Jorma Ilonen

Jorma Ilonen
University of Turku | UTU · Institute of Biomedicine

About

821
Publications
56,711
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31,554
Citations
Citations since 2017
169 Research Items
12842 Citations
201720182019202020212022202305001,0001,5002,0002,500
201720182019202020212022202305001,0001,5002,0002,500
201720182019202020212022202305001,0001,5002,0002,500
201720182019202020212022202305001,0001,5002,0002,500
Introduction
Skills and Expertise

Publications

Publications (821)
Article
The association between HLA genotypes and type 1 diabetes is well known. We set out to examine incidence rates and ratios of type 1 diabetes depending on the risk afflicted by HLA genotype. Children with the high-risk genotype have a 45-fold disease risk compared to peers with neutral or protective genotypes.
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Background: Participants' study satisfaction is important for both compliance with study protocols and retention, but research on parent study satisfaction is rare. This study sought to identify factors associated with parent study satisfaction in The Environmental Determinants of Diabetes in the Young (TEDDY) study, a longitudinal, multinational...
Article
To exemplify autoimmune-associated genetic influence on the colonization of bacteria frequently used in probiotics, microbial composition of stool from 1326 one-year-old infants was analyzed in a prospective general-population cohort, All Babies In Southeast Sweden (ABIS). We show that an individual's HLA haplotype composition has a significant imp...
Article
Aim: To determine the association of HLA class II risk with the demographic and clinical characteristics of type 1 diabetes at diagnosis. Methods: We conducted a register-based retrospective cohort study of 4993 Finnish children (2169 girls)-diagnosed with type 1 diabetes under the age of 15 years in 2003-2016. The participants were divided into...
Article
The perinatal period represents a critical window for cognitive and immune system development, promoted by maternal and infant gut microbiomes and their metabolites. Here, we tracked the co-development of microbiomes and metabolomes from late pregnancy to 1 year of age using longitudinal multi-omics data from a cohort of 70 mother-infant dyads. We...
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Aims/hypothesis Monogenic forms of diabetes (MODY, neonatal diabetes mellitus and syndromic forms) are rare, and affected individuals may be misclassified and treated suboptimally. The prevalence of type 1 diabetes is high in Finnish children but systematic screening for monogenic diabetes has not been conducted. We assessed the prevalence and clin...
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Purpose The aim was to study the associations between dietary intake of fatty acids in childhood and the risk of islet autoimmunity and type 1 diabetes (T1D). Methods The prospective Finnish Type 1 Diabetes Prediction and Prevention (DIPP) Study included children with genetic susceptibility to T1D born between 1996 and 2004. Participants were foll...
Article
Objectives: The Environmental Determinants of Diabetes in the Young (TEDDY) study follows an HLA-risk selected birth cohort for celiac disease (CD) development using a uniform protocol. Children under investigation come from 6 different regions within Europe and the United States. Our aim was to identify regional differences in celiac disease auto...
Article
OBJECTIVE To distinguish among predictors of seroconversion, progression to multiple autoantibodies and from multiple autoantibodies to type 1 diabetes in young children. RESEARCH DESIGN AND METHODS Genetically high-risk newborns (n = 8,502) were followed for a median of 11.2 years (interquartile range 9.3–12.6); 835 (9.8%) developed islet autoant...
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Background Anatomic variation or early differences in glucose metabolism have been linked to the development of type 1 diabetes. We aimed to describe early glucose metabolism based on HbA1c, oral glucose tolerance test (OGTT), and random plasma glucose years before the presentation of type 1 diabetes in five risk groups based on autoantibody combin...
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OBJECTIVE Biomarkers predicting risk of type 1 diabetes (stage 3) among children with islet autoantibodies are greatly needed to prevent diabetic ketoacidosis and facilitate prevention therapies. RESEARCH DESIGN AND METHODS Children in the prospective The Environmental Determinants of Diabetes in the Young (TEDDY) study (n = 707) with confirmed di...
Preprint
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In many populations, the peak period of incidence of type 1 diabetes (T1D) has been observed to be around 10–14 years of age, coinciding with puberty, but direct evidence of the role of puberty in the development of T1D is limited. We therefore aimed to investigate whether puberty and the timing of its onset are associated with the development of i...
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Aims/hypothesis Enteroviral infection has been implicated consistently as a key environmental factor correlating with the appearance of autoimmunity and/or the presence of overt type 1 diabetes, in which pancreatic insulin-producing beta cells are destroyed by an autoimmune response. Genetic predisposition through variation in the type 1 diabetes r...
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Objective: Subtypes in type 1 diabetes pathogenesis have been implicated based on the first appearing autoantibody (primary autoantibody). We set out to describe the glucose metabolism in preclinical diabetes in relation to the primary autoantibody in children with HLA-conferred disease susceptibility. Design and Methods: Dysglycemic markers were d...
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Aims/hypothesis Distinct DNA methylation patterns have recently been observed to precede type 1 diabetes in whole blood collected from young children. Our aim was to determine whether perinatal DNA methylation is associated with later progression to type 1 diabetes. Methods Reduced representation bisulphite sequencing (RRBS) analysis was performed...
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Human torque teno viruses (TTVs) are a diverse group of small nonenveloped viruses with circular, single-stranded DNA genomes. These elusive anelloviruses are harbored in the blood stream of most humans and have thus been considered part of the normal flora. Whether the primary infection as a rule take(s) place before or after birth has been debate...
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The non-HLA loci conferring susceptibility to type 1 diabetes determine approximately half of the genetic disease risk, and several of them have been shown to affect immune-cell or pancreatic β-cell functions. A number of these loci have shown associations with the appearance of autoantibodies or with progression from seroconversion to clinical typ...
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Background Current evidence suggests that the composition of infant formula (IF) affects the gut microbiome, intestinal function, and immune responses during infancy. However, the impact of IF on circulating lipid profiles in infants is still poorly understood. The objectives of this study were to (1) investigate how extensively hydrolyzed IF impac...
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Objective: The pathogenesis of type 1 diabetes (T1D) is associated with genetic predisposition and immunological changes during presymptomatic disease. Differences in immune cell subset numbers and phenotypes between T1D patients and healthy controls have been described; however, the role and function of these changes in the pathogenesis is still...
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Background High gluten intake is associated with increased risk of celiac disease (CD) in children at genetic risk. Objectives To investigate if different dietary gluten sources up to age two years confer different risks of celiac disease autoimmunity (CDA) and CD in children at genetic risk. Design Three-day food records were collected at age si...
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Objectives: We aimed to further characterize demography and genetic associations of type 1 diabetes "endotypes" defined by the first appearing islet specific autoantibodies. Research design and methods: We analyzed 3277 children diagnosed before the age of 10 years from the Finnish Pediatric Diabetes Register. The most likely first autoantibody...
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The Environmental Determinants of Diabetes in the Young (TEDDY) study enrolled 8676 children, 3–4 months of age, born with HLA-susceptibility genotypes for islet autoimmunity (IA) and type 1 diabetes (T1D). Whole-genome sequencing (WGS) was performed in 1119 children in a nested case–control study design. Telomere length was estimated from WGS data...
Article
OBJECTIVE Previous findings suggest that there are age-related endotypes of type 1 diabetes with different underlying etiopathological mechanisms in those diagnosed at age <7 years compared with those diagnosed at age ≥13 years. We set out to explore whether variation in demographic, clinical, autoimmune, and genetic characteristics of children and...
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Aim: We tested the hypothesis of a more aggressive disease process at diagnosis of type 1 diabetes during fall and winter, the colder seasons with consistently observed higher incidence of type 1 diabetes. Methods: Seasonality in the manifestation of type 1 diabetes was examined in 4993 Finnish children and adolescents. Metabolic characteristics...
Article
Objective: The Environmental Determinants of Diabetes in the Young (TEDDY) study is uniquely capable of investigating age-specific differences associated with type 1 diabetes. Because age is a primary driver of heterogeneity in type 1 diabetes, we sought to characterize by age metabolic derangements prior to diagnosis and clinical features associa...
Article
Objectives: The association between human leukocyte antigen (HLA) class II genotypes and susceptibility to type 1 diabetes (T1D) is well established. This study aimed at examining whether there are differences in the presentation of T1D depending on the HLA genotype. Research design and methods: We divided the study participants (N = 5798) in th...
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Significant progress has been made in elucidating genetic risk factors influencing Type 1 diabetes (T1D); however, features other than genetic variants that initiate and/or accelerate islet autoimmunity that lead to the development of clinical T1D remain largely unknown. We hypothesized that genetic and environmental risk factors can both contribut...
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Objective Growth-based determination of pubertal onset timing would be cheap and practical. We aimed to determine this timing based on pubertal growth markers. Secondary aims were to estimate the differences in growth between cohorts and identify the role of overweight in onset timing. Design This multicohort study includes data from three Finnish...
Article
Cow’s milk allergy (CMA) is one of the earliest manifestations of allergic diseases. Early dietary factors, like maternal diet during pregnancy, may play a role in the development of allergic diseases in the offspring. We aimed to investigate the association between maternal intake of fatty acids during pregnancy and the risk of CMA in the offsprin...
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Objective To evaluate the role of autoantibodies to N-terminally truncated glutamic acid decarboxylase GAD65(96–585) (t-GADA) as a marker for type 1 diabetes (T1D) and to assess the potential HLA-associations with such autoantibodies. Design In this cross-sectional study combining data from the Finnish Pediatric Diabetes Register, the Type 1 Diabe...
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In studies following selective sampling protocols for secondary outcomes, conventional analyses regarding their appearance could provide misguided information. In the large type 1 diabetes prevention and prediction (DIPP) cohort study monitoring type 1 diabetes-associated autoantibodies, we propose to model their appearance via a multivariate frail...
Article
Background Consumption of unprocessed cow’s milk has been associated with a lower risk of childhood asthma and/or atopy. Not much is known about differently processed milks. We aimed to study the association between the consumption of differently processed milk products and asthma risk in a Finnish birth cohort. Methods We included 3053 children f...
Preprint
Full-text available
We tested the hypothesis of a more aggressive disease process at diagnosis of type 1 diabetes during autumn and winter, the colder seasons with consistently observed higher incidence of type 1 diabetes, compared to spring and summer. Seasonality in the manifestation of type 1 diabetes was examined in 4993 Finnish children and adolescents participat...
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Aims/hypothesis The β-cell stress hypothesis suggests that increased insulin demand contributes to the development of type 1 diabetes. In the TRIGR trial we set out to assess the profile of plasma glucose and HbA1c before the diagnosis of clinical diabetes compared to nondiabetic children. A cohort of children (N = 2159) with an affected first-degr...
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Background Decreased exposure to microbial agents in industrialized countries and urban living areas is considered as a risk factor of developing immune-mediated diseases, such as allergies and asthma. Epithelial surfaces in the gastrointestinal and respiratory tracts and in the skin constitute the primary areas in contact with the environmental mi...
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Objectives: To assess whether weaning to an extensively hydrolyzed formula (EHF) decreases gut permeability and/or markers of intestinal inflammation in infants with HLA-conferred diabetes susceptibility, when compared with conventional formula. Study design: By analyzing 1468 expecting biological parent pairs for HLA-conferred susceptibility fo...
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Background Enterovirus (EV) infections, being among the most prevalent viruses worldwide, have been associated with reduced risk of allergic diseases. We sought to determine the association of EVs with allergic sensitization and disease in early childhood. Methods The study was carried out in a nested case-control setting within a prospective birt...
Article
Genes in the HLA class II region include the most important inherited risk factors for type 1 diabetes (T1D) although also polymorphisms outside the HLA region modulate the predisposition to T1D. This study set out to confirm a recent observation in which a novel expression quantitative trait locus was formed by three single nucleotide polymorphism...
Article
OBJECTIVE To combine prospective cohort studies, by including HLA harmonization, and estimate risk of islet autoimmunity and progression to clinical diabetes. RESEARCH DESIGN AND METHODS For prospective cohorts in Finland, Germany, Sweden, and the U.S., 24,662 children at increased genetic risk for development of islet autoantibodies and type 1 di...
Preprint
The earliest predictors of future autoimmune diseases are a series of autoantibodies that are rarely evaluated and very within and between diseases. In addition, autoantibodies often appear just prior to disease onset. All of these factors make it difficult to apply interventions that might prevent disease. Earlier predictors of disease are needed....
Preprint
Full-text available
Distinct DNA methylation patterns have recently been observed to precede type 1 diabetes in whole blood collected from young children. Our aim was to determine, whether perinatal DNA methylation could be associated with later progression to type 1 diabetes. Reduced representation bisulfite sequencing (RRBS) analysis was performed on umbilical cord...
Article
Full-text available
Objective: Environmental microbial exposures have been implicated to protect against immune-mediated diseases such as type 1 diabetes. Our objective was to study the association of land cover around the early-life dwelling with the development of islet autoimmunity and type 1 diabetes to evaluate the role of environmental microbial biodiversity in...
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Narcolepsy type 1 (NT1) is a chronic neurological disorder having a strong association with HLA-DQB1*0602, thereby suggesting an immunological origin. Increased risk of NT1 has been reported among children or adolescents vaccinated with AS03 adjuvant-supplemented pandemic H1N1 influenza A vaccine, Pandemrix. Here we show that pediatric Pandemrix-as...
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Our aim was to study the associations between maternal vitamin C and iron intake during pregnancy and the offspring’s risk of developing islet autoimmunity and type 1 diabetes. The study was a part of the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) prospective birth cohort including children genetically at risk of type 1 diabetes born...
Article
Objective We examined parental diabetes monitoring behaviors in a cohort of children at increased genetic risk for type 1 diabetes. We hypothesized that being informed of a positive islet autoantibody (IA) would increase monitoring behaviors. Methods The Environmental Determinants of Diabetes in the Young (TEDDY) study follows 8676 children with h...
Preprint
Background: Enterovirus (EV) infections, being among the most prevalent viruses worldwide, have been associated with reduced risk of allergic diseases. We sought to determine the association of EVs with allergic sensitization and disease in early childhood. Methods: The study was carried out in a nested case-control setting within a prospective bir...
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Full-text available
Aims/hypothesis Shared aetiopathogenetic factors have been proposed in type 1 diabetes and type 2 diabetes and both diseases have been shown to cluster in families. Characteristics related to type 2 diabetes have been described in patients with type 1 diabetes with a positive family history of type 2 diabetes. We wanted to characterise the family h...
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The genes of the Major Histocompatibility Complex (MHC), which plays a fundamental role in the immune system, are some of the most diverse genes in vertebrates and have been connected to mate choice in several species, including humans. While studies suggest a positive relationship between MHC diversity and male facial attractiveness, the connectio...
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Early childhood infections have been implicated in the development of immune-mediated diseases, such as allergies, asthma, and type 1 diabetes. We set out to investigate the immunomodulatory effects of early viral infections experienced before the age of one year on the peripheral regulatory T cell population (Treg) and circulating cytokines in a b...
Article
Introduction: In childhood, the so-called allergic march involves progression from IgE sensitization to allergy-related symptoms. Both IgE sensitization and relevant clinical symptoms are required for the diagnosis of allergy, but concordance between test results and clinical symptoms varies greatly, creating challenges for the diagnostics and for...
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Full-text available
Enterovirus and adenovirus infections have been linked to the development of celiac disease. We evaluated this association in children who developed biopsy-proven celiac disease (N = 41) during prospective observation starting from birth, and in control children (N = 53) matched for the calendar time of birth, sex, and HLA-DQ genotype. Enterovirus...
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Aims/hypothesis The aim of this work was to examine the relationship between family history of type 1 diabetes, birthweight, growth during the first 2 years and development of multiple beta cell autoantibodies in children with a first-degree relative with type 1 diabetes and HLA-conferred disease susceptibility. Methods In a secondary analysis of...
Article
Most patients with celiac disease are positive for either HLA-DQA1*05: 01-DQB1*02 (DQ2.5) or DQA1*03:01-DQB1*03:02 (DQ8). Remaining few patients are usually DQA1*02:01-DQB1*02 (DQ2.2) carriers. Screenings of populations with high frequencies of these HLA-DQA1-DQB1 haplotypes report a 1% to 3% celiac disease prevalence. The aim was to determine the...
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Context: We set out to characterize the dynamics of islet autoantibodies over the first 15 years of life in children carrying genetic susceptibility to type 1 diabetes (T1D). We also assessed systematically the role of zinc transporter 8 autoantibodies (ZnT8A) in this context. Design: HLA-predisposed children (N = 1006, 53.0% boys) recruited fro...
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Aims/hypothesis Mucosal-associated invariant T (MAIT) cells are innate-like T cells that recognise derivatives of bacterial riboflavin metabolites presented by MHC-Ib-related protein 1 (MR1) molecules and are important effector cells for mucosal immunity. Their development can be influenced by the intestinal microbiome. Since the development of typ...
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In the last decade, increasing incidence of type 1 diabetes (T1D) stabilized in Finland, a phenomenon that coincides with tighter regulation of perfluoroalkyl substances (PFAS). Here, we quantified PFAS to examine their effects, during pregnancy, on lipid and immune-related markers of T1D risk in children. In a mother-infant cohort (264 dyads), hig...
Article
Cow's milk allergy (CMA) is the most common food allergy in young children and it is often the first manifestation of atopic diseases. Accordingly, very early environmental factors, such as maternal diet during pregnancy, may play a role in the development of CMA, but the evidence is limited. The aim of this study was to investigate the association...
Article
Full-text available
Objective: The aim of this study was to explore the extended family history of type 1 diabetes in children at genetic risk and define the impact of a positive family history on the development of islet autoimmunity and type 1 diabetes. Methods: The subjects were participants in The Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study a...
Article
Background: High dietary intake of nitrate and nitrite might increase the risk of type 1 diabetes. To our knowledge, no earlier prospective study has explored whether maternal dietary intake of nitrate and nitrite during pregnancy is associated with the risk of type 1 diabetes in the offspring. Objective: Our aim was to study association between...
Article
Full-text available
Type 1 diabetes (T1D)—an autoimmune disease that destroys the pancreatic islets, resulting in insulin deficiency—often begins early in life when islet autoantibody appearance signals high risk1. However, clinical diabetes can follow in weeks or only after decades, and is very difficult to predict. Ketoacidosis at onset remains common2,3 and is most...
Article
Objective We aimed to clarify the association of various HLA risk alleles with different types of autoantibodies initiating islet specific autoimmunity. Methods Follow‐up cohorts from the Finnish Type 1 Diabetes Prediction and Prevention (DIPP) study and children diagnosed with type 1 diabetes from the Finnish Pediatric Diabetes Register (FPDR) we...
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Full-text available
Celiac disease (CD) is a systemic immune-mediated disorder with increased frequency in the developed countries over the last decades implicating the potential causal role of various environmental triggers in addition to gluten. Herein, we apply determination of perfluorinated alkyl substances (PFAS) and combine the results with the determination of...
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Aims/hypothesisPrevious metabolomics studies suggest that type 1 diabetes is preceded by specific metabolic disturbances. The aim of this study was to investigate whether distinct metabolic patterns occur in peripheral blood mononuclear cells (PBMCs) of children who later develop pancreatic beta cell autoimmunity or overt type 1 diabetes.Methods In...
Article
Aims Type 1 diabetes (T1D) is an autoimmune disease that affects many children worldwide. Genetic factors and environmental triggers play crucial interacting roles in the aetiology. This study aimed to assess the contribution of HLA‐DRB1‐DQA1‐DQB1 alleles, haplotypes, and genotypes to the risk of T1D among Saudis. Methods A total of 222 children w...
Preprint
OBJECTIVES Celiac disease (CD) is a systemic immune-mediated disorder with increased frequency in the developed countries over the last decades implicating the potential causal role of various environmental triggers in addition to gluten. Herein, we apply determination of perfluorinated alkyl substances (PFAS) and combine the results with the deter...
Article
Full-text available
Dysfunction of FOXP3-positive regulatory T cells (Tregs) likely plays a major role in the pathogenesis of multiple autoimmune diseases, including type 1 diabetes (T1D). Whether genetic polymorphisms associated with the risk of autoimmune diseases affect Treg frequency or function is currently unclear. Here, we analysed the effect of T1D-associated...