Asthma: Gln27glu And Arg16gly Polymorphisms Of The Beta2-adrenergic Receptor Gene As Risk Factors.

Asthma is caused by both environmental and genetic factors. The ADRB2 gene, which encodes the beta 2-adrenergic receptor, is one of the most extensively studied genes with respect to asthma prevalence and severity. The Arg16Gly (+46A > G) and Gln27Glu (+79C > G) polymorphisms in the ADRB2 gene cause changes in the amino acids flanking the receptor ligand site, altering the response to bronchodilators and the risk of asthma through complex pathways. The ADRB2 polymorphisms affect beta-adrenergic bronchodilator action and are a tool to identify at-risk populations. To determine the frequency of these two polymorphisms in allergic asthma patients and healthy subjects and to correlate these data with the occurrence and severity of asthma. Eighty-eight allergic asthma patients and 141 healthy subjects were included in this study. The ADRB2 polymorphisms were analyzed using the amplification-refractory mutation system - polymerase chain reaction (ARMS-PCR) technique. The statistical analysis was performed with the SPSS 21.0 software using the Fisher's Exact and χ2 tests. The ADRB2 polymorphisms were associated with asthma occurrence. The Arg16Arg, Gln27Gln and Gln27Glu genotypes were risk factors; the odds ratios were 6.782 (CI = 3.07 to 16.03), 2.120 (CI = 1.22 to 3.71) and 8.096 (CI = 3.90 to 17.77), respectively. For the Gly16Gly and Glu27Glu genotypes, the odds ratios were 0.312 (CI = 0.17 to 0.56) and 0.084 (CI = 0.04 to 0.17), respectively. The haplotype analysis showed that there were associations between the following groups: Arg16Arg-Gln27Gln (OR = 5.108, CI = 1.82 to 16.37), Gly16Gly-Glu27Glu (OR = 2.816, CI = 1.25 to 6.54), Arg16Gly-Gln27Glu (OR = 0.048, CI = 0.01 to 0.14) and Gly16Gly-Gln27Glu (OR = 0.1036, CI = 0.02 to 0.39). The polymorphism Gln27Glu was associated with asthma severity, as the Gln27Gln genotype was a risk factor for severe asthma (OR = 2.798, CI = 1.099 to 6.674) and the Gln27Glu genotype was a protective factor for mild (OR = 3.063, CI = 1.037 to 9.041) and severe (OR = 0.182, CI = 0.048 to 0.691) asthma. The Arg16Gly and Gln27Glu polymorphisms in the ADRB2 gene are associated with asthma presence and severity.10

Association of the polymorphisms Gln27, Glu27, Arg16 e Gly16 from ADRB2R gene with asthma

Orientador: Carmen Silvia BertuzzoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias MedicasResumo: A asma atópica é uma doença com prevalência média na população brasileira de 20%. Estima-se que 60% dos casos de asma sejam intermitentes ou persistentes leves, 25% a 30% moderados e 5% a 10% graves. O receptor beta-2-adrenérgico, quando ativado, provoca o relaxamento da musculatura lisa das vias aéreas. Os polimorfismos Arg -> Gly 16 (46 A->G) e Gln -> Glu27 (79C->G) do gene ADRB2 provocam uma mudança nos aminoácidos situados ao lado do sítio ligante do receptor. Estes receptores não são responsáveis pela presença da asma, mas agem como moduladores de gravidade da doença. Desse modo, o estudo dos polimorfismos do gene ADRB2 é muito importante para prever a resposta ao uso de broncodilatadores beta-adrenérgicos no tratamento da asma atópica. Os objetivos do trabalho foram: 1) Determinar o genótipo de pacientes asmáticos e voluntários sadios quanto aos polimorfismos Gln27, Glu27, Arg16 e Gly16. 2) Verificar se existe correlação entre o genótipo estudado e a gravidade da asma. Foram genotipados 87 pacientes com asma atópica, de acordo com o critério GINA, e 141 voluntários sadios. Após a extração de DNA do sangue periférico foi efetuada PCR-alelo específica (ARMS). No método de ARMS-PCR é utilizado um primer comum a todas as reações e outro alelo específico,isto é, apenas uma base nitrogenada é diferente. Além disso é utilizado um par de primers como controle interno da reação. Os resultados encontrados foram analisados através do teste de qui-quadrado. Amostra de pacientes quanto ao códon 16 não está em equilíbrio de Hardy-Weinberg, entretanto a amostra controle está. No códon 27, ambas as amostras estão em desequilíbrio. A diferença na freqüência dos alelos no códon 16 entre os pacientes e o grupo controle foi significativa, enquanto no códon 27 não. Na comparação entre os diferentes genótipos no códon 16 dos asmáticos e do grupo controle foi observada diferença significativa, modtrando que o alelo Arg 16 pode estar envolvido na etiologia da asma. Comparando-se os pacientes com asma grave e grupo controle, foi encontrada uma diferença significativa, assim como quando comparados os pacientes com moderada, também sendo encontrada diferença significativa quando comparados os pacientes leve. No códon 27 verificou-se diferença significativa entre os genótipos dos pacientes e voluntários sadios. Comparando-se os pacientes com asma grave e grupo controle foi encontrado uma diferença significativa, assim como quando comparados os pacientes com moderada, também sendo encontrada diferença significativa quando comparados os pacientes leve. Na verificação dos genótipos do grupo controle e do total de pacientes temos uma diferença significativa. Na comparação entre os grupos de asmáticos só tivemos diferença significativa entre o grupo de asma grave e leve. Na comparação de asma grave e moderada não tivemos diferença significativa assim como moderada e leve. Os genótipo homozigotos Arg 16 parece estar relacionada à presença da asma e homozigotos Gln 27 parecem estar associados com a gravidade da asmaAbstract: The atopic asthma is an illness with 20% of average prevalence in the Brazilian population. It?s estimated that 60% of the asthma cases are intermittent or persistent light, 25% to 30% moderate and 5% to 10% serious. The receptor beta-2-adrenergic, when activated, causes the relaxation of the aerial ways' smooth muscle. The polymorphisms Arg -> Gly 16 (46 A->G) and Gln -> Glu27 (79C->G) from the ADRB2 gene cause a change on amino acids situated beside the receptor?s linking place. These receptors are not responsible for the asthma?s occurrence, but they act as modulators of the illness? severity. In this way, the study of the ADRB2 gene's polymorphisms is very important to foresee the reply of using beta-adrenergic bronchodilators in the treatment of the atopic asthma. The objectives of the proceeding were: 1) Determinate the genotype of healthy and asthmatic voluntary patients in respect of the polymorphisms Gln27, Glu27, Arg16 and Gly16. 2) Verify if there is a correlation between the studied genotype and asthma?s severity. 87 patients with atopic asthma were genotyped, in accordance with the healthy criterion GINA, and 141 volunteers. After the extraction of peripheral blood's DNA, an specific PCR-allele (ARMS) was made. In the ARMS-PCR method, it is used a common primer for all the reactions and another specific allele, that means, only one base is different. Moreover, a pair of primers is used as internal control of the reaction. The achieved results were analyzed through the qui-square test. The patients' sample, according to codon 16, is not in Hardy-Weinberg equilibrium, while the control sample is. In codon 27, both of the samples are in disequilibrium. The difference in the frequency of alleles in codon 16 between the patients and the control group was significant, while in codon 27 not. In the comparison between the different genotypes in codon 16 of the asthmatic and the control group, significant difference was observed, showing that the Arg 16 allele can be involved in the asthma's etiology. Comparing the patients with serious asthma and the control group, significant difference was found, as well as when compared the patients with moderate, also being found significant difference when compared the patients with light. In codon 27, significant difference was verified between the genotypes of patients and healthy volunteers. Verifying the genotypes of the control group and the total of patients, we have a significant difference. In the comparison between the asthmatic groups, we only had significant difference between the serious asthma group and the light one. In the comparison between serious and moderate asthma, we didn?t have significant difference, as well as between moderate and light. The genotype homozygote Arg 16 seems to be related to the asthma's occurrence and homozygote Gln 27 seems to be associated with the asthma?s severityMestradoMestre em Farmacologi