Epigenetic Variation and Childhood Asthma in Puerto Ricans

描述（由申请人提供）：波多黎各（PR）儿童的哮喘患病率、发病率和死亡率在美国所有族裔群体中最高。最近的证据表明，在没有DNA序列改变的情况下发生的基因表达的遗传和/或新生变化（表观遗传）影响哮喘的发病机制。与大量的遗传学研究相比，很少有研究检查哮喘的表观遗传学。研究得最好的表观遗传机制是DNA甲基化，即在胞嘧啶残基上共价添加甲基，主要发生在CpG位点（即胞嘧啶在鸟嘌呤旁边的DNA序列）。我们假设与免疫反应和肺功能相关的基因中/附近CpG位点的DNA甲基化影响了PR儿童哮喘的发病机制。为了验证这一假设，我们将首先使用来自白细胞（wbc）和鼻上皮细胞的DNA，对40对6至14岁的PR单卵双胞胎（20对哮喘不一致的MZ双胞胎和20对哮喘一致的MZ双胞胎）中的80名成员进行甲基化（GWM）和哮喘的全基因组研究。在这项双胞胎研究的同时，我们将在a) 760例患有（病例，n=380）和未患有（对照组，n=380）哮喘的PR儿童中进行GWM和哮喘及其中间表型（肺功能测量和过敏标志物），使用来自白细胞的DNA， b) 500例患有（n=250）和未患有（n=250）哮喘的PR儿童中使用来自鼻上皮的DNA （Specific Aim 2）。然后，我们将评估选择的环境/生活方式（EL）暴露（环境烟草烟雾、维生素D不足和母亲/儿童心理社会压力）是否与Sp. Aim 2 （Specific Aim 3a）的顶级甲基化结果相关。最后，我们将通过在一部分研究参与者中进行焦磷酸测序测定和基因表达研究来验证我们先前目标中选择的甲基化测量。然后，我们将在独立队列中进行重复研究（Asthma BRIDGE [Specific Aim 3b]）。该建议应确定PR儿童哮喘（包括环境诱发哮喘）的新表观遗传标记。为了实现这一目标，我们组建了一支经验丰富的多学科研究团队。

DESCRIPTION (provided by applicant): Puerto Rican (PR) children have the highest prevalence, morbidity and mortality from asthma of all ethnic groups in the United States. Recent evidence suggests that heritable and/or de novo changes in gene expression that occur without alterations in DNA sequence (epigenetic) influence the pathogenesis of asthma. In contrast to a large number of genetic studies, few studies have examined the epigenetics of asthma. The best studied epigenetic mechanism is DNA methylation, the covalent addition of a methyl group to a cytosine residue occurring mostly in a CpG site (i.e., DNA sequence with a cytosine next to a guanine). We hypothesize that DNA methylation of CpG sites in/near genes relevant to immune response and lung function influence the pathogenesis of asthma in PR children. To test this hypothesis, we will first conduct a genome-wide study of methylation (GWM) and asthma in 80 members of 40 pairs of PR monozygotic (MZ) twins ages 6 to 14 years (20 pairs of MZ twins discordant for asthma and 20 pairs of MZ twins concordant for asthma) using DNA from white blood cells (WBCs) and nasal epithelial cells (Specific Aim 1). In parallel with this twin study, we will conduct a GWM and asthma and its intermediate phenotypes (lung function measures and allergy markers) in a) 760 PR children with (cases, n=380) and without (controls, n=380) asthma using DNA from WBCs, and b) 500 PR children with (n=250) and without (n=250) asthma using DNA from nasal epithelium (Specific Aim 2). We will then assess whether selected environmental/lifestyle (EL) exposures (environmental tobacco smoke, vitamin D insufficiency and maternal/child psychosocial stress) are associated with the top methylation findings from Sp. Aim 2 (Specific Aim 3a). Finally, we will validate selected methylation measurements from our prior aims by conducting pyrosequencing assays and gene expression studies in a subset of study participants. We will then then conduct replication studies in an independent cohort (Asthma BRIDGE [Specific Aim 3b]). This proposal should identify novel epigenetic markers of asthma (including environmentally-induced asthma) in PR children. To achieve this goal, we have assembled an experienced multidisciplinary research team.