ASSOCIATION ANALYSIS OF THE DOPAMINE-D4 GENE EXON-III VNTR AND HEROINABUSE IN CHINESE SUBJECTS

Although social and cultural influences are clearly important, family, twin and adoption studies indicate that genes contribute significantl y to substance abuse.(1-3) Substance abuse is associated with novelty seeking, a heritable human personality trait which may be influenced b y alleles of the dopamine D4 (DRD4) gene exon III VNTR.(4,5) Consequen tly Kotler et al(6) analysed the DRD4 VNTR in opiate-dependent subject s from Israel, and found a significant excess of the 7-repeat allele, We have attempted to replicate this finding using a Han Chinese case-c ontrol sample of 121 heroin-dependent subjects and 154 normal controls . We found two 7-repeat alleles which occurred exclusively in the pati ent group, and overall there was an excess of longer alleles, which di d not reach significance (chi(2) = 7.04; P = 0.07). When the D4 VNTR w as divided into 'long' (5-7 repeats) and 'short' (2-4 repeats), a sign ificant excess of long alleles was observed in the patient group (P = 0.023, one-tailed), with an odds ratio of 2.30 (95% CI 1.07-4.93). We conclude that our findings support the hypothesis that alleles of the DRD4 exon III VNTR are susceptibility factors for heroin abuse.