Study Of Dopamine D₄ Gene Polymorphism In Tourette Syndrome In Fujian Region

Objective To study the relationship between Tourette syndrome and the dopaminereceptor-4 gene exon3 48bp VNTR polymorphism in children from Fujian region.Methods The genotypes and alleles of 118 normal controls and 106 children withTS were detected by polymerase chain reaction, denaturing polyacry lamide gelelectrophorsis and silver staining. Some of them were directly sequenced to examinethe genotypes. The 48bp VNTR alleles and genotypes of patients with TS and controlswere compared by chi square test.Results 1.Eight genotypes were found in 224 individuals based on different 48bpVNTR alleles, which were 2/2,2/3,2/4,2/5,3/4,4/4,4/5,4/6.2.DRD4 genotypes distribution :The most common genotype was 4/4.There wasstatistically significant difference in genotype distribution between TS group andcontrol group(X~2 = 19.564, P<0.01).3.DRD4 alleles frequency distribution : five alleles were found, the repeat numbers of48bp were 2 to 6. The common unit was 4-repeat allele. There was statisticallysignificant difference in allele frequency distribution between TS group and normalcontrol group(X~2 = 16.168, P<0.01).4.Contrasting DRD4 48bp VNTR longer allele with shorter allele: When the DRD448bp VNTR was divided into " longer allele"(≥5 repeats) and "shorter allele"(<5repeats), statistically significant differences of both longer and shorter alleles werefound in both groups(X~2=4.0581, P<0.05).Conclusions In this study, we found eight genotypes and five alleles of DRD4 48bpVNTR.There were statistically significant differences in genotype distribution, allelefrequency, contrasting longer allele with shorter allele between TS group and controlgroup.Thus we concluded that DRD4 48bp VNTR polymorphism maybe beassociated with TS in Fujian region.