注意缺陷多动障碍与多巴胺D4受体和多巴胺载体蛋白基因多态性的关系

目的：探讨中国汉族人群中，注意缺陷多动障碍(ADHD)与多巴胺D4受体基因(DR／M)第3外显子48bp和多巴胺载体蛋白基因(DAT1)非编码区40bp可变数目顺向重复(VNTR)多态性的关系。方法：对340个ADHD患儿，202个ADHD核心家系和226个对照分别就DRD4 48bp VNTR和DAT1 40bp VNTR多态性进行检测，并进行ETDT、HHRR和病例对照的关联分析。结果：所测人群中的DRD4 48 bp的重复次数是2—6次，最常见的等位基因是4次重复(77％)和2次重复序列(19．4％)；未发现7次重复序列或更长的片段。DAT1 40 bp的重复次数是6—7和9-11次，其中10次重复序列最常见(90．7％)。在ADHD患儿中，长重复等位基因(DRD4的4—6次和DAT1的11—12次重复序列)比对照组多。未发现ADHD和DRD4的7次重复等位基因或DAT1的10次重复等位基因之间存在关联。结论：DRD4(按照性别分层后)和DAT1的长重复等位基因可以增加中国汉族儿童罹患ADHD的危险性。

Association studies of dopamine D4 receptor gene and dopamine transporter gene polymorphisms in Han Chinese patients with attention deficit hyperactivity disorder

OBJECTIVE: To investigate association of the 48 bp variable number of tandem repeat (VNTR) polymorphism in the D4 receptor gene (DRD4) exon 3 and 40 bp VNTR polymorphism in the dopamine transporter gene (DAT1) 3' untranslated region with attention deficit hyperactivity disorder (ADHD) in Han Chinese children. METHODS: The study samples were comprised of 340 ADHD children, 226 unrelated controls and 202 integrated ADHD trios (included proband and biological parents). The polymorphisms consisted of 48 bp VNTR in exon 3 of DRD4, and 40 bp VNTR in the 3' untranslated region of DAT1. Associations of polymorphisms with ADHD and its subtypes were examined by: (i) comparing cases and controls; and (ii) using family-based association study in an extension of exact transmission-disequilibrium test (ETDT) and haplotype-based haplotype relative risk (HHRR). RESULTS: The repeat numbers at the DRD4 48 bp locus ranged from 2-6 repeats in the Han Chinese controls, with the most common being the 4-repeat (77%) and 2-repeat (19.4%) alleles. Neither the 7-repeat allele nor longer repeats were found. For the DAT1, the repeat numbers at the 40 bp locus ranged from 6-7 repeats and 9-11 repeats. The 10-repeat allele was the most frequent (90.7%). The long-repeat alleles of DRD4 (ranging from 4-6 repeats) and DAT1 (ranging from 11-12 repeats), were present more frequently in ADHD probands than in controls. Our primary analyses failed to replicate the associations between ADHD and 7-repeat allele of DRD4 and the 10-repeat allele of DAT1. CONCLUSION: The long-repeat alleles of DRD4 (after a stratification by gender) and DAT1 may increase the risk for ADHD in Han Chinese children.