Structural Genetic Variation in Asthma

描述(由研究人员提供)：拷贝数变异(CNV)是由大DNA片段组成的结构性遗传变异，其数目因个体而异。这些大规模得失的重要性直到最近才被认识到：CNV非常常见，占总遗传变异的很大比例，并对表型变异和疾病易感性有很大贡献。在美国，哮喘影响着1700多万人，是导致发病的一个重要原因。尽管20多个针对哮喘易感基因的全基因组遗传调查的累积结果已经成功地发现了几个新的哮喘基因，但这些先前的研究都没有评估CNV在哮喘发病机制中的作用。在对400个哮喘家庭的约500,000个单核苷酸多态基因进行全基因组、家系筛选的初步研究中，我们的团队已经确定了几个包含已知结构变异的基因组区域，这些区域与哮喘易感性密切相关，其中包括几个包含先前发现的哮喘基因的区域。根据这些初步数据，我们假设共同的结构基因组变异在多个人群中对哮喘流行具有重要的易感性。我们提出了4个具体目标来检验这一假说。在具体目标1中，我们将使用Affymetrix SNP6.0微阵列生成的高分辨率CNV基因数据，在患有儿童哮喘的非西班牙裔白人家庭中进行一项基于家庭的全基因组相关性研究。然后，我们将从技术上验证使用高密度寡核苷酸阵列和定量PCR方法确定的与哮喘相关的前20个CNV区域。在具体目标2中，我们将在三个独立的哮喘队列(总样本量约6000名受试者)中复制这些关联，包括西班牙裔白人和非西班牙裔黑人人口。在具体目标3中，我们将对候选基因进行测序，并在哮喘队列中进行后续的SNP基因分型和关联测试，以确定两个复制的哮喘相关CNV区域的哮喘相关核苷酸变异。在特定的目标4中，我们将评估哮喘相关CNV对180名哮喘患者中位于哮喘相关CNV内或附近的候选基因的mRNA基因表达和靶蛋白表达水平的影响。该项目有很高的潜力来确定对哮喘的病理生物学至关重要的新的分子靶点用于治疗靶点。与公共卫生相关的结构遗传变异由大的DNA片段组成，其数量因个体而异。该项目旨在确定导致哮喘发生的结构性遗传变异。我们建议在一组儿童哮喘患者中对这种变异进行全基因组调查，并对这些区域进行后续表征，并在代表美国三个主要种族群体的人群中进行复制研究。确定哮喘的遗传决定因素最终将导致新的治疗方法和诊断测试的发展。

DESCRIPTION (provided by investigator): Copy number variants (CNVs) are structural genetic variants consisting of large DNA segments whose number varies between individuals. The importance of these large-scale gains and losses has only recently been recognized: CNVs are extremely common, represent a large proportion of the total genetic variation, and contribute substantially to phenotypic variation and disease susceptibility. Asthma affects over 17 million people in the U.S. and represents a significant cause of morbidity. Though the cumulative results of more than 20 genome-wide genetic surveys for asthma susceptibility loci have successfully identified several novel asthma genes, none of these prior studies have assessed the role of CNVs in the pathogenesis of asthma. In preliminary studies using a genome-wide, family-based screen of ~500,000 single nucleotide polymorphism genotypes in 400 families with asthma, our group has identified several genomic regions harboring known structural variation that are strongly associated with asthma susceptibility, including several containing previously identified asthma genes. From these preliminary data, we hypothesize that common structural genomic variants confer important susceptibility to asthma prevalence in multiple populations. We propose 4 Specific Aims to test this hypothesis. In Specific Aim 1 we will perform a family-based genome-wide association study in non-Hispanic white families with childhood asthma using high-resolution CNV genotype data generated with Affymetrix SNP6.0 microarrays. We will then technically validate the top 20 asthma- associated CNV regions identified using high-density oligonucleotide arrays and quantitative PCR methods. In Specific Aim 2, we will replicate these associations in three independent asthma cohorts (total sample size ~6000 subjects), including Hispanic white and non-Hispanic black populations. In Specific Aim 3 we will sequence candidate genes and perform follow-up SNP genotyping and association testing in the asthma cohorts to identify asthma-related nucleotide variation in 2 replicated asthma-associated CNV regions. In Specific Aim 4 we will evaluate the impact of asthma-associated CNVs on mRNA gene expression and target protein expression levels for candidate genes residing within or near the asthma-associated CNVs in 180 asthmatics. This project has high potential to identify novel molecular targets critical to the pathobiology of asthma for therapeutic targeting. PUBLIC HEALTH RELEVANCE Structural genetic variants consist of large DNA segments whose number varies between individuals. This project aims to identify structural genetic variation that contributes to the development of asthma. We propose to conduct a genome-wide survey for such variation in a cohort of childhood asthmatics, with follow-up characterization of these regions and replication studies in populations representing the three major ethnic groups in the United States. Defining the genetic determinants of asthma will ultimately lead to the development of novel therapies and diagnostic tests.