RESUMO
Previous studies have identified variants in genes encoding proteins associated with the degree of addiction, smoking onset, and cessation. We aimed to describe thirty-one single nucleotide polymorphisms (SNPs) in seven candidate genomic regions spanning six genes associated with tobacco-smoking in a cross-sectional study from two different interventions for quitting smoking: (1) thirty-eight smokers were recruited via multimedia to participate in e-Decídete! program (e-Dec) and (2) ninety-four attended an institutional smoking cessation program on-site. SNPs genotyping was done by real-time PCR using TaqMan probes. The analysis of alleles and genotypes was carried out using the EpiInfo v7. on-site subjects had more years smoking and tobacco index than e-Dec smokers (p < 0.05, both); in CYP2A6 we found differences in the rs28399433 (p < 0.01), the e-Dec group had a higher frequency of TT genotype (0.78 vs. 0.35), and TG genotype frequency was higher in the on-site group (0.63 vs. 0.18), same as GG genotype (0.03 vs. 0.02). Moreover, three SNPs in NRXN1, two in CHRNA3, and two in CHRNA5 had differences in genotype frequencies (p < 0.01). Cigarettes per day were different (p < 0.05) in the metabolizer classification by CYP2A6 alleles. In conclusion, subjects attending a mobile smoking cessation intervention smoked fewer cigarettes per day, by fewer years, and by fewer cumulative pack-years. There were differences in the genotype frequencies of SNPs in genes related to nicotine metabolism and nicotine dependence. Slow metabolizers smoked more cigarettes per day than intermediate and normal metabolizers.
Assuntos
Abandono do Hábito de Fumar , Tabagismo , Estudos Transversais , Citocromo P-450 CYP2A6/genética , Genótipo , Humanos , Polimorfismo de Nucleotídeo Único , Fumar/genética , Tabagismo/genéticaRESUMO
BACKGROUND: Susceptibility to Chronic Myeloid Leukemia (CML) may be modulated by genetic variables. However, the majority of previous investigations have focused on genetically homogeneous populations, resulting in a lack of evidence on how genetic factors may influence the development of CML in miscegenated populations. We analyzed 30 polymorphisms in genes related to DNA repair, folate metabolism, transmembrane transport, xenobiotic metabolism, and pyrimidine synthesis in relation to their potential role in the susceptibility of the individual to CML. METHODS: This case-control study included 126 healthy individuals and 143 patients diagnosed with CML from the admixed population of the Brazilian Amazon. The samples were genotyped by real-time PCR and the genetic ancestry analysis was based on a panel of 61 ancestry informative markers. RESULTS: The results indicated a protective effect against the development of CML in carriers of the C allele of the rs28399433 (CYP2A6) gene and the CC genotype of the rs3742106 (ABCC4) gene. CONCLUSION: Our findings suggest that the rs3742106 (ABCC4) and rs28399433 (CYP2A6) polymorphisms may modulate susceptibility to CML in a population of the Brazilian Amazon region.
Assuntos
Citocromo P-450 CYP2A6/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Proteínas Associadas à Resistência a Múltiplos Medicamentos/genética , Polimorfismo de Nucleotídeo Único , Adulto , Brasil , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
Nicotine is the major pharmacologically active substance in tobacco. Several studies have examined genotypes related to nicotine metabolism, but few studies have been performed in the Mexican population. The objective was to identify associations between gene variants in metabolizing enzymes and the urinary levels of nicotine metabolites among Mexican smokers. The levels of nicotine and its metabolites were determined in the urine of 88 young smokers from Mexico, and 167 variants in 24 genes associated with nicotine metabolism were genotyped by next-generation sequencing (NGS). Trans-3'-hydroxy-cotinine (3HC) and 4-hydroxy-4-(3-pyridyl)-butanoic acid were the most abundant metabolites (35 and 17%, respectively). CYP2A6*12 was associated with 3HC (p = 0.014). The rs145014075 was associated with creatinine-adjusted levels of nicotine (p = 0.035), while the rs12471326 (UGT1A9) was associated to cotinine-N-glucuronide (p = 0.030). CYP2A6 and UGT1A9 variants are associated to nicotine metabolism. 4HPBA metabolite was an abundant urinary metabolite in young Mexican smokers.
Assuntos
Citocromo P-450 CYP2A6/genética , Variação Genética/genética , Glucuronosiltransferase/genética , Nicotina/urina , Fumar/genética , Fumar/urina , Adolescente , Adulto , Feminino , Humanos , Masculino , México/epidemiologia , Polimorfismo Genético/genética , Fumantes , Fumar/epidemiologia , UDP-Glucuronosiltransferase 1A , Adulto JovemRESUMO
BACKGROUND: The identification of variants in genes involved in nicotine metabolism may have implications for the pharmacological therapy of smoking. In the scenario of precision medicine, the aim of this study was to evaluate a possible association of cytochrome P450 2A6 and 2B6 polymorphisms with varenicline pharmacotherapy. METHODS: The present study included 167 patients treated with varenicline in monotherapy who were from a cohort study of 1049 patients (treated with smoking cessation drugs: nicotine replacement therapy, bupropion, varenicline, or combinations of same). Smoking cessation success was considered for patients who completed 6 months of continuous abstinence. The CYP2A6 rs1801272 and rs28399433 and CYP2B6 rs8109525 polymorphisms were genotyped by real-time PCR using the TaqMan® platform. RESULTS: Patients with AG or GG genotypes for CYP2B6 rs8109525 had a higher success rate of smoking cessation with varenicline (51.2%) compared with carriers of the AA genotypes (33.3%, P = 0.03, n = 167). The AG or GG genotypes were also associated with a higher odds ratio of success, even in a multivariate analysis adjusting for potential confounders (OR = 2.01; 95%CI = 1.01 to 4.00; P = 0.047). CONCLUSION: CYP2B6 rs8109525 was associated with a higher success rate of smoking cessation with varenicline treatment. This finding may be useful in pharmacogenomic strategies for smoking cessation therapy.
Assuntos
Citocromo P-450 CYP2B6/genética , Agentes de Cessação do Hábito de Fumar/uso terapêutico , Abandono do Hábito de Fumar/estatística & dados numéricos , Fumar/tratamento farmacológico , Vareniclina/uso terapêutico , Adulto , Citocromo P-450 CYP2A6/genética , Feminino , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Polimorfismo Genético , Fumar/genética , Resultado do TratamentoRESUMO
Nicotine is the main component of cigarettes that causes addiction, which is considered a complex disease, and genetic factors have been proposed to be involved in the development of addiction. The CYP2A6 gene encodes the main enzyme responsible for nicotine metabolism. Depending on the study population, different genetic variants of CYP2A6 associated with cigarette smoking have been described. Therefore, we evaluated the possible association between SNPs in CYP2A6 with cigarette smoking and nicotine addiction-related variables in Mexican mestizo smokers. We performed a genetic association study comparing light smokers (LS, n=349), heavy smokers (HS, n=351) and never-smokers (NS, n=394). SNPs rs1137115, rs4105144, rs1801272 and rs28399433 were genotyped in the CYP2A6 gene. We found that the A allele of rs1137115 (OR=1.41) in exon 1 of CYP2A6 and the T allele of rs4105144 (OR=1.32) in the 5' UTR of the gene are associated with the risk of cigarette smoking (p<0.05); rs1137115 affects the level of alternative splicing, resulting in a CYP2A6 isoform with low enzymatic activity, whereas rs4105144 is likely to be in a binding site for the transcription factor for glucocorticoids receptor (GR) and regulates the expression of CYP2A6. In addition, having a greater number of risk alleles (rs1137115 (A), rs4105144 (T) and rs28399433 (G)) is associated with a younger age at onset. The present study shows that in Mexican mestizos, the analyzed SNPs confer greater risk in terms of consumption and age of onset.
Assuntos
Citocromo P-450 CYP2A6/genética , Estudos de Associação Genética , Polimorfismo Genético , Fumar/genética , Adulto , Fatores Etários , Idoso , Alelos , Estudos de Casos e Controles , Feminino , Frequência do Gene , Predisposição Genética para Doença , Genótipo , Haplótipos , Humanos , Masculino , México , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Tabagismo/genéticaRESUMO
Cytochrome P450 2A6 (CYP2A6) catalyzes nicotine metabolism and contributes to the metabolism of the tobacco-specific lung carcinogen, NNK. Genetic variation in CYP2A6 may affect smoking behavior and contribute to lung cancer risk. A nested case-control study of 325 lung cancer cases and 356 controls was conducted within a prospective cohort of 18,244 Chinese men in Shanghai, China. Quantified were 4 allelic variants of CYP2A6 [*1(+51A), *4, *7, and *9] and urinary total nicotine, total cotinine, total trans-3'-hydroxycotinine (3HC) and total NNAL (an NNK metabolite). Calculated were total nicotine equivalents (TNE), the sum of total nicotine, total cotinine and total 3HC and the total 3HC:total cotinine ratio as a measure of CYP2A6 activity. The nicotine metabolizer status (normal, intermediate, slow and poor) was determined by CYP2A6 genotypes. The smoking-adjusted odds ratios (95% confidence intervals) of lung cancer for the highest vs lowest quartile of total nicotine, total cotinine, total 3HC, TNE and total NNAL were 3.03 (1.80-5.10), 4.70 (2.61-8.46), 4.26 (2.37-7.68), 4.71 (2.61-8.52), and 3.15 (1.86-5.33) (all Ptrend < 0.001), respectively. Among controls CYP2A6 poor metabolizers had a 78% lower total 3HC:total cotinine ratio and 72% higher total nicotine (Ptrend ≤ 0.002). Poor metabolizers had an odds ratio of 0.64 (95% confidence interval = 0.43-0.97) for lung cancer, which was statistically nonsignificant (odds ratio = 0.74, 95% confidence interval = 0.48-1.15) after adjustment for urinary TNE and smoking intensity and duration. The lower lung cancer risk observed in CYP2A6 poor metabolizers is partially explained by the strong influence of CYP2A6 genetic polymorphisms on nicotine uptake and metabolism.
Assuntos
Povo Asiático/genética , Citocromo P-450 CYP2A6/genética , Neoplasias Pulmonares/etiologia , Neoplasias Pulmonares/genética , Nicotina/metabolismo , Fumar/efeitos adversos , Biomarcadores Tumorais/análise , Estudos de Casos e Controles , China , Estudos de Coortes , Cotinina/metabolismo , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Nicotina/genética , Razão de Chances , Reação em Cadeia da Polimerase , Polimorfismo de Nucleotídeo Único , Fatores de Risco , Fumar/genéticaRESUMO
The higher proportion of smokers among Black people in Brazil has been attributed to socioeconomic disparities, but genetic factors could also contribute for this finding. This study aimed at investigating associations between smoking status with genetically defined ethnic ancestry and socioeconomic features in Brazilians. Blood samples were collected from 448 volunteers (66.7% male; age: 37.1 ± 11.4 years) classified as current smokers (CS: 60.9%), former smokers (FS: 8.9%) and never smokers (NS: 30.1%). Individual interethnic admixtures were determined using a 48 insertion-deletion polymorphisms ancestry-informative-marker panel. CS showed a lower amount of European ancestry than NS (0.837 ± 0.243 X 0.883 ± 0.194, p ≤ 0.05) and FS (0.837 ± 0.243 X 0.864 ± 0.230, p ≤ 0.05), and a higher proportion of African Sub-Saharan ancestry than FS (0.128 ± 0.222 X 0.07 ± 0.174, p ≤ 0.05) and NS (0.128 ± 0.222 X 0.085 ± 0.178, p ≤ 0.05). NS reported a higher number of years in school than CS (11.2 ± 3.7 X 8.9 ± 3.8, p ≤ 0.001). CS were less common in economic Class A (30%) and more common in Class B (56.8%). In multivariate analysis, only lower number of school years and lower economic class were associated with higher chances for CS. The use of genetic molecular markers for characterizing ethnic background confirmed that socioeconomic disparities are the main determinants of higher smoking rates among Blacks in Brazil.
Assuntos
Citocromo P-450 CYP2A6/genética , Polimorfismo Genético/genética , Fumar/etnologia , Adulto , Indígena Americano ou Nativo do Alasca , População Negra , Brasil/etnologia , Feminino , Marcadores Genéticos/genética , Humanos , Masculino , Fatores de Risco , Fumar/genética , Fatores Socioeconômicos , População BrancaRESUMO
BACKGROUND: Several studies have reported that variants rs16969968 G>A of the CHRNA5 gene and CYP2A6*12 of the CYP2A6 gene are associated with smoking and smoking refusal, respectively. In addition, some studies report that a higher cigarette consumption is associated with low body mass index (BMI). AIM: To analyze the allele and genotypic frequencies of these variants and their impact on smoking and BMI. MATERIAL AND METHODS: A blood sample was obtained and a survey about smoking habits was answered by 319 university students aged 18 to 35 years (127 women, 171 smokers), living in Northeastern Mexico. Genetic variants were studied by polymerase chain reaction/restriction fragment length polymorphism and their frequencies were associated with smoking and BMI. RESULTS: No associations were found between the analyzed variants and smoking in the study groups. However, there was an association among non-smoking subjects between the A allele of rs16969968 and high a BMI (p < 0.01). CONCLUSIONS: This last variant may be involved in food-addiction disorders.
Assuntos
Índice de Massa Corporal , Citocromo P-450 CYP2A6/genética , Frequência do Gene , Proteínas do Tecido Nervoso/genética , Receptores Nicotínicos/genética , Fumar/genética , Adolescente , Adulto , Estudos Transversais , Feminino , Variação Genética/genética , Genótipo , Humanos , Masculino , México , Nicotina/metabolismo , Reação em Cadeia da Polimerase/métodos , Polimorfismo Genético/genética , Adulto JovemRESUMO
OBJECTIVES: Efavirenz is widely prescribed for HIV-1 infection. Three polymorphisms in CYP2B6 define plasma efavirenz trough concentration strata that vary across an â¼10-fold range. We characterized associations between human genetic polymorphisms and virologic response among participants who received efavirenz-containing regimens in a prospective clinical trial. METHODS: We genotyped 76 polymorphisms in CYP2B6 (including those that define efavirenz concentration strata), CYP2A6, CYP3A4, CYP3A5 and ABCB1 and week 48 virologic responses in 360 Haitians who initiated efavirenz-containing regimens in protocol HT 001. Associations were characterized by logistic regression analysis and Fisher's exact test. RESULTS: Proportions with HIV-1 RNA <50 or <200 copies/mL did not differ across 10 CYP2B6 metabolizer strata. In analyses that combined strata into three metabolizer levels (extensive, intermediate and slow), the respective proportions were 0.79, 0.79 and 0.81 (<50 copies/mL cut-off) and 0.84, 0.86 and 0.87 (<200 copies/mL cut-off). Genetic associations were not identified after controlling for baseline variables or with other polymorphisms after adjusting for multiple comparisons. CONCLUSIONS: Virologic failures in HT 001 were not explained by genetic polymorphisms known to define the lowest plasma efavirenz concentration stratum.