多巴胺D4受体第3外显子48 bp可变重复序列多态性与抽动障碍的传递不平衡检测

目的研究多巴胺D4受体第3外显子48 bp可变重复序列(DRD4 exonⅢ48bpVNTR)多态性是否与抽动障碍(tic disorder, Tic)存在关联.方法采用国际标准化的收集病史,运用核心家系传递不平衡分析方法(transmission disequilibrium test, TDT)对122个核心家系进行关联分析,根据是否合并注意缺陷多动障碍(attention deficit and hyperactivity disorder, ADHD),将122个核心家系分为合并ADHD的抽动障碍组[合并ADHD的Tourette综合征(Tourette syndrome, TS)和慢性抽动障碍(chronic tic, CT),共40例,TS&ADHD]和抽动障碍组[TS和CT,共82例,TS&CT]两组,采用聚合酶链反应、可变重复序列多态性分析等技术,进行抽动障碍与DRD4 exonⅢ48 bpVNTR多态性的TDT分析.结果在这一多态性位点存在5个等位基因,分别为DRD4 exonⅢ48 bp的2～6个重复等位基因.总体上没有发现抽动障碍与DRD4 exonⅢ48 bpVNTR多态性存在传递不平衡(χ2＝7.44,P＝0.12),进一步对不伴ADHD的抽动障碍组进行的TDT分析也没有发现存在这一位点的传递不平衡(χ2＝3.38,P＝0.50);而在合并ADHD的抽动障碍组中发现,合并ADHD的抽动障碍与DRD4 exonⅢ48 bpVNTR多态性在总体上存在传递不平衡(χ2＝11.74,P＝0.02),进一步对单个等位基因的TDT分析显示,合并ADHD的抽动障碍与DRD4 exonⅢ48 bp的5个重复和6个重复等位基因(长重复等位基因)存在传递不平衡(χ2＝10.57,P＝0.032,χ2＝6.13,P＝0.01).结论 DRD4 exonⅢ48 bpVNTR长重复等位基因与合并ADHD的抽动障碍存在关联,DRD4 exonⅢ48 bpVNTR长重复等位基因可能是中国人群合并ADHD的抽动障碍的遗传危险因素.

Transmission disequilibrium test of DRD4 exonⅢ48bp variant number tandem repeat polymorphism and tic disorder

OBJECTIVE: To investigate whether DRD4 exon III48 bp variant number tandem repeat(VNTR) polymorphism is associated with tic disorder. METHODS: One hundred and twenty-two nucleus families were collected using Structured clinical interview for genetic study of Tourette syndrome and related disorders for family-based association analysis of tic disorder and DRD4 exon III 48bp VNTR polymorphism. One hundred and twenty-two trios were divided into two groups: tic disorder group (82 trios of Tourette syndrome or chronic tic disorder, TS&CT) and tic disorder accompanied with attention deficit and hyperactivity disorder (ADHD) group (40 trios of Tourette syndrome or chronic tic disorder accompanied with ADHD, TS&ADHD). Transmission disequilibrium test (TDT), in addition to polymerase chain reaction and VNTR technique were conducted in 122 trios. RESULTS: There exist 5 alleles at this polymorphic locus in this sample including DRD4 exon III 48bp 2-6 repeats. No transmission disequilibrium was found between DRD4 exon III 48 bp VNTR and tic disorder (chi square=7.44, P 0.12); however, when the sample was divided into two groups, transmission disequilibrium was noticed between the cases of TS&ADHD and this locus by overall allele-wise analysis (chi square=11.74, P 0.02), and there exists transmission disequilibrium exclusively between 5 or 6 repeats of 48bp VNTR(longer alleles) by allele-wise analysis (chi square=10.57, P 0.032, chi square=6.13, P 0.01). No transmission disequilibrium was seen between TS&CT and DRD4 exon III 48bp VNTR(chi square=3.38, P 0.50). CONCLUSION: The results of this study have revealed an association between the longer alleles of DRD4 exon III 48bp VNTR polymorphism and tic disorder accompanied with ADHD, thus suggesting a possible genetic risk factor of tic disorder accompanied with ADHD in Chinese.