Genetic Risk For Type Research Articles

Genetic Analysis of Krüppel-Like Zinc Finger 11 Variants in 5864 Danish Individuals: Potential Effect on Insulin Resistance and Modified Signal Transducer and Activator of Transcription-3 Binding by Promoter Variant −1659G>C

The transcription factor Krüppel-like zinc finger 11 (KLF11) has been suggested to contribute to genetic risk of type 2 diabetes (T2D). Our previous results showed that four KLF11 variants, in strong linkage disequilibrium (LD block including +185 A>G/Gln62Arg and -1659 G>C) were associated with T2D in a north European case-control study. Here we further analyzed these variants for T2D association in a general Danish population and assess their possible effect on gene function. We genotyped Gln62Arg variant, representative for the LD block, in 5864 subjects of the INTER99 study to assess association to T2D and glucose metabolism-related quantitative traits. We studied effects of LD-block variants on KLF11 function and in particular, the effect of -1659G>C on transcriptional regulation of KLF11 using EMSA, chromatin immunoprecipitation, gene reporter assays, and small interfering RNA transfection. We could not confirm T2D association of the KLF11 LD block, however, in glucose-tolerant subjects; it was significantly associated with higher fasting serum insulin and C-peptide levels and increased homeostasis model assessment insulin resistance indexes (P = 0.00004, P = 0.006, and P = 0.00002, respectively). In addition, binding of signal transducer and activator of transcription (STAT)-3 to the wild-type (-1659G>C) allele stimulated gene transcription, whereas STAT3 did not bind onto the mutant allele. We showed that KLF11 may interfere with glucose homeostasis in a Danish general population and that STAT3-mediated up-regulation of KLF11 transcription was impaired by the -1659G>C variant. Overall, KLF11 variants may have a deleterious effect on insulin sensitivity, although that may not be sufficient to lead to T2D.

Correlation of polymorphism of adiponectin promoter with diabetes type 2 and its complications

objective To explore the correlation of single nucleotide polymorphism (SNP) frequency of adiponectin(APN)in patients with type Ⅱ diabetes(T2DM)and its complications,investigate whether the SNP is a risk factor of inheritance of T2DM,and to set up a highly efficient.accurate, economical and practical screening assay to detect the mutation of APN in clinical practice.Methods According to the diagnostic criteria of T2DM,patients with coronary heart disease(CHD),hypertension (HP),and diabetic nephropathy(NE)were recruited into this study.In simple,12DM group,T2DM-HP, T2DM-CHD.T2DM-NE and the control group.serum biochemistry items are measured.The technique of denaturing high-performance liquid chromatography(DHPLC)was used to detect SNPs of ANP gene.Results After all fragments amplified in the reglen of promoter of APN gene were compared with APN GeneID:9370 sequence recorded in GenBank,point mutation has been identified(-11377G/C).The frequency of genotypes of GG,GC,and CC are 5.16%,42.25%,52.58%and 3.4%.32.75%,63.85%,respectively in the groups of T2DM and control.The frequency of G allele was related to the incidence of T2DM,and is a risk factor of T2DM.The relative risk of GC to CC in developing T2DM is much high than that in the control group (OR=0.55).By comparing the clinical data of different groups of genotype in T2DM,it was observed that the genotype affected systolic blood pressure,BMI,abdominal circumference, and waist-buttock ratio(P=0.015).After optimizing the experimental conditions.it was found column temperature 6 0℃ was the best when using DHPLC technology to estimate SNP of APN gene.Conclusion SNP (-11377G/C) of APN gene G allele has a definite correlation with complications of hypertension in T2DM patients,and may contribute to the genetic risk for type 2 diabetes. Key words: Genes; Diabetes mellitus:Adiponectin

The -759C/T polymorphism of the 5-HT2C receptor is associated with type 2 diabetes in male and female Caucasians

Type 2 diabetes mellitus and obesity constitute serious health problems. Studies reveal that the 5-HT2C receptor contributes substantially to the regulation of a wide variety of behavioral and physiological processes including feeding and glucose homeostasis. Our aim was to determine the possible association of the -759C/T polymorphism of the 5-HT2C receptor gene with type 2 diabetes and obesity in male and female individuals Caucasian origin. The study population consisted of 151 patients diagnosed with type 2 diabetes and 164 nondiabetic patients, all of Greek origin. Genomic DNA was extracted from peripheral blood and analyzed for the -759C/T polymorphism of the 5-HT2C receptor gene using polymerase chain reaction-restriction fragment length polymorphism method. The frequency of T allele of the -759C/T polymorphism of the 5-HT2C receptor was significantly lower in the diabetic group (12.6%) than in the nondiabetic group (23.3%) (P=0.003). The genetic risk of type 2 diabetes for patients not carrying the T allele was increased compared with nondiabetic patients (odds ratio (OR)=2.34, 95% confidence interval (CI)=1.36-4.02). The reduced frequency of T allele was present both in male [10% in patients with diabetes and 21.6% in patients without diabetes (P=0.041)] and female patients [14.1% in patients with diabetes and 24.3% in patients without diabetes (P=0.030)]. In contrast, the frequency of T allele was similar in obese (16.4%) and nonobese (17.1%) patients. Lower frequency of -759T allele of the 5- HT2C receptor gene was associated with type 2 diabetes but not with obesity in male and female Caucasians. Thus, this polymorphism might constitute a prognostic marker for diabetic risk.

Epidemiology and genetic risk of type 1 diabetes among children in Aragon community, Spain

The incidence of type 1 diabetes in children from Aragon (a population of the North of Spain) is reported determining the relations between the onset of type 1 diabetes and gender, age at diagnosis, genetic risk (HLA class II genes) or climatology factors. The population at risk was all 0–14 year-old inhabitants. Patients were identified from five sources: hospitals, primary assistance, endocrinologists, diabetic associations and diabetes camps. The degree of ascertainment was 98.93%. HLA genetic study was performed. Annual incidence was 16.4 per 100,000 per year (95% CI: 14.7–18.2). This incidence was significantly higher in males than in females, 18.7 versus 14.2 ( p < 0.02), and increased with age. The haplotypes (DR3)-DQB1*0201/(DR4)-DQB1*0302 and (DR3)-DQB1*0201/(DR7)-DQB1*0202 conferred the highest risk of type 1 diabetes. A relative high incidence of type 1 diabetes mellitus has been demonstrated in the Northeast of Spain, and it does not support south-to-north incidence gradient in Europe. Haplotypes that conferred a higher risk of disease agree with those founded in other Caucasic populations.

Reduced CCR4, interleukin‐13 and GATA‐3 up‐regulation in response to type 2 cytokines of cord blood T lymphocytes in infants at genetic risk of type 1 diabetes

Aberrancies in T-cell polarization including expression of chemokine receptors have been reported in human leucocyte antigen (HLA) class II associated autoimmune diseases, such as type 1 diabetes (T1D) and rheumatoid arthritis. We asked whether these aberrancies are present at birth in newborn infants carrying the HLA risk haplotypes for T1D. Sixty-seven cord blood (CB) samples from infants were screened for T1D-associated HLA risk genotypes (HLA-DR4-DQ8 and/or DR3-DQ2 without protective alleles). CB lymphocytes were stimulated with phytohaemagglutinin in type 1 (interleukin (IL)-12, anti-IL4) or type 2 (IL-4, anti-IL12) cytokine environment for 6 days. The expression of chemokine and cytokine receptors on T cells was determined by flow cytometry, secretion of cytokines was analysed with enzyme-linked immunosorbent assay, and transcription factors were analysed using real-time reverse transcriptase-polymerase chain reaction. After culture of CB lymphocytes in type 2 cytokine environment newborn infants carrying DR4-DQ8 haplotype (n=18) showed reduced percentage of CD4 T cells expressing CCR4 (P=0 x 009) and the level of CCR4 mRNA was decreased (P=0 x 008). In addition, lower secretion of IL-13 and expression of GATA-3 in CB lymphocytes cultured in type 2 cytokine environment were found in the infants with DR4-DQ8 haplotype (P=0 x 020 and P=0 x 004, respectively) in comparison to newborn infants without DR4-DQ8 and DR3-DQ2 haplotypes (n=37). Poor in vitro induction of type 2 immune responses in newborn infants with DR4-DQ8 haplotype suggests that the HLA genotype associated with risk of autoimmunity may affect the T cell polarization already at birth, which in turn may contribute to the risk for autoimmunity later in life.

Kinetics of Regulatory T Cells Upon Specific Diabetogeneic Activation in a Group of High Risk Relatives of Type 1 Diabetes Mellitus Patients in Comparison with Healthy Controls

Study of defects in function of CD4+CD25+ regulatory T cells in individuals with increased genetic risk for type 1 diabetes (T1D). The autoantigen activation of diabetogenic T cells was significantly higher in high-risk relatives of T1D patients than in healthy controls.

Parental Reactions to Information About Increased Genetic Risk of Type 1 Diabetes Mellitus in Infants

To assess the anxiety, emotions, thoughts, and coping behaviors of parents 1 week after they receive the results of screening of their infant's genetic risk of type 1 diabetes mellitus. Survey. The population-based Type 1 Diabetes Prediction and Prevention project conducted in Turku. Parents of 443 consecutive high-risk infants and 506 next-born low-risk infants. An infant's genetic risk of type 1 diabetes mellitus was measured from cord blood. High-risk information was delivered by telephone and low-risk information by mail 4 weeks later. Anxiety measured using the state anxiety scale of the State-Trait Anxiety Inventory, and feelings, thoughts, and coping behaviors extracted from the questionnaire. One week after obtaining the results, 67% of mothers and 63% of fathers of high-risk children and 58% of mothers and 54% of fathers of low-risk children had returned the questionnaire. Anxiety levels of parents of high-risk infants were similar to those of parents of low-risk infants (P = .86). More than 90% of the parents thought that it was good to know about the risk. Fifty-five percent of mothers and 37% of fathers of high-risk infants expressed modest worry. Increased anxiety was connected with other stressful life events, catastrophizing thoughts of diabetes mellitus risk, and emotion-focused or avoiding coping attitudes. Learning about their infant's genetic diabetes mellitus risk induces only mild anxiety in most parents. Identifying the few parents with stronger anxiety helps focus intensified counseling.

Probiotics for the Prevention of Beta Cell Autoimmunity in Children at Genetic Risk of Type 1 Diabetes—the PRODIA Study

The final aim of the PRODIA study is to determine whether the use of probiotics during the first 6 months of life decreases the appearance of type 1 diabetes mellitus (T1DM)-associated autoantibodies in children with genetic risk for T1DM. A pilot study including 200 subjects was planned to show whether the use of probiotics during the first 6 months of life is safe and feasible. The prevalence of autoantibodies among the study subjects at 6, 12, and 24 months of age was at levels close to the expected and the clinical follow-up did not either indicate problems in the feasibility of the study.

Onset of β‐cell autoimmunity is not associated with elevated concentration of C‐reactive protein in children at genetic risk for Type 1 diabetes

Onset of β‐cell autoimmunity is not associated with elevated concentration of C‐reactive protein in children at genetic risk for Type 1 diabetes

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.

Anti-insulin Activity in IgG-fractions from Children with Newly-diagnosed Type 1 Diabetes and Negative for Insulin Autoantibodies

Insulin autoantibodies (IAA) are often detected as the first humoral sign of β-cell autoimmunity in prospective studies in young children with increased genetic risk of type 1 diabetes. After the appearance of IAA their level typically rise but seems to decline in many cases before the clinical presentation of type 1 diabetes. We hypothesized that the reason for the sudden drops in the levels of IAA could be the formation of immune complexes caused by binding of antibodies to free insulin in plasma.We studied whether isolation of the IgG-fraction and dissociation of immune complexes by acid treatment using protein A column results in the appearance of detectable IAA in those children with newly-diagnosed type 1 diabetes whose plasma samples test negative for IAA. IAA assay was performed in IgG-fractions and corresponding plasma samples from 17 children with type 1 diabetes and 23 unaffected children all testing negative for plasma IAA. The levels of IAA measured from IgG-fractions of diabetic children were higher than the levels of IAA measured from IgG-fractions in the control children ( p=0.004 in Mann–Whitney U-test). Forty-seven percent (8 out of 17) of newly-diagnosed patients negative for plasma IAA before IgG separation had increased levels of IAA in IgG-fractions and only 13% (3 out of 23) of controls. The levels of glutamate decarboxylase autoantibodies (GADA) did not differ between patients (n=14) and controls (n=21) negative for plasma GADA when measured in IgG-fractions. Our results suggest that formation of immune complexes results in false negative results in tests for IAA but not for GADA.

HLA DR phenotypic frequencies and genetic risk of Type 1 diabetes in west region of Algeria, Tlemcen

BackgroundThe main genomic region controlling the predisposition to type 1 diabetes is the Human Leukocyte Antigens (HLA) class II of the major histocompatibility complex. Association with different HLA types depends also on the studied populations. In our investigation, we tried to measure the phenotypic HLA class II association frequencies of DR3 and/or DR4 antigens, using a serologic method called microlymphocytotoxicity analysis, in diabetic and nondiabetic (ND) subjects originating from the west-Algerian region of Tlemcen. The aim of the present study was to determine which HLA DR antigens represent a high susceptibility to develop the disease in this area. Using a case-control retrospective study design, we randomly recruited ninety-one related subjects, 39 type 1 diabetics and 52 ND as controls, at the Internal Medicine Board of Medical Centre University of Tlemcen.ResultsDR3 antigen frequencies were comparable between the type 1 diabetics and the ND subjects and showed no association with the disease (p = 1.000, OR = 0.95), whereas DR4 and DR3DR4 antigens were associated with susceptibility to develop type 1 diabetes (DR4; OR = 2.10, DR3DR4; OR = 1.30). Also, no incidence for DR3 (p = 0.2646) or DR3DR4 (p = 0.0699) antigen frequencies was related to the sex ratio. However, significant differences in HLA DR4 frequencies between type 1 diabetics and ND were found to be related to sex (p = 0.0085).ConclusionTaken together, our investigation showed that the strongest association with type 1 diabetes was noticed in the presence of HLA DR4 antigens followed by DR3DR4 antigens. This study highlighted a characteristic of Tlemcen population; a history of consanguineous marriages. Association studies between the disease and genetic polymorphisms should be undertaken in a population where consanguinity is more limited to reduce confounding in result interpretations.

Prospective assessment in newborns of diabetes autoimmunity (PANDA): maternal understanding of infant diabetes risk.

To assess accuracy of mothers' understanding of their newborns' genetic risk for type 1 diabetes and to identify predictors of the comprehension and retention of genetic information. Mothers of 435 newborns genetically screened at birth were informed of the infant's risk for type 1 diabetes using a standard script that provided both categorical and numerical risk information. The mothers' comprehension and retention of this information were assessed by structured interview on two occasions, approximately 3.6 weeks and approximately 3.9 months postnotification. At the initial interview, 73.1% of mothers gave a correct estimate of their child's genetic risk, 3.2% overestimated risk, 13.3% underestimated risk, and 10.3% could not recall risk at all. At the follow-up interview, fewer mothers (61.9%) correctly estimated their child's risk and more mothers (24.4%) underestimated their child's risk. Maternal accuracy was associated with maternal education, ethnic minority status, infant risk status, maternal ability to spontaneously recall both categorical and numerical risk estimates, and length of time since risk notification. Underestimation of risk was associated with maternal education, family history of diabetes, time since risk notification, and maternal anxiety about the baby's risk. The accuracy of mothers' recall of infant risk declines over time, with an increasing number of mothers underestimating the infant's risk. Effective risk communication strategies need to be developed and incorporated into genetic screening programs.

Humoral beta-cell autoimmunity in relation to HLA-defined disease susceptibility in preclinical and clinical type 1 diabetes.

We have studied the relationship between diabetes-associated autoantibodies and various HLA genotypes and alleles in patients with newly diagnosed type 1 diabetes, in non-diabetic siblings and in children representing the general population to test the hypothesis that specific HLA genes regulate the humoral immune response to various autoantigens. Among the newly diagnosed patients we observed that those carrying the DR4-DQB1*0302 haplotype had increased levels of insulin autoantibodies (IAA) and IA-2 antibodies (IA-2A), but low levels of GAD antibodies (GADA). In contrast, those with the DR3-DQB1*02 haplotype had increased GADA titers but low IAA and IA-2 levels. DQB1*02-homozygous patients had a conspicuously low frequency and low levels of IA-2A. Among the siblings there was an apparent association between genetic risk and the prevalence of islet cell antibodies (ICA), IAA, GADA, IA-2A and multiple autoantibodies, the latter being detectable at a frequency of 24.1% in high risk siblings and at a frequency of only 0.9% in those with genotypes conferring disease protection. Among 7-16-year-old Finnish schoolchildren there was an association between GADA and the DQB1*02/*0302 genotype and the DQB1*0302 allele. Among young children identified from the general population based on high (DQB1*02/0302 heterozygosity) or moderate (DQB1*0302/x; x not equal *02, *0301, *0602, *0603) genetic risk for type 1 diabetes the high risk children seroconverted more often to positivity for ICA, GADA and IA-2A over their first 2 years of life. Among older sibs of these children we observed an obvious relationship between the degree of genetic risk and the frequency of ICA, IAA, GADA, IA-2A, and multiple antibodies. Taken together these observations suggest that HLA genes have a strong impact on the appearance of diabetes-associated autoantibodies both in first-degree relatives of affected children and in the general population. In patients with newly diagnosed disease IA-2A may be a more specific marker of beta-cell damage, whereas GADA might reflect a propensity to autoimmunity in general.

The first signs of beta-cell autoimmunity appear in infancy in genetically susceptible children from the general population: the Finnish Type 1 Diabetes Prediction and Prevention Study.

Little is known about the timing of the etiological events and the preclinical process of type 1 diabetes during the first years of life in the general population. In this population-based prospective birth cohort study, the appearance of diabetes-associated autoantibodies as a sign of beta-cell autoimmunity and the development of type 1 diabetes were monitored from birth. Of 25,983 newborn infants, 2,448 genetically susceptible children were monitored for islet cell antibodies (ICA) at 3- to 6-month intervals. If an infant seroconverted to ICA positivity, all his/her samples were also analyzed for insulin autoantibodies (IAA), antibodies to the 65-kDa isoform of glutamic acid decarboxylase, and antibodies to the protein tyrosine phosphatase-related IA-2 molecule. Fifteen children of those who carried the high-risk genotype (2.7%) and 23 of those who carried the moderate-risk genotype (1.2%; P = 0.019) tested positive for ICA at least once. Among those who showed positivity for at least 2 antibodies during the observation period (25 of 38), IAA appeared as the first or among the first antibodies in 22 children (88%) and emerged earlier than the other antibodies (P < 0.019 or less). The first autoantibodies appeared in the majority of the children in the fall and winter (30 of 38 vs. 8 of 38 in the spring and summer, P < 0.001). These observations suggest that young children in the general population with a strong human-leukocyte-antigen-DQ-defined genetic risk of type 1 diabetes show signs of beta-cell autoimmunity proportionally more often than those with a moderate genetic risk. IAA emerge as the first detectable antibody more commonly than any other antibody specificity, implying that insulin may be the primary antigen in most cases of human type 1 diabetes associated with the DR4-DQB1*0302 haplotype. The seasonal variation in the emergence of the first signs of beta-cell autoimmunity suggests that infectious agents may play a role in the induction of such autoimmunity.

Association of MHC Class I chain-related A (MIC-A) gene polymorphism with Type I diabetes.

A distinct family of MHC genes has been identified in the class III region and denominated MHC Class I chain-related genes (MIC). The MIC-A gene is located between the TNFA and the HLA-B genes. The aim of our study was to test the association of the polymorphism of the MIC-A gene with Type I (insulin-dependent) diabetes mellitus and evaluate the interaction between MIC-A and TNFA, HLA-B, HLA-DR and HLA-DQ gene polymorphism. Type I diabetic (n =95) and healthy (n = 98) Italian subjects were typed for exon 5 of MIC-A and for HLA-DRB1, HLA-DQA1, HLA-DQB1 and TNFA alleles. All subjects were also typed for the presence of HLA-B8 or HLA-B15. The frequency of MIC-A5 was increased in diabetic subjects (53 % vs 15 %) (OR = 6.1) (corrected p, p(c) < 0.0005). Among HLA class II haplotypes, both HLA-DRB1*03-DQA1*0501-DQB1*0201 (DR3-DQ2) and DRB1*04-DQA1*0301-DQB1*0302 (DR4-DQ8) ("at-risk class II haplotypes") were positively associated with diabetes (OR = 6.7 and 6.0, respectively) (p(c) < 0.003). Also HLA-B8 was more frequent among Type I diabetic subjects than among healthy control subjects (OR = 2.8, p = 0.01). None of the TNFA alleles were statistically significantly associated with Type I diabetes. The MIC-A5 exon was negatively associated with age at clinical onset of diabetes (p = 0.012). Thus, 68 % diabetic subjects younger than 25 years and 29 % older than 25 years were carrying this allele. Both MIC-A5 and the at-risk class II haplotypes were independently associated with Type I diabetes and the combined association of the two markers had the highest relative risk (OR = 172). In subjects younger than 25 years, the OR of MIC-A5 was as high as 21.7 and was more than twofold that of at-risk class II haplotypes (OR = 9.5). The MIC-A5 exon was not in linkage disequilibrium with any of the HLA-class I, class II or TNFA alleles studied. The MIC-A gene polymorphism is associated with genetic risk for Type I diabetes and the combination of MIC-A5 and at-risk class II haplotypes is now to be seen as the strongest genetic marker for this disease.