarction) occurred very rarely, and no firm evidence could be established regarding these outcome measures (low quality evidence).We found that intensive glucose control increased the risk for severe hypoglycaemia, however the results were heterogeneous and only the 'Diabetes Complications Clinical Trial' (DCCT) showed a clear increase in severe hypoglycaemic episodes under intensive treatment. A subgroup analysis according to the baseline haemoglobin A1c (HbA1c) of participants in the trials (low quality evidence) suggests that the risk of hypoglycaemia is possibly only increased for patients who started with relatively low HbA1c values (< 9.0%). Several of the included studies also showed a greater weight gain under intensive glucose control, and the risk of ketoacidosis was only increased in studies using insulin pumps in the intensive treatment group (very low quality evidence).Overall, all-cause mortality was very low in all studies (moderate quality evidence) except in one study investigating renal allograft as treatment for end-stage diabetic nephropathy. Health-related quality of life was only reported in the DCCT trial, showing no statistically significant differences between the intervention and comparator groups (moderate quality evidence). In addition, only the DCCT published data on costs, indicating that intensive glucose therapy control was highly cost-effective considering the reduction of potential diabetes complications (moderate quality evidence).

AUTHORS' CONCLUSIONS

Tight blood sugar control reduces the risk of developing microvascular diabetes complications. The evidence of benefit is mainly from studies in younger patients at early stages of the disease. Benefits need to be weighed against risks including severe hypoglycaemia, and patient training is an important aspect in practice. The effects of tight blood sugar control seem to become weaker once complications have been manifested. However, further research is needed on this issue. Furthermore, there is a lack of evidence from RCTs on the effects of tight blood sugar control in older patient populations or patients with macrovascular disease. There is no firm evidence for specific blood glucose targets and treatment goals need to be individualised taking into account age, disease progression, macrovascular risk, as well as the patient's lifestyle and disease management capabilities.

The trends and the risk of type 1 diabetes over the past 40 years: an analysis by birth cohorts and by parental migration background in Sweden

OBJECTIVE

To investigate the trends and the risk of developing type 1 diabetes in the offspring of Swedes and immigrants by specific parental migration background, age, sex and birth cohort.

DESIGN

Registry-based cohort study.

SETTING

Using Swedish nationwide data we analysed the risk of developing type 1 diabetes in 3 457 486 female and 3 641 304 male offspring between 0 and 30 years of age, born to native Swedes or immigrants and born and living in Sweden between 1969 and 2009. We estimated incidence rate ratios (IRRs) with 95% CIs using Poisson regression models. We further calculated age-standardised rates (ASRs) of type 1 diabetes, using the world population as standard.

RESULTS

We observed a trend of increasing ASRs among offspring below 15 years of age born to native Swedes and a less evident increase among offspring of immigrants. We further observed a shift towards a younger age at diagnosis in younger birth cohorts in both groups of offspring.Compared with offspring of Swedes, children (0-14 years) and young adults (15-30 years) with one parent born abroad had an overall 30% and 15-20% lower IRR, respectively, after multivariable adjustment. The reduction in IRR was even greater among offspring of immigrants if both parents were born abroad. Analysis by specific parental region of birth revealed a 45-60% higher IRR among male and female offspring aged 0-30 years of Eastern Africa.

CONCLUSIONS

Parental country of birth and early exposures to environmental factors play an important role in the aetiology of type 1 diabetes.

Does farm environment protect against type 1 diabetes mellitus?

AIMS/HYPOTHESIS

Hygiene hypothesis has been shown valid in respect of allergies and asthma but has not been, however, sufficiently studied in relation to type 1 diabetes mellitus. This study investigates the effect of childhood farm environment on the prevalence of type 1 diabetes mellitus in Finnish children and young adults.

METHODS

Data come from a questionnaire study carried out in 2007 (N = 5805). Prevalence of type 1 diabetes mellitus was analysed according to the type of the rural exposure below the age of 18 years. Associations were estimated and tested using Bayesian methods.

RESULTS

Consistent suggestive evidence of the inverse association of childhood's farm environment with the occurrence of type 1 diabetes mellitus was shown, even though conclusive results were not reached.

CONCLUSION/INTERPRETATION

Exposure to a broad variety of non-pathogenic environmental microorganisms during childhood might have a protective effect on type 1 diabetes mellitus. Results clearly suggest that further research is well grounded with larger samples.

Temporal trends of HLA, CTLA-4 and PTPN22 genotype frequencies among type 1 diabetes in Continental Italy

The incidence of type 1 diabetes has, progressively, increased worldwide over the last decades and also in Continental Italian population. Previous studies performed in northern European countries, showed, alongside a general increase in the disease incidence, a decreasing frequency of the highest risk HLA genotype in type 1 diabetes populations, thus emphasizing the role of environmental factors. The aim of the study was to evaluate whether a decreasing trend of high risk HLA, CTLA-4 and PTPN22 genotypes would be present in type 1 diabetes subjects of Continental Italy, a country considered at low incidence of the disease compared to northern European populations. N = 765 type 1 diabetes patients diagnosed from 1980 to 2012 in Lazio region were included. For HLA, CTLA4 and PTPN22 temporal trend evaluation, subjects were subdivided into groups of years according to age at diagnosis. All subjects were typed for HLA-DRB1 and DQB1 by a reverse line blot. The CT60 polymorphism of the CTLA4 and C1858T of the PTPN22 gene were genotyped using ABI PRISM 7900HT (n = 419 and n = 364 respectively). HLA genotypes were divided in high, moderate and low risk categories. The proportion of the HLA risk categories was not statistically different over the three decades in subjects with age of onset <15 years and ≥ 15 years. The genotype distribution of CT60 polymorphism of CTLA4 gene did not show any change in the frequencies during time. The analysis of the PTPN22 C1858T variant revealed, instead, that the frequency of CT+TT susceptibility genotypes decreased during time (23.9% vs 13.6%, p = 0.017). We can hypothesize that the pressure of the diabetogenic environment could be milder and therefore not sufficient to reduce the need of a strong genetic background (HLA) "to precipitate" diabetes; the increased pressure of the environment could have, instead, some effects on minor susceptibility genes in our population.

Enterovirus-induced gene expression profile is critical for human pancreatic islet destruction

AIMS/HYPOTHESIS

Virally induced inflammatory responses, beta cell destruction and release of beta cell autoantigens may lead to autoimmune reactions culminating in type 1 diabetes. Therefore, viral capability to induce beta cell death and the nature of virus-induced immune responses are among key determinants of diabetogenic viruses. We hypothesised that enterovirus infection induces a specific gene expression pattern that results in islet destruction and that such a host response pattern is not shared among all enterovirus infections but varies between virus strains.

METHODS

The changes in global gene expression and secreted cytokine profiles induced by lytic or benign enterovirus infections were studied in primary human pancreatic islet using DNA microarrays and viral strains either isolated at the clinical onset of type 1 diabetes or capable of causing a diabetes-like condition in mice.

RESULTS

The expression of pro-inflammatory cytokine genes (IL-1-α, IL-1-β and TNF-α) that also mediate cytokine-induced beta cell dysfunction correlated with the lytic potential of a virus. Temporally increasing gene expression levels of double-stranded RNA recognition receptors, antiviral molecules, cytokines and chemokines were detected for all studied virus strains. Lytic coxsackievirus B5 (CBV-5)-DS infection also downregulated genes involved in glycolysis and insulin secretion.

CONCLUSIONS/INTERPRETATION

The results suggest a distinct, virus-strain-specific, gene expression pattern leading to pancreatic islet destruction and pro-inflammatory effects after enterovirus infection. However, neither viral replication nor cytotoxic cytokine production alone are sufficient to induce necrotic cell death. More likely the combined effect of these and possibly cellular energy depletion lie behind the enterovirus-induced necrosis of islets.

Early seroconversion and rapidly increasing autoantibody concentrations predict prepubertal manifestation of type 1 diabetes in children at genetic risk

AIMS/HYPOTHESIS

The aim of the study was to investigate the timing of the appearance of autoantibodies associated with type 1 diabetes between birth and puberty, the natural fate of these autoantibodies and the predictive power of autoantibody concentrations for early progression to clinical diabetes.

METHODS

Children were recruited to the Type 1 Diabetes Prediction and Prevention Project, an ongoing study based on HLA-conferred genetic risk. Autoantibodies against islet cells, insulin, GAD65 and islet antigen 2 were analysed at 3-12 month intervals, starting from birth.

RESULTS

During the follow-up, 1,320 children (18.4% of the cohort of 7,165 children) were autoantibody positive in at least one sample. Altogether, 184 autoantibody-positive children progressed to type 1 diabetes. Seroconversion occurred at an early age in the progressors (median 1.5 years), among whom 118 (64%) and 150 (82%) seroconverted to autoantibody positivity before the age of 2 and 3 years, respectively. The incidence of seroconversion peaked at 1 year of age. Compared with other autoantibody-positive children, the median autoantibody levels were already markedly higher 3 to 6 months after the seroconversion in children who later progressed to diabetes.

CONCLUSIONS/INTERPRETATION

Early initiation of autoimmunity and rapid increases in autoantibody titres strongly predict progression to overt diabetes before puberty, emphasising the importance of early life events in the development of type 1 diabetes.

Breastfeeding protects against type 1 diabetes mellitus: a case-sibling study

BACKGROUND

Some epidemiological studies have shown a protective effect of breastfeeding against type 1 diabetes mellitus (T1DM), whereas others have found opposite results. The role of early exposure to cow's milk protein and shorter duration of breastfeeding are still controversial. This study aimed to compare the frequency and duration of breastfeeding among siblings with and without T1DM.

METHODS

A case-control study was conducted at the Prof. Fernando Figueira Institute of Integral Medicine, Recife, PE, Brazil, between June 2009 and August 2010. The case patients were children with T1DM, and the controls were their unaffected sibling. The World Health Organization criteria for T1DM were used. All T1DM cases had the diagnostic criteria confirmed by checking their medical records. Data on infant feeding during the first year of life, prenatal care, gestational age, delivery, birth weight, and immunization status were collected through information provided by the mothers.

RESULTS

In total, 123 children with diabetes mellitus type 1 and their respective siblings were studied. There was no difference in breastfeeding rates among the two groups, but patients with diabetes had a shorter duration of breastfeeding (3.3 vs. 4.6 months, p < 0.001). The diabetic group was exposed earlier to cow's milk. After controlling for other associated variables it was shown that a longer duration of breastfeeding was associated with a protective effect against diabetes.

CONCLUSIONS

Our data support the proposal that a shorter breastfeeding interval may contribute to T1DM in Brazilian children.

Noninvasive measurement of plasma glucose from exhaled breath in healthy and type 1 diabetic subjects

Effective management of diabetes mellitus, affecting tens of millions of patients, requires frequent assessment of plasma glucose. Patient compliance for sufficient testing is often reduced by the unpleasantness of current methodologies, which require blood samples and often cause pain and skin callusing. We propose that the analysis of volatile organic compounds (VOCs) in exhaled breath can be used as a novel, alternative, noninvasive means to monitor glycemia in these patients. Seventeen healthy (9 females and 8 males, 28.0 ± 1.0 yr) and eight type 1 diabetic (T1DM) volunteers (5 females and 3 males, 25.8 ± 1.7 yr) were enrolled in a 240-min triphasic intravenous dextrose infusion protocol (baseline, hyperglycemia, euglycemia-hyperinsulinemia). In T1DM patients, insulin was also administered (using differing protocols on 2 repeated visits to separate the effects of insulinemia on breath composition). Exhaled breath and room air samples were collected at 12 time points, and concentrations of ~100 VOCs were determined by gas chromatography and matched with direct plasma glucose measurements. Standard least squares regression was used on several subsets of exhaled gases to generate multilinear models to predict plasma glucose for each subject. Plasma glucose estimates based on two groups of four gases each (cluster A: acetone, methyl nitrate, ethanol, and ethyl benzene; cluster B: 2-pentyl nitrate, propane, methanol, and acetone) displayed very strong correlations with glucose concentrations (0.883 and 0.869 for clusters A and B, respectively) across nearly 300 measurements. Our study demonstrates the feasibility to accurately predict glycemia through exhaled breath analysis over a broad range of clinically relevant concentrations in both healthy and T1DM subjects.

The changing epidemiology of type 1 diabetes: why is it going through the roof?

The incidence of type 1 diabetes is increasing and this may double the burden of disease in our youngest by 2020. The recent increase in incidence is mostly happening in the very young and those with moderate genetic susceptibility. Many environmental factors have been implicated, but no major determinants have been clearly identified, and the mechanisms of involvement remain elusive. This review summarizes current research efforts directed at understanding the possible reasons for this increase, including the role of viruses, gut microbiota, early life feeding patterns, perinatal factors and childhood growth patterns. It also provides a road map for future research directions.

Coxsackievirus B4 and type 1 diabetes pathogenesis: contribution of animal models

The role of enteroviruses, in particular type B coxsackieviruses (CV-B), in type 1 diabetes (T1D) pathogenesis is supported by epidemiological, clinical and experimental observations.The investigation of T1D pathogenesis benefits from the contribution of animal models called spontaneously diabetic. Among these animals the non-obese diabetic (NOD) mouse and the bio-breeding diabetes-prone (BBDP) rat present a genetic susceptibility manifested by the expression of an autoimmune diabetes similar to the pathology observed in human beings. Other models whose genetic predisposition is less known are of considerable contribution as well. Numerous major observations relative to several aspects of T1D pathogenesis in the context of CV-B infections, such as susceptibility, diabetogenicity, pancreatotropism, mechanisms of beta cells destruction and others, have been deduced thanks to investigations with animal models. Despite their limits, these models are necessary in improving our knowledge of the role of enteroviruses, like CV-B4, in the pathogenesis of T1D, and the recent advances ensuing from their contribution may have important therapeutic and preventive spin-offs.

A genome-wide scan for type 1 diabetes susceptibility genes in nuclear families with multiple affected siblings in Finland

Background

A genome-wide search for genes that predispose to type 1 diabetes using linkage analysis was performed using 900 microsatellite markers in 70 nuclear families with affected siblings from Finland, a population expected to be more genetically homogeneous than others, and having the highest incidence of type 1 diabetes in the world and, yet, the highest proportion in Europe of cases (10%) carrying neither of the highest risk HLA haplotypes that include DR3 or DR4 alleles.

Results

In addition to the evidence of linkage to the HLA region on 6p21 (nominal p = 4.0 × 10^-6), significant evidence of linkage in other chromosome regions was not detected with a single-locus analysis. The two-locus analysis conditional on the HLA gave a maximum lod score (MLS) of 3.1 (nominal p = 2 × 10^-4) on chromosome 9p13 under an additive model; MLS of 2.1 (nominal p = 6.1 × 10^-3) on chromosome 17p12 and MLS of 2.5 (nominal p = 2.9 × 10^-3) on chromosome 18p11 under a general model.

Conclusion

Our genome scan data confirmed the primary contribution of the HLA genes also in the high-risk Finnish population, and suggest that non-HLA genes also contribute to the familial clustering of type 1 diabetes in Finland.

Autism, asthma, inflammation, and the hygiene hypothesis

Inflammation and the genes, molecules, and biological pathways that lead to inflammatory processes influence many important and disparate biological processes and disease states that are quite often not generally considered classical inflammatory or autoimmune disorders. These include development, reproduction, aging, tumor development and tumor rejection, cardiovascular pathologies, metabolic disorders, as well as neurological and psychiatric disorders. This paper compares parallel aspects of autism and inflammatory disorders with an emphasis on asthma. These comparisons include epidemiological, morphometric, molecular, and genetic aspects of both disease types, contributing to a hypothesis of autism in the context of the immune based hygiene hypothesis. This hypothesis is meant to address the apparent rise in the prevalence of autism in the population.

Marked increase in type 1 diabetes mellitus incidence in children aged 0-14 yr in Victoria, Australia, from 1999 to 2002

OBJECTIVES

The objectives of the study were to (i) determine the incidence of type 1 diabetes mellitus (T1DM) in children aged <15 yr in Victoria, Australia, from 1999 to 2002 and (ii) to analyze trends in incidence over this period.

METHODS

Prospective population-based incidence study. The primary source of case ascertainment was from the Australasian Paediatric Endocrine Group (APEG) Victorian diabetes register. The secondary source was the National Diabetes Register (NDR), which ascertains cases from the National Diabetes Service Scheme (NDSS), a Commonwealth government initiative, where patients register to receive diabetes supplies at a subsidized price.

MAIN OUTCOME MEASURES

Age-standardized incidence, trends in incidence by age, sex and year, and variation in incidence by region, season, and socioeconomic status.

RESULTS

Case ascertainment was 99.1% complete using the capture-recapture method. The mean annual age-standardized incidence was 19.3 per 100 000 person years from 1999 to 2002. On average, incidence increased by 9.3% per year, with a greater relative increase in the 0-4 yr age-group (p = 0.037). No gender bias in incidence was found, but the increase in females was statistically significant (13.6% per year, 95% confidence interval 3.7-24.3). Variation in geographical distribution and seasonal onset of incidence was not statistically significant.

CONCLUSIONS

The marked increase in the incidence of T1DM in Victoria is greater than that recently described in other Australia states and developed nations. The etiology of this rise is unclear, while the increased caseload has major implications for diabetes health care providers for current and future resource allocation.