RESUMO
OBJECTIVES: RNASEH1 gene has recently been associated with type 1 diabetes (T1D) in Colombia. The purpose of this study was to fine mapping the putative functional variant in RNASEH1 and testing its interaction with HLA tagSNPs. METHODS: Two-hundred nuclear families with T1D were included in this study. Probands were tested for GAD65 and IA-2 autoantibodies. Genotyping was performed using 20 coding tagSNPs uncovered through Sanger sequencing (N = 96), in addition to 23 tagSNPs chosen from 1000genomes to cover the extent of the gene region. Also, 45 tagSNPs for classic HLA alleles associated with T1D were also genotyped. The transmission disequilibrium test (TDT) was used to test for association and a multiple testing correction was made using permutation. Interaction between RNASEH1 variants and HLA was evaluated by means of the M-TDT test. RESULTS: We identified 20 variants (15 were novel) in the 96 patients sequenced. None of these variants were in linkage disequilibrium. In total, 43 RNASEH1 variants were genotyped in the 200 families. Association between T1D and rs7607888 was identified (P = .002). Haplotype analysis involving rs7607888 variant revealed even stronger association with T1D (most significative P = .0003). HLA tagSNPs displayed stronger associations (OR = 6.39, 95% CI = 4.33-9.44, P-value = 9.74E-28). Finally, we found several statistically significant interactions of HLA variants with rs7607888 (P-value ranged from 8.77E-04 to 5.33E-12). CONCLUSION: Our results verify the association of rs7607888 in RNASEH1 gene with T1D. It is also shown in the interaction between RNASEH1 and HLA for conveying risk to T1D in Northwest Colombia. Work is underway aiming to identify the actual classic HLA alleles associated with the tagSNPs tested here.
Assuntos
Diabetes Mellitus Tipo 1/genética , Antígenos de Histocompatibilidade Classe II/genética , Polimorfismo de Nucleotídeo Único/genética , Ribonuclease H/genética , Autoanticorpos/sangue , Criança , Pré-Escolar , Colômbia , Diabetes Mellitus Tipo 1/sangue , Diabetes Mellitus Tipo 1/imunologia , Feminino , Haplótipos , Humanos , MasculinoRESUMO
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.
Assuntos
Diabetes Mellitus Tipo 1/genética , Genes MHC da Classe II , Genes MHC Classe I , Antígenos HLA/genética , Polimorfismo de Nucleotídeo Único , Adulto , Alelos , Antígeno CTLA-4/genética , Colômbia/epidemiologia , Simulação por Computador , Diabetes Mellitus Tipo 1/epidemiologia , Epistasia Genética , Feminino , Predisposição Genética para Doença , Genótipo , Humanos , Helicase IFIH1 Induzida por Interferon/genética , Desequilíbrio de Ligação , Masculino , Modelos Genéticos , Proteína Tirosina Fosfatase não Receptora Tipo 22/genéticaRESUMO
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.
Assuntos
Adulto , Feminino , Humanos , Masculino , Genes MHC Classe I , Genes MHC da Classe II , Polimorfismo de Nucleotídeo Único , Diabetes Mellitus Tipo 1/genética , Antígenos HLA/genética , Simulação por Computador , Desequilíbrio de Ligação , Colômbia/epidemiologia , Predisposição Genética para Doença , Diabetes Mellitus Tipo 1/epidemiologia , Alelos , Epistasia Genética , Proteína Tirosina Fosfatase não Receptora Tipo 22/genética , Antígeno CTLA-4/genética , Helicase IFIH1 Induzida por Interferon/genética , Genótipo , Modelos GenéticosRESUMO
Becker's nevus syndrome is part of the epidermal nevus syndromes and has been described with a phenotype that includes Becker's nevus, ipsilateral breast hypoplasia, and variable skeletal malformations. It is more frequent in males than in females (5 : 1) but is more relevant in females. The diagnosis is clinically based and the skin lesion must be present and no other numbered criteria have been established, but with more criteria being present the possibility of the diagnosis is higher. Regarding the treatment of breast hypoplasia, the use of antiandrogen medication has demonstrated adequate clinical response in a dose of 50 mg/day of spironolactone.
RESUMO
BACKGROUND: Protein tyrosine phosphatase, non-receptor type 22 (lymphoid) (PTPN22), cytotoxic T-lymphocyte-associated protein 4 (CTLA4), and interferon induced with helicase C domain 1 (IFIH1) are among the confirmed type 1 diabetes (T1D) susceptibility genes in several populations. The aim of this study was to evaluate the role of PTPN22, CTLA4, and IFIH1 gene variants in the development of T1D in a Colombian population. METHODS: Associations of PTPN22, CTLA4, and IFIH1 variants with T1D were investigated in a sample of 197 nuclear families, including 205 affected children, in the Colombian population. Three to four single nucleotide polymorphisms (SNPs) were analyzed per gene: rs2476600, rs2476601, rs1217418, and rs2488457 for PTPN22; rs1990760, rs3747517, and rs10930046 for IFIH1; and rs231775, rs3087243, and rs231779 for CTLA4. A transmission disequilibrium test was performed for the global sample, in addition to stratified analysis considering autoimmunity, age at onset, and parent of origin. Haplotypes per gene were also analyzed. RESULTS: There was no significant transmission distortion for CTLA4. Conversely, SNPsâ rs10930046 (IFIH1) and rs2476601 (PTPN222) exhibited significant transmission distortion of the C and T alleles, respectively, from parents to affected children (odds ratio [OR] 0.57 and 1.83, respectively). In addition, decreased transmission of the C allele for rs10930046 occurred preferentially from mothers. Stratification analysis revealed that this association was maintained in individuals who were positive for autoantibodies and in those with an age of diagnosis <5 years. CONCLUSION: The results show that IFIH1 and PTPN22 are associated with T1D in Colombian families.
Assuntos
Antígeno CTLA-4/genética , RNA Helicases DEAD-box/genética , Diabetes Mellitus Tipo 1/genética , Predisposição Genética para Doença , Polimorfismo de Nucleotídeo Único/genética , Proteína Tirosina Fosfatase não Receptora Tipo 22/genética , Idade de Início , Alelos , Criança , Colômbia/epidemiologia , Diabetes Mellitus Tipo 1/epidemiologia , Feminino , Genótipo , Haplótipos , Humanos , Helicase IFIH1 Induzida por Interferon , Masculino , Estudos RetrospectivosAssuntos
Cromossomos Humanos Par 2 , Diabetes Mellitus Tipo 1/genética , Ligação Genética , Mapeamento Físico do Cromossomo , Idade de Início , Alelos , Autoantígenos/genética , Colômbia , Feminino , Frequência do Gene , Genes Dominantes , Loci Gênicos , Marcadores Genéticos , Predisposição Genética para Doença , Haplótipos , Humanos , Iodeto Peroxidase/genética , Proteínas de Ligação ao Ferro/genética , Escore Lod , Masculino , Núcleo Familiar , Linhagem , PenetrânciaRESUMO
Hemos encontrado ligamiento y asociación de la diabetes mellitus tipo 1 (T1D) con 2p25. En esta región se halla el gen TPO. Nuestro objetivo fue estudias la asociación de dicho gen con la susceptibilidad a la T1D en un grupo de familias colombianas, todas ellas originarias de Antioquia, una población especial en el noroccidente del país. Se analizaron cien tríos familiares con T1D. Estas familias ya habían sido estudiadas para anticuerpos contra la ácido-glutámico-descarboxilasa (GAD) y el locus marcador D2S319. Para una caracterización adicional se estudió a los probandos para autoanticuerpos contra insulina, tiroperoxidasa (TPO) y fosfatasa de tirosina 2 (IA2). Se estudiaron en TPO dos polimorfismos de un solo nucleótido (SNP): rs4927611 y rs732609. Se escogieron estos marcadores teniendo en cuenta que el polimorfismo cambia el aminoácido codificado y una frecuencia del alelo menor, MFA, ≥ 0,3. La tipificación de los SNP se llevó a cabo mediante la reacción en cadena de la polimerasa-restricción de fragmentos de longitud polimórfica (PCR-RFLP) y el tetraprimer amplification refractory modification system (ARMS-PCR). Los análisis de equilibrio de Hardy-Weinberg (HWE) y de desequilibrio de ligamiento (LD) se hicieron separadamente tanto en los padres como en los probandos. Se estudió la asociación genética por medio de la prueba de desequilibrio de la transmisión (TDT). Encontramos que 86% de los pacientes presentaban al menos uno de los tres autoanticuerpos estudiados. Tanto los probandos como sus padres se encontraron en equilibrio de Hardy-Weinberg para ambos SNP. Además, los dos marcadores se encontraron en estrecho desequilibrio de ligamiento (LD) (p < 0,0001). Se identificó un haplotipo asociado con susceptibilidad a la enfermedad (p = 0,0116). Se halló autoinmunidad en una proporción similar a la previamente informada. Se encontró que un haplotipo en el gen TPO está asociado con la enfermedad. Tal haplotipo se caracteriza por los alelos G y A en los SNP rs4927611 y rs732609, respectivamente. Nuestros resultados sugieren una posible participación causal del gen TPO en la T1D. Para verificarlos, se está recolectando una muestra de similar tamaño en la misma población colombiana.
We have found linkage and association of type 1 diabetes (T1D) to 2p25. The TPO gene lies within this region. Our aim was to test the association of this gene with the susceptibility to T1D in a group of Colombian families, all of them originated in Antioquia, a special population in northwestern Colombia. One hundred familial trios with type 1 diabetes (T1D) were analyzed. They had already been studied for anti-glutamic acid descarboxilase (GAD) antibodies and the marker locus D2S319. For further characterization, the probands were tested for autoantibodies against insulin, TPO and thyrosine phosphatase 2 (IA-2). Two single nucleotide polymorphisms (SNPs) (rs4927611 and rs732609) were tested in TPO. These two markers were chosen considering that the polymorphism changes the encoded amino-acid and a minor allele frequency, MAF, ≥ 0.3. SNP typing was carried out by means of the polymerase chain reaction/restriction fragment length polymorphisms (PCR-RFLP)and the tetraprimer amplification refractory mutation system (ARMS-PCR) methods. Hardy-Weinberg equilibrium (HWE) and linkage disequilibrium (LD) analyses were separately tested on both parents and probands. Genetic association was tested by the transmission disequilibrium test (TDT). It was found that 86% of the patients presented at least one of the three auto-antibodies tested. Bothparents and probands were found in HWE for both SNPs. In addition, the two markers were found in tight LD (p < 0.0001). A haplotype associated with susceptibility to the disease was identified (p = 0.0116). Autoimmunity was found in a proportion similar to that previously reported. It was found that a haplotype at TPO gene is associated with the disease. Such haplotype is characterized by alleles G and A at rs4927611 and rs732609 SNPs, respectively. Our results suggest a possible causative participation of the TPO gene in T1D. In order to verify them, a sample of equivalent size is currently being collected, from the same population in Colombia.
Assuntos
Humanos , Diabetes Mellitus/genética , Genética/estatística & dados numéricosRESUMO
Las enfermedades complejas se caracterizan porque presentan varios genes además de factores ambientales implicados en su etiología. Las bases genéticas de la diabetes mellitus tipo 1 (T1D) supone un efecto mayor del complejo HLA que interactúa con otros genes y con el ambiente. Mucho se ha descrito acerca de la posible participación de las infecciones virales como desencadenadores de T1D. En esta revisión exploramos los posibles mecanismos por los cuales el gen RNASEH1 podría estar participando en la etiología de T1D, a partir de una infección viral. El gen RNASEH1 se localiza en la región cromosómica 2p25, la cual ha sido recientemente implicada por nosotros en la susceptibilidad a T1D. Este gen ha sido implicado en la enfermedad mediante análisis genético. Acá pretendemos dar sentido biológico a los datos genéticos. Considerando que la enfermedad es multifactorial, este planteamiento no excluye la participación de otros genes u otros factores ambientales.
Complex disorders are characterized by presenting many genes and other environmental factors implicated in their etiology. The genetic bases of type 1 diabetes mellitus (T1D) suppose a major effect of the HLA complex which interacts with other genes and the environment. Much has been written about the possible implication of viral infections as triggers of T1D. This review explores the mechanisms by which the RNASEH1 gene could be involved in the etiology of T1D, due to a viral infection. The RNASEH1 gene is located in chromosome 2p25, which has been recently implicated in the susceptibility to T1D by the authors, through genetic analysis.This text hopes to establish a biological context for the genetic data. Taking into account that this is a multifactorial disease, this approach does not exclude the eventual participation of other genes or environmental factors.
Assuntos
Diabetes Mellitus Tipo 1 , Predisposição Genética para DoençaRESUMO
The frequency and functionality of peripheral blood invariant (iNKT) cells and their subsets, as well as other regulatory T-cell subsets, were evaluated in patients with type 1A diabetes mellitus (DM1), Hashimoto's disease, and Graves' disease. In addition to healthy individuals (HC), patients with type 2 diabetes mellitus (DM2) were included as controls because this disease has a different physiopathology. A similar frequency of total iNKT cells, as well as their subsets, existed among HC and the different study groups. Similar results were reported when we compared the frequency of CD4(+)/CD25(high) T cells, CD8(+)/CD28(negative) T cells, and gamma-delta T cells among HC and study groups, whereas patients with DM2 exhibited a higher frequency of CD8(+)/CD28(negative) T cells compared with HC and DM1. Also, patients with DM2 exhibited a lower frequency of CD4(negative) and CD4(+) iNKT cells expressing tumor necrosis factor-alpha (TNF-alpha) than HC. We did not observe significant differences in the frequency of iNKT cells expressing interleukin-4 or interferon-gamma among study groups and controls. Our findings support a normal frequency and function of peripheral blood iNKT cells in different endocrine autoimmune diseases, but an abnormal expression of TNF-alpha by circulating iNKT cells from patients with DM2.
Assuntos
Diabetes Mellitus Tipo 1/sangue , Células Matadoras Naturais/metabolismo , Doenças da Glândula Tireoide/sangue , Adulto , Colômbia , Diabetes Mellitus Tipo 1/patologia , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/patologia , Feminino , Citometria de Fluxo , Doença de Graves/sangue , Doença de Graves/patologia , Humanos , Interferon gama/sangue , Interleucina-4/sangue , Células Matadoras Naturais/patologia , Contagem de Linfócitos , Masculino , Pessoa de Meia-Idade , Doenças da Glândula Tireoide/patologia , Fator de Necrose Tumoral alfa/sangue , Adulto JovemRESUMO
El síndrome de Allgrove fue descrito en 1978 por Allgrove et al. como una entidad familiar de origen desconocido caracterizada por deficiencia aislada de glucorticoides, acalasia esofágica y producción defectuosa de lágrimas, por lo que ha sido denominado síndrome triple AAA (adrenal insufficiency, achalasia, alacrima); por lo general aparece durante la primera década de la vida con disfagia o con crisis suprarrenal severa; son pocos los casos diagnosticados de novo en los adultos en quienes predominan síntomas autonómicos y manifestaciones neurológicas como retardo mental, hiperreflexia, voz nasal, anisocoria, ataxia, hipotensión postural y disfunción sexual. En la consulta de Endocrinología Pediátrica del Hospital Universitario San Vicente de Paúl de Medellín se han identificado 5 pacientes con las características clínicas propias del síndrome. Todos mostraron alacrimia e insuficiencia suprarrenal y sólo en uno de los pacientes la acalasia aún no se ha diagnosticado pero la sintomatología que presenta es muy sugestiva de la misma; la alteración neurológica más común en esta serie es el retraso mental. La edad media de aparición de la alacrimia es 3.8 años, de la insuficiencia suprarrena 4.7 años y de la acalasia 7.2 años. Un hallazgo interesante y poco informado es el hipotiroidismo, que es subclínico en tres pacientes, permanente en uno y transitorio en otro.
The Allgrove syndrome (also known as Triple A syndromes), was described by Allgrove et al. in 1978 as a familiar clinical entity of unknown etiology whose characteristic features are adrenal insufficiency, achalasia and alacrima. The usual presentation is during the first 10 years of life with dysphagia or severe adrenal insufficiency, few new cases have been discovered in adults, whose autonomic symptoms and neurological manifestations such as mental retardation, hyperreflexia, nasal speech, anisocoria, ataxia, postural hypotension and sexual dysfunction are predominant. At the Pediatric Endocrinology Service of Hospital Universitario San Vicente de Paúl, Medellín, Colombia, 5 patients have been identified with the clinical features of Allgrove syndrome. All patients have showed both alacrima and adrenal insufficiency. Achalasia has not been diagnosed in one patient, whose symptomatology is highly suggestive to the syndrome. Mental retardation is the most frequent neurological alteration seen. The mean age of presentation for alacrima was 3.8 years, for adrenal insufficiency was 4.7 years and for achalasia was 7.2 years. An interesting finding and occasionally reported is the presence of hypothyroidism, which is subclinic in three patients, transient hypothyroidism in one patient and clinical hypothyroidism in the other one.