MECHANISMS AND CONSEQUENCES OF CHROMOSOMAL ABNORMALITIES

染色体异常的机制和后果

• 批准号: 6387915
• 负责人: David H. Ledbetter
• 金额: $ 32.03万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-01 至 2003-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6387915
• 关键词: artificial chromosomes; biochemical evolution; chromosome aberrations; chromosome deletion; chromosome inversion; chromosome translocation; clinical research; cytogenetics; disease /disorder etiology; fluorescent in situ hybridization; gene expression; gene rearrangement; genetic disorder; genetic disorder diagnosis; genetic mapping; genetic polymorphism; genetic recombination; human genetic material tag; human subject; molecular cloning; nucleic acid sequence; pulsed field gel electrophoresis; sequence tagged sites

DESCRIPTION (Adapted from the Investigator's Abstract): Structural chromosomal rearrangements are an important cause of human genetic disorders associated with mental retardation and other human developmental abnormalities. The etiology of recurring constitutional chromosomal rearrangements such as deletions, duplications, and marker chromosome formation is poorly understood. The investigators seek to address this problem by a complete genomic and molecular characterization of the chromosome region 15q11-q13, which is associated with an unusually high frequency and diversity of recurring rearrangements including one of the most frequent interstitial deletions observed in humans (1/10,000-1/20,000 births). Due to genomic imprinting, paternal deletions produce Prader-Willi syndrome (PWS) and maternal deletions produce the distinct genetic disorders, Angelman syndrome (AS). This region is also involved in 50 percent of all supernumerary marker chromosomes, and less frequently in intrachromosomal duplications, triplications, and jumping translocations. Evidence now suggests the presence of four hotspots for chromosome breakage in this region: two proximal to the PWS/AS region and two distal. Complete molecular characterization of this region may lead to a more basic understanding of the mechanism of chromosomal rearrangements. Specific goals of the project include the development of a high-resolution physical map of the approximately 8 Mb (reduced in size by 2 Mb) chromosome segment 15cen-15q14 using YAC and BAC contigs and STS content mapping. The goal is 1 STS/50 kb. The map will be anchored at the chromosome 15 centromere by YAC and BAC walking to close the current 1-2cM gap (previously a 12 cM gap). Progress will be monitored by interphase FISH analysis and by genetic mapping in ovarian teratomas with newly developed STRs and/or SNPs. The four recurring breakpoints (hotspots) will be cloned and sequenced to test the hypothesis that multiple copies of a large duplicated gene cluster (200-600 kb) mediate intrachromosomal and interchromosomal rearrangements. Features of these sequences, such as copy number, distribution, and orientation will be analyzed in normal controls and parents of children with de novo abnormalities to assess polymorphism or to identify any specific predisposing factors or genomic rearrangements. These sequences will also be studied among other great ape species for evidence of "evolutionary hotspots" for chromosomal rearrangement. The proposed orientation of the 4 duplicated clusters (direct-inverted-direct-direct) provides a framework for proposing and testing specific models to account for the diverse rearrangements observed in chromosome 15. An extensive patient collection will be developed representing each class of rearrangement (deletion, duplication, triplication, marker chromosome, jumping translocation) and each of the 4 breakpoint hotspots. For each patient and class of abnormality, the investigators will determine the content, parental origin, and specific breakpoint as well as determine whether the rearrangements are due to meiotic unequal crossing-over or intrachromosomal events. Specific breakpoints will be determined by FISH and pulse field gel electrophoresis, followed by sequencing in selected cases. Development of rapid and precise breakpoint specific assays and methylation assays may facilitate patient analysis and clinical diagnosis.

描述（改编自调查员的摘要）：结构性 染色体重排是人类遗传疾病的重要原因 与智力低下和其他人类发展有关 异常。 重复出现的宪法染色体的病因 删除，重复和标记染色体等重排等重排 形成知之甚少。 调查人员寻求解决这个问题 通过完整的基因组和分子表征的问题 染色体区域15q11-Q13，与异常高有关 重新排列的频率和多样性，包括其中一个 在人类中观察到的最常见的间质缺失（1/10,000-1/20,000 出生）。 由于基因组印记，父亲缺失会产生prader-willi 综合征（PWS）和母体缺失产生独特的遗传 疾病，安吉尔曼综合症（AS）。 该地区也参与了50个 所有超级标记染色体的百分比，较少的频率 内骨体内重复，一式三份和跳跃易位。 现在有证据表明存在四个用于染色体破裂的热点 在该区域：两个靠近PWS/AS AS区域和两个远端。 完全的 该区域的分子表征可能会导致更基础 了解染色体重排机制。 该项目的具体目标包括发展高分辨率 大约8 MB的物理图（尺寸降低2 MB）染色体 段15CEN-15Q14使用YAC和BAC重叠群和STS内容映射。 这 目标是1 STS/50 KB。 该地图将锚定在15号染色体上 YAC和BAC的Centromere缩小当前1-2厘米间隙（以前 一个12厘米的间隙）。 进展将通过相间鱼分析和 带有新开发的STR和/或SNP的卵巢畸胎瘤中的遗传图。 四个重复的断点（热点）将被克隆并测序 测试一个假设，即大型重复基因簇的多个副本 （200-600 kb）介导伦敦体内和染色体重排。 这些序列的功能，例如复制号，分布和 方向将在正常对照中分析 从头异常评估多态性或确定任何特定的 诱发因素或基因组重排。 这些序列也将 在其他伟大的猿类中进行研究，以证明“进化 热点“用于染色体重排的热点。提出的4 重复的群集（直接直接直接导向）提供了一个框架 提出和测试特定模型以说明多样化 在15染色体中观察到的重排。广泛的患者收集 将开发代表每类重排（删除， 重复，三重，标记染色体，跳跃易位）和 四个断点热点中的每个。 每个患者和班级 异常，调查人员将确定父母的内容，父母的起源， 和特定的断点以及确定重排是否是 由于减数分裂不平等的跨越或鲜膜内事件。 具体的 断点将由鱼和脉冲场凝胶电泳确定， 然后在选定的情况下进行测序。 快速而精确的发展 断点特定的测定和甲基化测定可能有助于患者 分析和临床诊断。