Epidemiologia genética do acidente vascular cerebral: identificação dos genes envolvidos na susceptibilidade e na recuperação do doente

Tese de mestrado. Biologia (Biologia Humana e Ambiente). Universidade de Lisboa, Faculdade de Ciências, 2012O Acidente Vascular Cerebral (AVC) é um evento neurológico agudo resultante de uma doença cardiovascular, no qual a afluência de sangue ao cérebro se vê comprometida, seja por um bloqueio ou por uma ruptura num vaso sanguíneo cerebral. Esta doença representa uma das principais causas de morte e morbilidade em todo o mundo, pelo que o estudo das componentes ambientais e genéticas nela envolvidas se torna fundamental para a implementação de planos de prevenção que visem minimizar as suas consequências. Com vista a contribuir para o desenvolvimento do estudo das variantes genéticas implicadas quer na susceptibilidade, quer na recuperação após um AVC, os objectivos deste estudo foram os de, por um lado, estudar a relevância do Single Nucleotide Polymorphism (SNP) rs1229984 do gene ADH1B sobre o risco de AVC e, por outro, identificar novos polimorfismos envolvidos no processo de recuperação. Recorrendo a um TaqMan® Drug Metabolism Genotyping Assay foi feita uma análise comparativa de dois grupos de indivíduos, um grupo saudável (controlos) e outro de doentes que sofreram AVC (casos) e verificou-se que o SNP rs1229984 do gene ADH1B, implicado no metabolismo do álcool, está, de facto, envolvido na susceptibilidade ao AVC. Porém, a mediação desta relação pelo consumo de álcool não se verificou, pelo que se sugere a replicação do estudo. Tendo por base um rastreio genómico previamente efectuado através de um Genome Wide Association Study (GWAS) em pooled samples, cujo objectivo era a identificação de genes envolvidos na recuperação após um AVC, realizou-se um novo estudo acerca da recuperação após um AVC, como mesmo objectivo. Seleccionaram-se diversos SNPs segundo critérios bem definidos (e distintos do primeiro estudo), para genotipagem individual, através de ferramentas como Sequenom iPLEX e TaqMan® Pre-Designed SNP Genotyping Assays e Restriction Fragment Lenght Polymorphism (RFLP), em grupos de indivíduos com recuperação desigual três meses após um AVC. Este estudo permitiu identificar um novo gene candidato envolvido na recuperação, o CDKAL1 e confirmar o potencial envolvimento do gene BBS9 no mesmo processo, o qual já tinha sido identificado anteriormente como gene associado à recuperação. Foi também possível aferir alguns aspectos relacionados com a interpretação dos resultados de um GWAS em pooled samples, nomeadamente acerca da importância das réplicas da formação dos pools e das réplicas de alelotipagem e acerca da necessidade de validação dos resultados por genotipagem individual. Tendo em conta a identificação de genes candidatos para a recuperação após um AVC, sugere-se que sejam desenvolvidos trabalhos futuros, nomeadamente estudos funcionais, no sentido de compreender as vias através das quais os referidos genes actuarão sobre o processo de recuperação após um AVC. Estudos de replicação em outras populações são também aconselhados, para validação das conclusões tiradas neste estudo.Stroke is an acute neurological event resulting from a cardiovascular disease in which the blood supply to the brain gets compromised either by a blockage or a rupture in a cerebral blood vessel. This disease is a significant cause of death and disability worldwide, thus the study of genetic and environmental variants involved in stroke susceptibility and outcome becomes essential to allow the implementation of effective prevention plans aiming to minimize its consequences. To contribute to the study of genetic variants involved in stroke susceptibility or stroke recovery, the main objectives of this study were to determine the relevance of the ADH1B gene in stroke risk and to identify new genetic variants involved in stroke recovery. Using a TaqMan® Drug Metabolism Genotyping Assay we compared genotypes at the rs1229984 within ADH1B gene in a group of healthy individuals with a group of stroke patients and found that ADH1B gene, which is involved in alcohol metabolism, is associated with stroke susceptibility. We progressed with the analysis of a previous Genome Wide Association Study (GWAS) for stroke recovery in pooled samples. Several most relevant Single Nucleotide Polymorphisms (SNPs) were selected according to well defined criteria and were individually genotyped in groups of individuals with good and poor outcome at three months evaluation. Genotyping was performed using Sequenom iPLEX, TaqMan® Pre- Designed SNP Genotyping Assays and Restriction Fragment Lenght Polymorphism (RFLP). This study allowed the identification of a new candidate gene involved in stroke recovery, CDKAL1, and also allowed to confirm the involvement of a previously identified candidate gene BBS9 in the same process. It was also possible to assess some aspects related to the interpretation of the results of a GWAS in pooled samples that are important for the wider use of this technology in genomic studies. Given the identification of candidate genes, we suggest the development of future studies, including functional studies in order to understand which pathways of recovery the candidate genes affect. Replication in other populations is also suggested as a mean of validating the conclusions drawn in this study

Association between alcohol and cardiovascular disease: Mendelian randomisation analysis based on individual participant data.

OBJECTIVE: To use the rs1229984 variant in the alcohol dehydrogenase 1B gene (ADH1B) as an instrument to investigate the causal role of alcohol in cardiovascular disease. DESIGN: Mendelian randomisation meta-analysis of 56 epidemiological studies. PARTICIPANTS: 261 991 individuals of European descent, including 20 259 coronary heart disease cases and 10 164 stroke events. Data were available on ADH1B rs1229984 variant, alcohol phenotypes, and cardiovascular biomarkers. MAIN OUTCOME MEASURES: Odds ratio for coronary heart disease and stroke associated with the ADH1B variant in all individuals and by categories of alcohol consumption. RESULTS: Carriers of the A-allele of ADH1B rs1229984 consumed 17.2% fewer units of alcohol per week (95% confidence interval 15.6% to 18.9%), had a lower prevalence of binge drinking (odds ratio 0.78 (95% CI 0.73 to 0.84)), and had higher abstention (odds ratio 1.27 (1.21 to 1.34)) than non-carriers. Rs1229984 A-allele carriers had lower systolic blood pressure (-0.88 (-1.19 to -0.56) mm Hg), interleukin-6 levels (-5.2% (-7.8 to -2.4%)), waist circumference (-0.3 (-0.6 to -0.1) cm), and body mass index (-0.17 (-0.24 to -0.10) kg/m(2)). Rs1229984 A-allele carriers had lower odds of coronary heart disease (odds ratio 0.90 (0.84 to 0.96)). The protective association of the ADH1B rs1229984 A-allele variant remained the same across all categories of alcohol consumption (P=0.83 for heterogeneity). Although no association of rs1229984 was identified with the combined subtypes of stroke, carriers of the A-allele had lower odds of ischaemic stroke (odds ratio 0.83 (0.72 to 0.95)). CONCLUSIONS: Individuals with a genetic variant associated with non-drinking and lower alcohol consumption had a more favourable cardiovascular profile and a reduced risk of coronary heart disease than those without the genetic variant. This suggests that reduction of alcohol consumption, even for light to moderate drinkers, is beneficial for cardiovascular health

Association between alcohol and cardiovascular disease: Mendelian randomisation analysis based on individual participant data.

OBJECTIVE: To use the rs1229984 variant in the alcohol dehydrogenase 1B gene (ADH1B) as an instrument to investigate the causal role of alcohol in cardiovascular disease. DESIGN: Mendelian randomisation meta-analysis of 56 epidemiological studies. PARTICIPANTS: 261 991 individuals of European descent, including 20 259 coronary heart disease cases and 10 164 stroke events. Data were available on ADH1B rs1229984 variant, alcohol phenotypes, and cardiovascular biomarkers. MAIN OUTCOME MEASURES: Odds ratio for coronary heart disease and stroke associated with the ADH1B variant in all individuals and by categories of alcohol consumption. RESULTS: Carriers of the A-allele of ADH1B rs1229984 consumed 17.2% fewer units of alcohol per week (95% confidence interval 15.6% to 18.9%), had a lower prevalence of binge drinking (odds ratio 0.78 (95% CI 0.73 to 0.84)), and had higher abstention (odds ratio 1.27 (1.21 to 1.34)) than non-carriers. Rs1229984 A-allele carriers had lower systolic blood pressure (-0.88 (-1.19 to -0.56) mm Hg), interleukin-6 levels (-5.2% (-7.8 to -2.4%)), waist circumference (-0.3 (-0.6 to -0.1) cm), and body mass index (-0.17 (-0.24 to -0.10) kg/m(2)). Rs1229984 A-allele carriers had lower odds of coronary heart disease (odds ratio 0.90 (0.84 to 0.96)). The protective association of the ADH1B rs1229984 A-allele variant remained the same across all categories of alcohol consumption (P=0.83 for heterogeneity). Although no association of rs1229984 was identified with the combined subtypes of stroke, carriers of the A-allele had lower odds of ischaemic stroke (odds ratio 0.83 (0.72 to 0.95)). CONCLUSIONS: Individuals with a genetic variant associated with non-drinking and lower alcohol consumption had a more favourable cardiovascular profile and a reduced risk of coronary heart disease than those without the genetic variant. This suggests that reduction of alcohol consumption, even for light to moderate drinkers, is beneficial for cardiovascular health

Association between alcohol and cardiovascular disease: Mendelian randomisation analysis based on individual participant data.

To use the rs1229984 variant in the alcohol dehydrogenase 1B gene (ADH1B) as an instrument to investigate the causal role of alcohol in cardiovascular disease.Mendelian randomisation meta-analysis of 56 epidemiological studies.261 991 individuals of European descent, including 20 259 coronary heart disease cases and 10 164 stroke events. Data were available on ADH1B rs1229984 variant, alcohol phenotypes, and cardiovascular biomarkers.Odds ratio for coronary heart disease and stroke associated with the ADH1B variant in all individuals and by categories of alcohol consumption.Carriers of the A-allele of ADH1B rs1229984 consumed 17.2% fewer units of alcohol per week (95% confidence interval 15.6% to 18.9%), had a lower prevalence of binge drinking (odds ratio 0.78 (95% CI 0.73 to 0.84)), and had higher abstention (odds ratio 1.27 (1.21 to 1.34)) than non-carriers. Rs1229984 A-allele carriers had lower systolic blood pressure (-0.88 (-1.19 to -0.56) mm Hg), interleukin-6 levels (-5.2% (-7.8 to -2.4%)), waist circumference (-0.3 (-0.6 to -0.1) cm), and body mass index (-0.17 (-0.24 to -0.10) kg/m(2)). Rs1229984 A-allele carriers had lower odds of coronary heart disease (odds ratio 0.90 (0.84 to 0.96)). The protective association of the ADH1B rs1229984 A-allele variant remained the same across all categories of alcohol consumption (P=0.83 for heterogeneity). Although no association of rs1229984 was identified with the combined subtypes of stroke, carriers of the A-allele had lower odds of ischaemic stroke (odds ratio 0.83 (0.72 to 0.95)).Individuals with a genetic variant associated with non-drinking and lower alcohol consumption had a more favourable cardiovascular profile and a reduced risk of coronary heart disease than those without the genetic variant. This suggests that reduction of alcohol consumption, even for light to moderate drinkers, is beneficial for cardiovascular health

Association between alcohol and cardiovascular disease : Mendelian randomisation analysis based on individual participant data

Objective: To use the rs1229984 variant in the alcohol dehydrogenase 1B gene (ADH1B) as an instrument to investigate the causal role of alcohol in cardiovascular disease. Design: Mendelian randomisation meta-analysis of 56 epidemiological studies. Participants: 261 991 individuals of European descent, including 20 259 coronary heart disease cases and 10 164 stroke events. Data were available on ADH1B rs1229984 variant, alcohol phenotypes, and cardiovascular biomarkers. Main outcome measures: Odds ratio for coronary heart disease and stroke associated with the ADH1B variant in all individuals and by categories of alcohol consumption. Results: Carriers of the A-allele of ADH1B rs1229984 consumed 17.2% fewer units of alcohol per week (95% confidence interval 15.6% to 18.9%), had a lower prevalence of binge drinking (odds ratio 0.78 (95% CI 0.73 to 0.84)), and had higher abstention (odds ratio 1.27 (1.21 to 1.34)) than non-carriers. Rs1229984 A-allele carriers had lower systolic blood pressure (-0.88 (-1.19 to -0.56) mm Hg), interleukin-6 levels (-5.2% (-7.8 to -2.4%)), waist circumference (-0.3 (-0.6 to -0.1) cm), and body mass index (-0.17 (-0.24 to -0.10) kg/m2). Rs1229984 A-allele carriers had lower odds of coronary heart disease (odds ratio 0.90 (0.84 to 0.96)). The protective association of the ADH1B rs1229984 A-allele variant remained the same across all categories of alcohol consumption (P=0.83 for heterogeneity). Although no association of rs1229984 was identified with the combined subtypes of stroke, carriers of the A-allele had lower odds of ischaemic stroke (odds ratio 0.83 (0.72 to 0.95)). Conclusions: Individuals with a genetic variant associated with non-drinking and lower alcohol consumption had a more favourable cardiovascular profile and a reduced risk of coronary heart disease than those without the genetic variant. This suggests that reduction of alcohol consumption, even for light to moderate drinkers, is beneficial for cardiovascular health