DAT1和DRD4基因启动子区甲基化水平与注意缺陷多动障碍发病的关联研究

Association of methylation status of CpG islands in DAT1 and DRD4 genes with attention deficit hyperactivity disorder

目的探讨注意缺陷多动障碍（attention deficit hyperactivity disorder，ADHD）患儿和正常儿童在多巴胺转运体基因（DAT1／SLC6A3）、多巴胺D4受体基因（DRD4）启动子区CpG岛甲基化状态的差异，旨在从表观遗传学角度进一步阐明ADHD的遗传学机制。方法收集111例ADHD患者及118例对照组儿童的外周血及一般人口学资料，采用亚硫酸氢钠测序法，检测111例ADHD患者及118例对照儿童的DAT1基因、DRD4基因的启动子区CpG岛目标片段的甲基化状态。结果病例组和对照组在DAT1和DRD4启动子区总体发生甲基化的频数比例的均差异无统计学意义（P〉0．05）；DAT1启动子区第17个CpG位点、DRD4启动子区第8个CpG位点病例组发生甲基化的频数比例（23．42％、64．86％）较对照组高（11．86％、47．46％）（均P〈0．05）。在所有样本中，DAT1启动子区发生甲基化的频数比例男性高于女性（P〈0．05），DRD4启动子区则女性高于男性（P〈0．05）；病例组中DAT1启动子区发生甲基化的频数比例男性高于女性（P〈0．05），而对照组中则为DRD4启动子区女性高于男性（P〈0．05）。在所有样本中，〉7岁年龄组在DAT1启动子区发生甲基化的频数比例高于≤7岁组（P〈0．05）；病例组中〉7岁年龄组在DAT1启动子区发生甲基化的频数比例亦高于≤7岁组（P〈0．05）。结论DAT1及DRD4基因启动子区CpG岛甲基化状态可能与ADHD易感性相关；不同性别、年龄个体的DAT1及DRD4基因启动子区CpG岛甲基化状态存在差异。

Objective To explore the difference of methylation status of CpG island in promoter region of DAT1 and DRD4 genes between children with attention deficit hyperactivity disorder （ADHD） and normal controls, and further understand the pathogenesis of ADHD from a epigenetics point of view. Methods 111 ADHD patients and 118 normal controls were enrolled in the present study. The demographic data and peripheral venous blood were collected from both groups. Bisuffite genomic sequencing （BGS） was used to confirm the methylation status of every CpG site in promoter region of DAT1 and DRD4 genes. Results No significant differences were found between ADHD patients and normal controls on percentage of methylated CpG sites in total CpG islands for both DAT1 and DRD4 （P〉0.05）. However,the percentage of methylation in No. 17 CpG site for DAT1 and No. 8 CpG site for DRD4 was higher in ADHD patients （23.42% and 64.86% respectively）compared with that in normal controls （11.86% and 47.46% respectively）（P〈0.05）.In all samples,the percentage of methylated CpG site in total CpG island for DAT1 was higher in males compared with that in females （P〈 0.05 ） , whereas that for DRD4 was higher in females compared with that in males （P〈0.05） ; the same gender difference on methylation level for DAT1 was also found in ADHD patients and for DRD4 in normal controls（P〈0.05 ）. In all samples and in ADHD patients, percentage of methylated CpG site in total CpG island for DAT1 was higher in individuals over 7 years old compared with that in individuals younger than or equal to 7 years old（P〈0.05）. Conclusions Methylation status of CpG island in DAT1 and DRD4 genes promoter region might correlate with ADHD susceptibility.Methylation status of CpG island in DAT1 and DRD4 genes show differences in different age span and sex.