In contrast to the study published by Chen and colleagues (17), we did not observe any long lasting association between CHRNA5-A3-B4 gene variants and smoking abstinence rates in participants who received the placebo treatment. This discrepancy was unlikely to be the results of limited power since the current present investigation had a much bigger placebo group compared to the study by Chen and colleagues (566 in our combined studies versus 132 in the Chen et al., study (17)). It is possible the effects of the ‘tag’ SNPs are different among different ethnic groups due to the distinct haplotype structures.
