Human neurobehavioral phenotypes associates with the extended PWS/AS domain

描述(由申请人提供)： 项目摘要/摘要。这项建议的长期目标是定义染色体15q11-q13上从断点1(BP1)到断点5(BP5)的扩展Prader-Willi/Angelman结构域的基因型/表型相关性，特别强调BP4-BP5区域，其中缺失与智力低下、自闭症、癫痫、精神分裂症和双相情感障碍有关。基因分析将专注于删除或复制多个连续基因的拷贝数变异(CNV)，以及单个基因内的点突变，特别是CHRNA7。该项目以前的工作重点是Prader-Willi综合征(PWS)和Angelman综合征(AS)，分别由父亲和母亲的缺乏症引起，位于该区域的中央部分。目前正在扩大研究范围，以包括该区域重复引起的自闭症，并研究与该区域侧翼部分相关的表型，BP1至BP2和BP4至BP5。染色体15q13.3(BP4-BP5)的缺失移除了六个相连的基因，较小的缺失移除了CHRNA7和相邻基因的一个外显子。目的1是确定BP4-BP5区的基因型/表型关系，重点是CHRNA7基因。目的1a通过病例对照研究确定15q13.3和CHRNA7重复是病理的还是良性的。目的1b是确定与15q13.3和CHRNA7缺失相关的表型异质性的基础，主要但不完全集中在各种遗传修饰效应上。目的1c是在特别高风险的样本中寻找CHRNA7的功能缺失突变，例如同时患有癫痫和精神分裂症或同时患有癫痫和双相情感障碍的NIMH样本。目的2是确定BP1-BP2区及其4个基因的基因型/表型关系。目的3是确定BP1/BP2到BP3区域复制的亲本的分子基础，BP1/BP2到BP3区域的重复通常会在母亲染色体上引起自闭症，而在父亲染色体上通常是良性的。这一目标将强调对人脑组织的表达分析(越来越依赖RNA-Seq)和表观遗传学研究，比较15q11-q13区域的复制与对照。目的4是确定snoRNA HBII-85簇的功能，因为现在有相对强有力的证据表明，父亲对该snoRNA簇的缺乏导致了PWS表型的主要成分。这一目标将集中在缺乏HBII-85表达的人和小鼠大脑中的全基因组表达分析以及选择性剪接和RNA编辑(再次使用RNA-Seq)。基于生物信息学分析，已经确定了一系列目标候选基因，并计划进行进一步的生物信息学分析。这些候选基因的表达将在对照和来自小鼠和人的PWS脑中进行研究，使用RT-PCR来分析选择性剪接和RNA编辑。 公共卫生相关性： 项目叙事。这个项目具有很强的医学意义，首先是因为这个染色体区域的遗传变异，特别是一个基因(CHRNA7)的遗传变异是常见的，肯定会导致智力低下、自闭症、癫痫、精神分裂症和躁郁症。第二个很强的医学相关性是自闭症，因为母亲染色体上这个区域的重复会导致自闭症，而父亲染色体上的重复不会，理解这种差异的分子基础应该会对自闭症的原因有相当大的帮助，这些原因不是由DNA序列的变化引起的。第三，snoRNAs是非编码RNA上的一种研究很少的形式，了解它们的功能很重要，因为缺乏一类snoRNAs是Prader-Willi综合征的主要原因，可能与肥胖有关。

DESCRIPTION (provided by applicant): Project Summary/Abstract. The long-term objectives of this proposal are to define genotype/phenotype correlations for the extended Prader-Willi/Angelman domain on chromosome 15q11-q13 that stretches from Breakpoint 1 (BP1) to Breakpoint 5 (BP5), with special emphasis on the BP4-BP5 region where deletions are associated with mental retardation, autism, epilepsy, schizophrenia, and bipolar disorder. Genetic analysis will focus both on copy number variations (CNVs) deleting or duplicating multiple contiguous genes and on point mutations within individual genes, especially CHRNA7. Previous work on this project has focused on Prader- Willi syndrome (PWS) and Angelman syndrome (AS), caused by paternal and maternal deficiency, respectively, for the central portion of the domain. The focus is now being broadened to include autism caused by duplications of this region and to study phenotypes associated with the flanking portions of the domain, BP1 to BP2 and BP4 to BP5. Deletions of chromosome 15q13.3 (BP4-BP5) remove six contiguous genes, and a smaller deletion removes CHRNA7 and one exon of an adjacent gene. Aim 1 is to determine genotype/phenotype relationships for the BP4-BP5 region with emphasis on the CHRNA7 gene. Aim 1a is to determine if the 15q13.3 and CHRNA7 duplications are pathological or benign using case control studies. Aim 1b is to identify the basis for the phenotypic heterogeneity associated with the 15q13.3 and CHRNA7 deletions focusing primarily but not exclusively on various genetic modifier effects. Aim 1c is to search for loss-of- function point mutations in CHRNA7 in particularly high risk samples such NIMH samples with both epilepsy and schizophrenia or both epilepsy and bipolar disorder. Aim 2 is to determine genotype/phenotype relationships for the BP1-BP2 region and the four genes therein. Aim 3 is to determine the molecular basis for the parent of origin effects of duplications of the BP1/BP2 to BP3 region which typically cause autism when on a maternal chromosome and are usually benign when on the paternal chromosome. This aim will emphasize expression analysis (increasingly relying on RNA-Seq) and epigenetic studies of human brain tissue comparing duplications of the 15q11-q13 region with controls. Aim 4 is to determine the function of the snoRNA HBII-85 cluster, because there is now relatively strong evidence that paternal deficiency for this snoRNA cluster causes the major components of the PWS phenotype. This aim will focus on genome-wide analysis of expression and on alternative splicing and RNA editing (again using RNA-Seq) in human and mouse brain lacking expression of HBII-85. A series of target candidate genes have been identified by others based on bioinformatic analysis, and further bioinformatic analysis is planned. The expression of these candidate genes will be studied in control and PWS brain from mouse and human using RT-PCR to analyze alternative splicing and RNA editing. PUBLIC HEALTH RELEVANCE: Project Narrative. This project has strong medical relevance, first because genetic variation in this chromosomal region and especially in one gene (CHRNA7) is common and definitely can cause mental retardation, autism, epilepsy, schizophrenia, and bipolar disorder. The second strong medical relevance is to autism because duplications of this region on the maternal chromosome cause autism, while duplications on the paternal chromosome do not, and understanding of the molecular basis for this difference should shed considerable light on the causes of autism that are not caused by changes in DNA sequence. Third, snoRNAs are a little studied form on noncoding RNAs, and understanding their function is of importance, because deficiency of one class of snoRNAs is a major component of the cause of Prader-Willi syndrome and likely is relevant to obesity.