Association of the DRD2 gene Taq1A polymorphism and smoking behavior: a meta-analysis and new data.
BACKGROUND
Many studies have investigated the association of the dopamine type-2 receptor (DRD2) Taq1A polymorphism with tobacco use and cigarette smoking behaviors, but findings remain equivocal. There is a biological basis for considering that this association differs by sex, and differences in subpopulations might explain some of the contradictory evidence.


METHODS
Our a priori hypothesis was that the association of the DRD2 Taq1A polymorphism with smoking behavior would be more prominent in females than males. We therefore investigated the strength of evidence for an association between the DRD2 Taq1A polymorphism and smoking behavior in a large sample of females and used meta-analytic techniques to synthesize existing published data and explore the role of sex in explaining any heterogeneity between studies.


RESULTS
We did not observe any strong evidence of association between the DRD2 Taq1A polymorphism and smoking behavior, including smoking initiation, smoking persistence, and smoking rate, either in our female sample or in our meta-analysis of 29 studies, comprising 28 published studies and the data from the present study. Metaregression suggested an association between the proportion of male participants in a study and the individual study effect size, indicating a larger effect size with a greater proportion of male participants for smoking initiation and smoking persistence. This effect did not appear to be due to the inclusion of the data from the present study.


CONCLUSIONS
Available evidence does not support an association between the DRD2 Taq1A polymorphism and smoking behavior. Contrary to our a priori hypothesis, we found evidence of a stronger association in males than in females.
Munafò
Marcus R
MR
Department of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK. marcus.munafo@bristol.ac.uk
Timpson
Nicholas J
NJ
David
Sean P
SP
Ebrahim
Shah
S
Lawlor
Debbie A
DA
D000483:Alleles; D016739:Behavior, Addictive / Q000235:genetics*; D019317:Evidence-Based Medicine; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D020641:Polymorphism, Single Nucleotide; D016032:Randomized Controlled Trials as Topic; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D012737:Sex Factors; D012907:Smoking / Q000235:genetics*
D017448:Receptors, Dopamine D2