Efeitos do polimorfismo MAOA-uVNTR nos escores de QI de adultos com Transtorno de Deficit de Atenção/Hiperatividade (TDAH)
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2017-06
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Contini, Verônica
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Introdução: O transtorno de deficit de atenção e hiperatividade (TDAH) é uma desordem comportamental comum em crianças e que pode persistir na idade adulta. Ele caracteriza-se por sintomas persistentes de desatenção, hiperatividade e impulsividade. Embora as estimativas de prevalência relatadas em estudos variam, a prevalência de TDAH em crianças e adolescentes oscila de 5,9-7,1%, e resultados semelhantes são encontrados para adultos: 2,5-5,0%. Além disso, uma proporção significativa dos pacientes com TDAH também apresenta outras comorbidades associadas. Diversos estudos moleculares têm sido realizados na busca pelos genes envolvidos com o TDAH e, alguns deles, sugerem o envolvimento de variações no gene codificador da enzima monoamino oxidase A (MAOA), a qual desempenha um papel importante na regulação de componentes dos sistemas dopaminérgico e serotoninérgico. Estudos moleculares sugerem que o gene possui um papel importante em características relacionadas à impulsividade, agressividade e comportamentos aditivos. Objetivo: O objetivo principal deste estudo é avaliar a associação entre o polimorfismo MAOA-uVNTR, localizado na região promotora do gene MAOA, e o TDAH em adultos. Metodologia: As amostras foram compostas por 562 indivíduos com TDAH, diagnosticados de acordo com os critérios do DSM-4, e 638 indivíduos controles, de ambos os sexos. O polimorfismo MAOA-uVNTR foi amplificado pela técnica de reação em cadeia da polimerase (PCR) e genotipado por eletroforese em gel de poliacrilamida 6%. Resultados: Não foi detectada uma associação significativa entre o polimorfismo investigado e o TDAH. Observou-se, no entanto, um efeito do polimorfismo nos escores de quociente de inteligência (QI) estimado em homens com TDAH. Portadores do alelo de baixa atividade do polimorfismo (3 repetições) apresentaram escores de QI verbal (p= <0,0001) e QI total (p= 0,001) significativamente mais baixos, quando comparados aos indivíduos portadores dos alelos de alta atividade (3.5 e 4 repetições). Conclusão: Nossos resultados indicam que o polimorfismo MAOA-uVNTR não está associado diretamente ao TDAH. No entanto, sugerem que o mesmo possa estar envolvido com a variabilidade observada nos escores de QI de pacientes com TDAH, mais especificamente em indivíduos do sexo masculino.
Introduction: Attention deficit hyperactivity disorder (ADHD) is a common behavioral disorder in children that can persist into adulthood. ADHD is characterized by persistent symptoms of inattention and hyperactivity/impulsivity. Although the estimates of prevalence vary in some studies, the prevalence of this disorder in children and adolescents ranges from 5.9-7.1%, and similar results are found for adults: 2.5-5.0%. In addition, a significant proportion of ADHD patients present other comorbidities. Several molecular studies have been employed in the search for the genes involved in ADHD susceptibility and some of them suggest the involvement of the gene that codes for the monoamine oxidase A enzyme (MAOA), which plays an important role in the regulation of components of the dopaminergic and serotoninergic systems. Molecular studies have suggest an important for the MAOA gene in characteristics related to impulsivity, aggressiveness and additive behaviors. Objective: The main objective of this study is to evaluate the association between the MAOA-uVNTR polymorphism, located in the promoter region of the MAOA gene, and ADHD in adults. Methods: The samples were composed by 535 individuals with ADHD, diagnosed according to DSM-IV criteria, and 639 control subjects, of both genders. The MAOA-uVNTR polymorphism was amplified by the polymerase chain reaction (PCR) and genotyped by 6% polyacrylamide gel electrophoresis. Results: There was no significant association between the investigated polymorphism and ADHD. However, it was observed an effect of the polymorphism on estimated intelligence quotient (IQ) scores in men with ADHD. Carriers of the low activity allele (3 repeats) presented significantly lower verbal IQ (p < 0.001) and total IQ scores (p = 0.001) when compared to individuals with high activity alleles (3.5 and 4 repeats). Conclusion: Our results indicate that the MAOA-uVNTR polymorphism is not directly associated with ADHD. However, they suggest that MAOA may be involved in the observed variability of IQ scores of patients with ADHD, more specifically in males.
Introduction: Attention deficit hyperactivity disorder (ADHD) is a common behavioral disorder in children that can persist into adulthood. ADHD is characterized by persistent symptoms of inattention and hyperactivity/impulsivity. Although the estimates of prevalence vary in some studies, the prevalence of this disorder in children and adolescents ranges from 5.9-7.1%, and similar results are found for adults: 2.5-5.0%. In addition, a significant proportion of ADHD patients present other comorbidities. Several molecular studies have been employed in the search for the genes involved in ADHD susceptibility and some of them suggest the involvement of the gene that codes for the monoamine oxidase A enzyme (MAOA), which plays an important role in the regulation of components of the dopaminergic and serotoninergic systems. Molecular studies have suggest an important for the MAOA gene in characteristics related to impulsivity, aggressiveness and additive behaviors. Objective: The main objective of this study is to evaluate the association between the MAOA-uVNTR polymorphism, located in the promoter region of the MAOA gene, and ADHD in adults. Methods: The samples were composed by 535 individuals with ADHD, diagnosed according to DSM-IV criteria, and 639 control subjects, of both genders. The MAOA-uVNTR polymorphism was amplified by the polymerase chain reaction (PCR) and genotyped by 6% polyacrylamide gel electrophoresis. Results: There was no significant association between the investigated polymorphism and ADHD. However, it was observed an effect of the polymorphism on estimated intelligence quotient (IQ) scores in men with ADHD. Carriers of the low activity allele (3 repeats) presented significantly lower verbal IQ (p < 0.001) and total IQ scores (p = 0.001) when compared to individuals with high activity alleles (3.5 and 4 repeats). Conclusion: Our results indicate that the MAOA-uVNTR polymorphism is not directly associated with ADHD. However, they suggest that MAOA may be involved in the observed variability of IQ scores of patients with ADHD, more specifically in males.
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QI estimado; MAOA; TDAH; Adultos
Citação
CONSTANTIN, Pâmela Camini. Efeitos do polimorfismo MAOA-uVNTR nos escores de QI de adultos com Transtorno de Deficit de Atenção/Hiperatividade (TDAH). 2016. Dissertação (Mestrado) – Curso de Biotecnologia, Universidade do Vale do Taquari - Univates, Lajeado, 19 dez. 2016. Disponível em: http://hdl.handle.net/10737/1585.