Duaux et al. [67] studied the BalI polymorphism in the DRD3 gene using a French Caucasian male population, where 54 opioid dependent patients and 70 control subjects were investigated [67]. While there were no significant genotype differences between the groups, patients had a higher sensation-seeking score on the Zuckerman scale (26 ± 5) than controls (17 ± 6), (P=0.001) [67]. In addition, patients with a sensation-seeking score above 24 were more likely to be homozygous for either BalI allele than patients with a score below 24 (χ2 = 6.53, d.f. = 1, P = 0.038) or controls (χ2 = 4.48, d.f. = 1, P = 0.034) [67]. Sensation-seeking is considered a vulnerability factor for developing drug abuse behaviour, but the results are inconclusive and should be confirmed in larger samples.
