The rs2442598 polymorphism in the ANGPT-2 gene is associated with risk for diabetic retinopathy in patients with type 1 diabetes mellitus in a Brazilian population

ABSTRACT Objective: As studies have reported the involvement of angiopoietin-2 (ANGPT-2) in the pathogenesis of diabetic retinopathy (DR), the aim of this study was to investigate the association between the ANGPT-2 rs2442598 polymorphism and DR. Materials and methods: This case-control study comprised 107 patients with type 1 diabetes mellitus (T1DM) and DR (cases) and 129 patients with T1DM without DR (controls) and with ≥ 10 years of DM. The ANGPT-2 rs2442598 (G/A) polymorphism was genotyped by real-time PCR using TaqMan MGB probes. Results: Genotype distributions of this polymorphism were consistent with the Hardy-Weinberg equilibrium. The frequency of the rs2442598 A allele was higher in cases compared to controls (p = 0.011). Moreover, the A/A genotype was more frequent in cases than in controls (p = 0.017) and was associated with risk for DR after adjustments for duration of DM, HbA1c, triglycerides, estimated glomerular filtration rate, and hypertension (odds ratio [OR] = 5.19, 95% confidence interval [CI] 1.21-22.27). This association was maintained under recessive (OR = 4.78, 95% CI 1.14-19.99) and additive (OR = 6.861, 95% CI 1.45-32.38) inheritance models. Conclusion: Our data demonstrated, for the first time, an association between the ANGPT-2 rs2442598 A allele and risk for DR in T1DM patients from southern Brazil. Additional studies are necessary to replicate this association in other populations.

Implication of epigenetic factors in the pathogenesis of type 1 diabetes / 中华医学杂志(英文版)

Type 1 diabetes (T1D) is an autoimmune disease that resulted from the severe destruction of the insulin-producing β cells in the pancreases of individuals with a genetic predisposition. Genome-wide studies have identified HLA and other risk genes associated with T1D susceptibility in humans. However, evidence obtained from the incomplete concordance of diabetes incidence among monozygotic twins suggests that environmental factors also play critical roles in T1D pathogenesis. Epigenetics is a rapidly growing field that serves as a bridge to link T1D risk genes and environmental exposures, thereby modulating the expression of critical genes relevant to T1D development beyond the changes of DNA sequences. Indeed, there is compelling evidence that epigenetic changes induced by environmental insults are implicated in T1D pathogenesis. Herein, we sought to summarize the recent progress in terms of epigenetic mechanisms in T1D initiation and progression, and discuss their potential as biomarkers and therapeutic targets in the T1D setting.

Clinical features and genetic analysis of a child with late-onset immune dysregulation, polyendocrinopathy, enteropathy, X-Linked syndrome / 中华医学遗传学杂志

OBJECTIVE@#To report on the clinical features and result of genetic testing for a child featuring immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome.@*METHODS@#Clinical records, genetic testing, laboratory investigation and treatment of the child were summarized in addition with a comprehensive review of the literature.@*RESULTS@#The 3-year-old boy was administered due to intractable diarrhea, recurrent infections, liver dysfunction and failure to thrive, though no diabetes or skin disorder was observed. Laboratory testing showed elevated liver enzymes and total IgE, decreased albumin and electrolyte imbalance. Gastrointestinal endoscopy revealed erosion and granules in the duodenum, and edema in the terminal ileum and colon. Biopsies showed villous atrophy in the duodenum and terminal ileum. Genetic testing revealed that the patient has carried a missense c.1087A>G (p.I363V) variant in the exon 10 of the FOXP3 gene. He was treated with enteral and parenteral nutrition, anti infection and Sirolimus, and was waiting for hemopoietic stem cell transplantation.@*CONCLUSION@#Although IPEX syndrome usually occur during infancy, it should not be ruled out solely based on the age, and its presentation can be variable. For male children with refractory diarrhea, autoimmune disorder and growth retardation, the diagnosis should be suspected and confirmed by genetic testing.

Nueva mutación identificada en el gen FOXP3 en lactante menor con diarrea crónica como manifestación de enteropatía autoinmune - síndrome IPEX / New mutation in FOXP3 gene identified in an infant with chronic diarrhea as manifestation of autoinmune enteropathy - IPEX syndrome

INTRODUCCIÓN: El síndrome IPEX (inmunodesregulación, poliendocrinopatía y enteropatía autoinmune ligada a X) causado por mutaciones en el gen FOXP3, se caracteriza por diarrea prolongada, alteraciones endocrinológicas y dermatitis. El tratamiento consiste en la administración de medicamentos inmunosupresores, siendo el trasplante de médula ósea la única cura potencial. OBJETIVO: Describir una nueva mutación del gen FOXP3, así como los hallazgos y evolución de un paciente con síndrome IPEX. CASO CLÍNICO: Lactante menor masculino que debutó al mes de vida con diarrea cró nica, falla intestinal e infecciones recurrentes. Exámenes de laboratorio y biopsia intestinal sugerentes de enteropatía autoinmune. Durante el seguimiento, el paciente presentó refractariedad al manejo inmunosupresor con esteroides, ciclosporina y tacrolimus, falleciendo a los 7 meses de edad por complicaciones vasculares. Antecedente familiar por línea materna de múltiples muertes en hombres menores de 1 año. Ante la sospecha de síndrome IPEX se realizó exoma en trío que reportó una mutación probablemente patogénica en el gen FOXP3. CONCLUSIÓN: Se documentó una nueva mutación del gen FOXP3 en paciente con síndrome IPEX. A pesar de la baja prevalencia de esta enfermedad, es importante el reconocimiento de síntomas no específicos pero sugerentes del diagnóstico.

INTRODUCTION: The IPEX (immune dysregulation, polyendocrinopathy, enteropathy, X-linked) syn drome is caused by the mutations of the FOXP3 gene, characterized by persistent diarrhea, endo crine disorders, and dermatitis. The treatment is the administration of immunosuppressive drugs, where hematopoietic stem cell transplantation is the only potential cure. OBJECTIVE: To describe a new FOXP3 gene mutation, as well as the findings and evolution of a patient with IPEX syndrome. CLINICAL CASE: Male infant presenting at one month of age with chronic diarrhea, intestinal failure, and recurrent infections. Lab tests and intestinal biopsy suggested autoimmune enteropathy. During follow-up, the patient presented resistance to immunosuppressive treatment with corticosteroids, cyclosporine, and tacrolimus, dying at 7 months of age due to vascular complications. He had a ma ternal family history of multiple deaths of men under 1 year of age. IPEX syndrome was suspected therefore a trio whole-exome sequencing was performed that showed a probably pathogenic FOXP3 gene mutation. CONCLUSION: A new FOXP3 gene mutation is reported in a patient with IPEX syndro me. Despite the low prevalence of this disease, it is important to recognize non-specific but suggestive symptoms for its diagnosis.

Identification of key genes for type 1 diabetes mellitus by network-based guilt by association

SUMMARY OBJECTIVE This study aimed to propose a co-expression-network (CEN) based gene functional inference by extending the "Guilt by Association" (GBA) principle to predict candidate gene functions for type 1 diabetes mellitus (T1DM). METHODS Firstly, transcriptome data of T1DM were retrieved from the genomics data repository for differentially expressed gene (DEGs) analysis, and a weighted differential CEN was generated. The area under the receiver operating characteristics curve (AUC) was chosen to determine the performance metric for each Gene Ontology (GO) term. Differential expression analysis identified 325 DEGs in T1DM, and co-expression analysis generated a differential CEN of edge weight > 0.8. RESULTS A total of 282 GO annotations with DEGs > 20 remained for functional inference. By calculating the multifunctionality score of genes, gene function inference was performed to identify the optimal gene functions for T1DM based on the optimal ranking gene list. Considering an AUC > 0.7, six optimal gene functions for T1DM were identified, such as regulation of immune system process and receptor activity. CONCLUSIONS CEN-based gene functional inference by extending the GBA principle predicted 6 optimal gene functions for T1DM. The results may be potential paths for therapeutic or preventive treatments of T1DM.

RESUMO OBJETIVO O objetivo deste estudo é realizar uma inferência funcional genética baseada na rede de coexpressão (CEN), expandindo o escopo do princípio de "Culpa por Associação" (GBA - Guilt by Association) para prever as funções genéticas do diabetes mellitus tipo 1 (T1DM). MÉTODOS Primeiro, os dados transcritos do T1DM foram recuperados do repositório de dados genômicos para a análise dos genes diferenciais (DEGs), e foi gerada uma CEN diferencial ponderada. A área sob a curva ROC (AUC) foi escolhida para determinar a métrica de desempenho para cada termo de Ontologia Genética (GO). A análise da expressão diferencial identificou 325 DEGs no T1DM, e a análise de coexpressão gerou uma CEN diferencial com aresta de peso >0,8. RESULTADOS Um total de 282 anotações de GO com DEGs >20 foram mantidas para inferência funcional. Ao calcular a pontuação de multifuncionalidade dos genes, a inferência da função genética foi realizada para identificar as funções genéticas ideais para T1DM com base na lista de classificação genética ideal. Considerando um valor de AUC >0,7, foram identificadas seis funções genéticas ideais para a T1DM, tais como a regulação do processo imunológico e da atividade dos receptores. CONCLUSÕES A inferência funcional genética baseada em CEN, ao expandir o princípio de GBA, previu seis funções genéticas ideais para o T1DM. Os resultados podem ser caminhos potenciais para tratamentos terapêuticos ou preventivos do T1DM.

The rs11755527 polymorphism in the BACH2 gene and type 1 diabetes mellitus: case control study in a Brazilian population

ABSTRACT Objective Type 1 diabetes mellitus (T1DM) is an autoimmune disorder caused by a complex interaction between environmental and genetic risk factors. BTB domain and CNC homolog 2 (BACH2) gene encodes a transcription factor that acts on the differentiation and formation of B and T lymphocytes. BACH2 is also involved in the suppression of apoptosis and inflammation in pancreatic beta-cells, indicating a role for it in the development of T1DM. Therefore, the aim of this study was to evaluate the association of the BACH2 rs11755527 single nucleotide polymorphism (SNP) with T1DM. Subjects and methods This case-control study comprised 475 patients with T1DM and 598 nondiabetic individuals. The BACH2 rs11755527 (C/G) SNP was genotyped using real-time PCR with TaqMan MGB probes. Results Genotype distributions of rs11755527 SNP were in accordance with frequencies predicted by the Hardy-Weinberg equilibrium in case and control groups and were similar between groups (P = 0.729). The minor allele frequency was 43.6% in cases and 42.5% in controls (P = 0.604). Moreover, the G allele frequency did not differ between groups when considering different inheritance models and adjusting for age, gender, body mass index, and HLA DR/DQ genotypes of high-risk for T1DM. Although, well-known high-risk T1DM HLA DR/DQ genotypes were associated with T1DM in our population [OR= 7.42 (95% CI 3.34 - 17.0)], this association was not influenced by the rs11755527 SNP. Conclusion The BACH2 rs11755527 SNP seems not to be associated with T1DM in a Brazilian population.

Prevalence of markers of celiac disease in Colombian children with diabetes mellitus type 1 / Prevalencia de marcadores de enfermedad celíaca en niños Colombianos con diabetes mellitus tipo 1

Abstract Introduction: Although the association between diabetes mellitus type 1 (T1DM) and celiac disease (CD) is well established; there are only a few studies that focus on South American children, haplotypes and their possible associations. Objective: To determine the prevalence of CD markers in a group of children with T1DM and to analyze the associated clinical, immunological and genetic manifestations. Methods: A prevalence study focusing on children with T1DM who were assessed based on variables including sociodemographics, anthropometric information, disease characteristics, laboratory results and family medical history. In partitipants a positive tTG2 (Ig A anti-transglutaminase), a duodenal biopsy and genotype were performed. The proportion of children with T1DM and CD was estimated (CI 95%). Determinations of central tendency, univariate and bivariate analysis, were also performed; p <0.05 was considered significant. Results: Thirteen (8.4%) of the 155 children (53.6% girls, 11.0 ±3.6 years, 2-18 years) with T1DM were tTG2 positive, four had CD (2.6%), seven had potential CD (4.5%) and nine were HLA DQ2/DQ8 positive (5.8%). Children with T1DM and CD had their last ketoacidotic episode (21.5 ±30.4 months versus 69.5 ±38.8 months, p= 0.0260) earlier than children with T1DM and potential CD. There were no differences with anthropometry or with the laboratory results regarding glycemic control. Conclusions: The prevalence of CD in these children with T1DM is higher than that reported in other South American countries. The prevalence of CD was found to be associated with the time of presentation of T1DM and its main allele, the DQ2/DQ8. These findings are different from what has been described in other places around the world.

Resumen Introducción: A pesar que la asociación entre diabetes mellitus tipo 1 (DMT1) y enfermedad celíaca (EC) está bien establecida; hay pocos estudios en niños suramericanos sobre haplotipos y sus posibles asociaciones. Objetivo: Determinar la prevalencia de marcadores de EC en un grupo de niños con DMT1, analizando las manifestaciones clínicas, inmunológicas y genéticas. Métodos: Estudio de prevalencia en niños con DMT1 a quienes se les tomaron variables sociodemográficas, antropométricas, de la enfermedad, paraclínicas y familiares metabólicas. A los niños con IgA anti-transglutaminasa (tTG2) positivos, se les realizó biopsia duodenal y genotipo. Se estimó la proporción de niños con DMT1 y EC y su IC 95%; medidas de tendencia central, análisis univariado y bivariado, siendo significativa una p <0.05. Resultados: Trece (8.4%) de los 155 niños (53.6% niñas, de 11.0 ±3.6 años, 2-18 años) con DMT1 fueron tTG2 positivos, cuatro presentaron EC (2.6%), siete EC potencial (4.5%) y nueve HLA DQ2/DQ8 (5.8%). Los niños con DMT1 y EC presentaron más pronto su último episodio cetoacidótico (21.5 ±30.4 meses versus 69.5 ±38.8 meses, p= 0.0260) que los niños con DMT1 y EC potencial. No hubo diferencias con la antropometría ni con los paraclínicos del control glicémico. Conclusiones: La prevalencia de EC en estos niños con DMT1 es superior a la de otros países suramericanos; estando asociada al tiempo de presentación de la DMT1 y su principal alelo el DQ2/DQ8, hallazgos diferentes a lo descrito a nivel mundial.

Polimorfismos de un solo nucleótido representativos para los alelos clásicos del antígeno leucocitario humano en familias antioqueñas con diabetes mellitus tipo 1 / Classical HLA alleles tag SNP in families from Antioquia with type 1 diabetes mellitus

Resumen Introducción. La región del antígeno leucocitario humano (Human Leukocyte Antigen, HLA) se ha asociado claramente con enfermedades autoinmunitarias, como la diabetes mellitus de tipo 1. Los polimorfismos representativos de un solo nucleótido (tag Single Nucleotide Polymorphism, tag SNP) constituyen una forma alternativa de evaluar los alelos clásicos del HLA. En la población europea se ha reportado un grupo de tag SNP para múltiples alelos clásicos relacionados con la predisposición o la resistencia frente a dicha enfermedad. Objetivo. Validar la metodología basada en los tag SNP enfocada en la inferencia de alelos HLA clásicos, y evaluar su asociación con la diabetes mellitus de tipo 1 en una muestra de familias antioqueñas. Materiales y métodos. Se estudió una muestra de 200 familias antioqueñas con uno a dos hijos afectados por diabetes mellitus de tipo 1. Se genotipificaron 13 SNP mediante el ARMS-PCR (Amplification Refractory Mutation System-Polymerase Chain Reaction) con cuatro iniciadores, o mediante la PCR-RFLP (PCR-Restriction Fragment Length Polymorphism). Además, se evaluó la validez de los tag SNP de 1.000 genomas reportados en europeos en una muestra de 60 individuos de la población colombiana de Medellín. Se hicieron las pruebas de desequilibrio de la transmisión, de desequilibrio de ligamiento y de equilibrio de Hardy-Weinberg. Resultados. En la población de estudio no se encontró suficiente desequilibrio de ligamiento entre los SNP y los alelos clásicos evaluados, por lo cual no fue posible inferir los alelos clásicos del HLA para el conjunto de familias con diabetes mellitus de tipo 1. El estudio de asociación evidenció que esta región aporta factores tanto de riesgo como de protección para el desarrollo de la enfermedad. Los tag SNP apropiados para la muestra de estudio se determinaron usando los SNP ubicados en la región HLA en la base de datos del 1000 Genomes Project en la mencionada población. Conclusiones. Los patrones de desequilibrio de ligamiento en la población estudiada fueron diferentes a los reportados para la población europea. A pesar de esto, se encontró evidencia clara sobre el papel de la región HLA en el riesgo de padecer diabetes mellitus de tipo 1 en la población de estudio.

abstract Introduction: The HLA region strongly associates with autoimmune diseases, such as type 1 diabetes. An alternative way to test classical HLA alleles is by using tag SNP. A set of tag SNP for several classical HLA alleles has been reported as associated with susceptibility or resistance to this disease in Europeans. Objective: We aimed at validating the methodology based on tag SNP focused on the inference of classical HLA alleles, and at evaluating their association with type 1 diabetes mellitus in a sample of 200 families from Antioquia. Materials and methods: We studied a sample of 200 families from Antioquia. Each family had one or two children with T1D. We genotyped 13 SNPs using tetra-primer ARMS-PCR or PCRRFLP. In addition, we tested the validity of the tag SNP reported for Europeans in 60 individuals from a population of Colombians living in Medellín (CLM) from the 1000 Genomes Project database. Statistical analyses included the Hardy-Weinberg equilibrium, the transmission disequilibrium and the linkage disequilibrium tests. Results: The linkage disequilibrium was low in reported tag SNP and classical HLA alleles in this CLM population. Association analyses revealed both risk and protection factors to develop type 1 diabetes mellitus. Appropriate tag SNPs for the CLM population were determined by using the genotype information available in the 1000 Genome Project database. Conclusions: Although linkage disequilibrium patterns in this CLM population were different from those reported in Europeans, we did find strong evidence of the role of HLA in the development of type 1 diabetes mellitus in the study population.

The low-density lipoprotein receptor-related protein 5 (LRP5) 4037C>T polymorphism: candidate for susceptibility to type 1 diabetes mellitus

ABSTRACT Objective: The present study has investigated the association between low-density lipoprotein receptor-related protein 5 (LRP5) 4037C>T polymorphism and type 1 diabetes mellitus (T1DM) susceptibility in a Brazilian population. Subjects and methods: A total number of 134 T1DM patients and 180 normoglycemic individuals (NG) aged 6-20 years were studied. Glycated hemoglobin and glucose levels were determined. Genotyping of LRP5 4037C>T (rs3736228) was performed. Results: T1DM patients showed poor glycemic control. Genotypes in the codominant (CT: OR = 2.99 [CI 95%: 1.71-5.24], p < 0.001; TT: OR = 5.34 [CI 95%: 1.05-2702], p < 0.001), dominant (CT + TT: OR = 3.16 [CI 95%: 1.84-5.43], p < 0.001) and log-additive (OR = 2.78 [CI 95%: 1.70-4.52], p < 0.001) models, and LRP5 4037T allele (OR = 2.88, [CI 95%: 1.78-4.77], p < 0.001) were associated with an increased risk of developing T1DM. LRP5 4037CT and CT+TT carriers in T1DM group showed higher concentrations of serum glucose and glycated hemoglobin when compared with CC carriers. Conclusion: The LRP5 4037C>T may represent a candidate for T1DM susceptibility, as well as poor glycemic control.

Cinética de muerte de linfocitos en diabetes mellitus tipo 1 y su posible asociación con miR-146a y miR-155 / Kinetics of cell death in type 1 diabetes mellitus and their possible association with miR-146a and miR-155

Aim: Analyze mi-146a and miR-155 expression and its correlation with the apoptosis of lymphocytes T in T1D and control patient. Patients and Methodology: 17 T1D patients (5 children between 8-14 yr and 12 adults between 19-29 yr). Activated and not activated peripheral mononuclear cells were studied were studied. Cellular activation with anti-CD3 and primary culture with interleukyne-2 by 5 days. Apoptosis assays through flow cytometry. miRNA through Taqman probes. Statistical analysis through Kruskal-Wallis and post-hoc Dunn's test. Results: Composition of virgin and memory T CD4 cells showed significant differences for stimulus response in control group (p = 0,0004). Increased memory cells count in control group activated by 7 days than basal (p = 0,0047). For early apoptosis differences were observed in days 3 and 7 with and without activation (p = 0,001). AICD apoptosis showed increases in control group after re-stimulation through TCR (p= 0,03). miR-146a expression was lower in recent-onset T1D children vs recent-onset DM1 adults (p = 0,0167). Conclusion: This study shows a differential miR-146a expression in T1D children with respect to T1D adult patients, diminished AICD mechanism in T1D and altered CD4+CD45RA-CD45R0+ memory cells generation in T1D adult patients.

Search for DQ2 5 and DQ8 alleles using a lower cost technique in patients with type 1 diabetes and celiac disease in a population of southern Brazil

ABSTRACT Objective To evaluate the frequency of DQ2.5 and DQ8 alleles using the Tag-single-nucleotide polymorphism (Tag-SNP) technique in individuals with type 1 diabetes mellitus (T1DM) and celiac disease (CD) in southern Brazil. Materials and methods In a prospective design, we performed the search for DQA1*0501 and DQB1*0201 alleles for DQ2.5 and DQB1*0302 for DQ8 through Real-Time Polymerase Chain Reaction (RT-PCR) technique, using TaqMan Genotyping Assays (Applied Biosystems, USA). The diagnosis of CD was established by duodenal biopsy and genotypic determination performed by StepOne Software v2.3. Allelic and genotypic frequencies were compared between groups using Chi-square and Fisher's exact tests and the multiple comparisons using Finner's adjustment. Results Three hundred and sixty two patients with a median age of 14 years were divided into 3 groups: T1DM without CD (264); T1DM with CD (32) and CD without T1DM (66). In 97% of individuals with T1DM and CD and 76% of individuals with CD without T1DM, respectively, the alleles DQ2.5 and/or DQ8 were identified (p < 0.001). DQ2.5 was more common in individuals with CD (p = 0.004) and DQ8 was more common in individuals with type 1 diabetes (p = 0.008). Conclusions The evaluation of the alleles for DQ2.5 and DQ8 by Tag-SNP technique showed a high negative predictive value among those with T1DM, similar to that described by the conventional technique. The high frequency of DQ8 alleles in individuals with T1DM did not allow differentiating those at higher risk of developing T1DM.

microRNAs y diabetes tipo 1 / microRNAs and type 1 diabetes

The worldwide increased incidence of type 1 diabetes (T1D) and the decreased genotypes that confer increased risk to T1D indicate a strong environmental impact on the disease. These mechanisms could occur through epigenetic modifications that operate on several gene expression patterns (methylation and acetylation, among others). An alternative mechanism of gene expression inhibition are the microRNAs families. These small noncoding RNAs bind the of mRNAs, downregulating and can downregulate the expression of multiple genes. In this review we discussed the role of certain miRNAs in three characteristics observed in T1D, such as inflammation, autoimmunity and apoptosis.

Enfermedades autoinmunitarias asociadas a diabetes mellitus tipo 1A / Autoimmune diseases in type 1A diabetes mellitus

Type 1A diabetes (DM1A) is an autoimmune disease that comprises 10% of patients with diabetes mellitus. Its frequency is gradually increasing in countries like Mexico. Patients with DM1A commonly have hypothyroidism, Addison disease, celiac disease and less common diseases such as polyglandular syndrome. These diseases are related to susceptibility genes such as HLA, CTLA-4 and PTPN22, which induce central and peripheral immunologic tolerance. This review article emphasizes the importance of searching other autoimmune diseases in patients with DM1A, to improve their prognosis and quality of life.

La metilación global del ADN y los niveles de homocisteína en plasma se encuentran disminuidos en pacientes con diabetes mellitus tipo 1 / Global DNA methylation and homocysteine levels are lower in type 1 diabetes patients

Background: The worldwide rise in the incidence of Type 1 Diabetes (T1D), and the concordance rate between monozygotic twins (50%), indicate a strong effect of the environment as an underlying factor of this disease. This process can occur throughout epigenetic modifications of gene expression such as DNA methylation, in which several nutrients participate as cofactors. Aim: To determine DNA methylation status in T1D patients and if it is related to plasma levels of folates and homocysteine (Hcy). Material and Methods: We obtained blood samples from 25 T1D patients aged 13.7 ± 5.9 years (11 males) and 25 healthy subjects aged 31.1 ± 7.8 years (16 males). DNA methylation was measured using a colorimetric kit in extracted DNA. Results are expressed as median (interquartile range). Results: Compared with healthy controls, T1D patients had lower global DNA methylation (0.85 (0.91) % and 1.25 (1.16) % respectively, p < 0.02) and Hcy levels (4.8 (1.1) µmol/L and 7.3 (1.4) µmol/L respectively p < 0.01). There were no differences in folate levels between groups. A significant association between folates and global DNA methylation status was observed in T1D patients (r = -0.564, p < 0.01) and healthy subjects (r = 0.440, p = 0.03). Conclusions: TD1 patients had lower levels of Hcy and global DNA methylation. It is relevant to further investigate if this imbalance also induces epigenetic changes in a gene-specific manner, especially in key genes involved in T1D pathogenesis.

Distribución de polimorfismos del gen del antígeno-4 del linfocito T citotóxico en población chilena con diabetes mellitus tipo 1 / Distribution of cytotoxic T lymphocyte antigen-4 gene polymorphisms in Chilean population with type 1 diabetes mellitus

Background: Cytotoxic T lymphocyte antigen-4 (CTLA-4) molecule is an important regulator of T cell activation involved in the down-regulation of immune response. Their polymorphisms +49 A/G and CT60 have been suggested to confer susceptibility to autoimmune endocrine disorders. The aim of this study was to determine the association of CTLA-4 gene polymorphisms with T1D in the Chilean population. We also wanted to study if the combined haplotypes of +49 A/G and CT60 had an impact on risk for T1D. Methods: To evaluate the impact of allelic variants CT60 and +49 A/G SNPs were studied in a Chilean population, including 248 T1D patients and 160 controls. Genotypes of both polymorphisms of CTLA-4 gene were determinate by PCR-restriction fragment polymorphism (PCRRFLP).Results: No statistical differences were observed when comparing patients with diabetes and controls for both CTLA-4 genotypes. However, the haplotype analysis between CT60 and +49 A/G showed an interesting combination of risk conformed by G*G combination with an OR of 1.648 [1.19- 2.28], (p = 0.002). Conclusions: The G*G haplotype could be a risk marker in patients with T1D in Chilean population.

Thyroid disorders are common in first-degree relatives of individuals with type 1 diabetes mellitus

Objective Thyroid diseases are common in individuals with type 1 diabetes mellitus (T1DM) and should be investigated annually in these individuals. The aim of this study was to evaluate the frequency of thyroid diseases in first degree relatives (FDR) of patients with T1DM. Subjects and methods Eighty individuals (40 patients with T1DM and 40 FDR) were interviewed and blood was sampled for thyroid-stimulating hormone (TSH), free thyroxine (FT4) and thyroid peroxidase (TPO) antibodies measurement. Autoantibodies against glutamic acid decarboxylase 65 (GAD65), islet antigen-2 (IA2) and autoantibodies against insulin (AAI) were measured in FDR. Results We found a similar prevalence of thyroid dysfunction in patients with T1DM and their FDR (22.5% vs. 27.5%; p = 0,79). There were no differences in serum TSH levels (p = 0.29), FT4 (p = 0,45), frequency of abnormal TSH (p = 0.28), positive TPO antibodies (p = 0.13), titers of TPO antibodies (in positive cases) between patients with T1DM and their FDR (p = 0.94). Conclusions Thyroid abnormalities seem to be common not only in patients with T1DM but also in their FDR, which suggests that screening strategies for thyroid diseases might also be useful to these individuals. .

Toll-like receptor 3 (TLR3) and the development of type 1 diabetes mellitus

Type 1 diabetes mellitus (T1DM) is a chronic, progressive autoimmune disease characterized by metabolic decompensation often leading to dehydration and ketoacidosis. Viral agents seem to play an important role in triggering the autoimmune destruction that leads to the development of T1DM. Among several viral strains investigated so far, the enterovirus family has been consistently associated with the onset of T1DM in humans. One of the mediators of viral damage is the double-stranded RNA (dsRNA) generated during replication and transcription of viral RNA and DNA. The Toll-like receptor 3 (TLR3) gene codes for an endoplasmic receptor of the pattern-recognition receptors (PRRs) family that recognizes dsRNA, plays an important role in the innate immune response triggered by viral infection. Binding of dsRNA to the TLR3 triggers the release of proinflammatory cytokines, such as interferons, which exhibit potent antiviral action; thus, protecting uninfected cells and inducing apoptosis of infected ones. Therefore, the TLR3 gene is a good candidate for the development of T1DM. Within this context, the objective of the present review was to address the role of the TLR3 gene in the development of T1DM. Arch Endocrinol Metab. 2015;59(1):4-12.