CHRNA5/CHRNA3 polymorphisms and tobacco smoking risk in a Brazilian population sample

Tobacco smoking is a major risk factor of several diseases such as lung cancer, stroke, chronic obstructive pulmonary disease and increases the susceptibility to infectious diseases. The understanding of smoking addiction requires phenotyping and genotyping studies. Variations in CHRNA5/CHRNA3 can alter receptor responses to nicotine and thus interfere with smoking behavior and risk. Therefore, this study aimed to investigate the association of CHRNA5 rs16969968 and CHRNA3 rs578776 with smoking behavior in a Brazilian population sample, comprising 449 subjects. Smoking data was obtained from a questionnaire. The polymorphisms were genotyped by Polymerase Chain Reaction (PCR). Associations were verified using logistic and linear regression analyses. We found that women with the variant AA genotype for CHRNA5 rs16969968 were at significantly increased risk of smoking, with an OR of 3.09 (95% CI: 1.09-8.76; p= 0.033). The variant TT genotype of CHRNA3 rs578776 showed protection against smoking and later smoking initiation in the overall population and in women, with an OR of 0.41 (95% CI: 0.19-0.88; p=0.022). In conclusion, CHRNA5 rs16969968 and CHRNA3 rs578776 were associated with increased risk and protective effect against smoking, respectively, in a Brazilian population sample. Gender and recessive homozygosis of the polymorphisms variants resulted in a significant effect regarding the results.