Genetic and Environmental Factors in Deletion Disorders

缺失性疾病中的遗传和环境因素

• 批准号: 6525231
• 负责人: Robert D Nicholls
• 金额: $ 28.42万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6525231
• 关键词: Prader Willi syndrome; X ray; artificial chromosomes; chromosome aberrations; chromosome deletion; cytogenetics; environmental exposure; flow cytometry; gene duplication; gene environment interaction; gene rearrangement; genetic mapping; genetic susceptibility; genetically modified animals; genomic imprinting; green fluorescent proteins; happy puppet syndrome; human genetic material tag; human tissue; laboratory mouse; molecular cloning; northern blottings; nucleic acid sequence; polymerase chain reaction

DESCRIPTION (Investigator's abstract): A genomic disorder occurs de novo in region-specific repeats. Prototypic of genomic disorders are Prader-Willi and Angelman syndromes (PWS and AS), which arise in -1/7,500 births from a 4 Mb deletion of chromosome 15q11-q13. Our recent studies have shown the presence of 2-5 copies of paralogous sequences (duplicons) at or near each of a distal and two proximal PWS/AS breakpoint hotspots. The duplicons are derived in large part from genomic duplications of a novel gene (HERC2), while the tight clustering of breakpoints suggests a specific recombination mechanism leads to these deletions. We hypothesize that these duplicated sequences are involved in inter- and intra-chromosomal misalignment and homologous recombination, and that transcription of the duplicons in germ cells facilitates the recombination process. Finally, paternal occupational exposure to hydrocarbons has been associated with PWS, and we have shown that UV, X-rays, hydrocarbons and other chemicals enhance recombination of a similar genomic duplication in mice. Therefore, both genetic and environmental factors appear to predispose to chromosomal deletion events in PWS and AS. We propose four Specific Aims to examine the molecular mechanisms, and role of genetic and environmental susceptibility, in chromosome 15q1 1-q13 rearrangements: Aim 1. To determine the structure (number, orientation, sequence, gene content, and population variation) of HERC2-duplicons at 15Q11 and 15q13 by molecular cytogenetic and sequence echnologies. Aim 2. To identify sequence-specific hotspot(s) for chromosome recombination, we will clone and sequence deletion breakpoints using two novel assays, one detecting aberrant HERC2-related transcripts, and sequencing / informatics. Aim 3. We will examine genetic susceptibility (effect of inter-repeat distance, transcription and number of repeat copies) to intra- and inter-chromosomal deletion using a HERC2-GFP duplication model, including hotspot sequences (Aim 2), with assessment of the male germ cell rearrangement frequency using flow cytometry to detect GFP-tagged recombinants. Aim 4. We will determine whether environmental factors enhance the frequency of germ line recombination within Hprt- and HERC2-duplication mouse models, and similarly will examine genetic susceptibility using Ku80 about and p53- mice deficient in recombination pathways. These studies will identify the structure, variation and molecular pathological mechanisms underlying rearrangement of complex duplicated sequences in the mammalian germ line. Identification of environmental risk factors for germ line chromosome deletions may allow prevention of pre-conceptional exposure in the human population.

描述（研究者的摘要）：基因组障碍从头开始 区域特异性重复。基因组疾病的原型是prader-willi和 Angelman综合征（PWS和AS），在4 MB中以-1/7,7,500的出生产生 15q11-Q13染色体的删除。我们最近的研究表明 在远端或附近或附近的2-5个副序列（重复）和 两个近端PWS/作为断点热点。副词大大得出 来自新基因（HERC2）的基因组重复的一部分，而紧密 断点的聚类表明，特定的重组机制导致 这些删除。我们假设这些重复的序列与 染色体内和染色体内的未对准和同源重组，以及 生殖细胞中副词的转录有助于重组 过程。最后，父亲职业暴露于碳氢化合物 与PW相关，我们已经证明了紫外线，X射线，烃和其他 化学物质增强了小鼠类似基因组复制的重组。 因此，遗传因素和环境因素似乎都易于 PWS和AS中的染色体缺失事件。我们提出了四个具体目标 检查分子机制以及遗传和环境的作用 易感性，在15q1染色体中1-Q13重排：目标1。 结构（数量，方向，序列，基因含量和种群 通过分子细胞遗传学和 序列回声。目标2。确定序列特异性热点 染色体重组，我们将使用使用的序列删除断点和序列删除断点 两种新颖的测定法，一个检测异常的HERC2相关笔录，以及 测序 /信息学。目标3。我们将检查遗传敏感性（效应 重复间距离，转录和重复副本的数量） 使用HERC2-GFP复制模型，包括 热点序列（AIM 2），评估男性生殖细胞重排 使用流式细胞仪检测GFP标记的重组者的频率。目标4。我们 将确定环境因素是否会增强种系的频率 HPRT-和HERC2填充鼠标模型中的重组，类似地 将使用KU80和p53-小鼠检查遗传敏感性 重组途径。这些研究将确定结构，变化 和复合物重排的基础分子病理机制 在哺乳动物生殖系中重复的序列。识别 生殖系染色体缺失的环境风险因素可能允许 预防人口孕前的暴露。