High-resolution Genetic Mapping of Maternal Effects and Epistatic Suppressors of Congenital Heart Disease Risk

项目摘要/摘要 先天性心脏病(CHD)是最常见的先天畸形，可导致明显的 新生儿发病率和死亡率。尽管外科技术的巨大进步降低了新生儿的冠心病死亡率 而孩子们，这些患者并没有痊愈。这些儿童中的许多人长大后经历了严重的疾病和 成年后的截短寿命。很明显，我们需要战略来将我们的努力从 以干预为主，以预防为主。这一努力的第一步是了解CHD的原因。 令人惊讶的是，环境和突变估计可以解释不到三分之一的CHD病例。在许多 然而，在某些情况下，即使重要的心脏基因发生突变，心脏缺陷也不会发生。这突出了 遗传修饰物在冠心病发病机制中的关键作用。识别这些修饰基因的尝试已经有了 在人类身上取得的边际成功。这促使我们寻找动物模型，在动物模型中，我们可以控制效果 环境和遗传的关系。 我们的小鼠模型通过Nkx2-5杂合突变在易感人群中复制了CHD风险， 一种重要的心脏转录因子。然后，我们使用近交系杂交和数量遗传方法来 确定改变Nkx2-5+/-小鼠冠心病风险的基因多态。通过这个模式系统，我们 无意中证实了人类的观察结果，即年长母亲的后代患冠心病的风险增加 即使排除了非整倍体的可能性。我们还确定，这种风险是由于年迈母亲的内在因素，而不是年老的母亲。 鸡蛋。值得注意的是，对于年迈的母亲来说，自愿锻炼足以将冠心病风险降低到基线水平。 随后的研究表明，母亲衰老风险的大小因遗传而异。 我们老鼠的背景。这表明年龄风险是调节母体因素的数量性状， 这可能会增加或降低患冠心病的风险。在专注于以下风险修正因素的单独实验中 在易感个体中，我在多只小鼠中发现了作为冠心病风险上位抑制因子的基因位点 人口。如果我们能够确定负责的基因，并模仿母体锻炼或 如果有了保护性基因座，我们就可以将这些益处传递给普通人群。我们过去的实验并没有 被设计用来检测单个基因。因此，与其推测决定产妇年龄的基因-- 冠心病的相关风险和上位性抑制，我们选择了谨慎和公正的方法来确定 这些基因。我们已经与詹姆斯·切弗鲁德的实验室合作，使用高分辨率、先进的 交叉作图群体，以确定CHD修饰基因座，几乎达到单基因分辨率。这项研究将是 第一个以高分辨率绘制出改变冠心病风险的新基因和变异的图谱，这些结果将作为 为未来预防先天性心脏病的研究提供了跳板。 我们提出以下具体目标： 目的1：确定可改变母亲年龄相关冠心病风险的高分辨率基因座。 目的2：定位高分辨率基因座并检测后代冠心病风险的上位性抑制基因。

PROJECT SUMMARY / ABSTRACT Congenital heart disease (CHD) is the most common congenital anomaly, which leads to significant morbidity and mortality in newborns. Although great surgical advances have reduced CHD mortality in newborns and children, these patients are not cured. Many of these children grow up and experience serious morbidity and truncated lifespans as adults. It has become evident that we need strategies to move our efforts away from intervention and toward prevention. The first step in this endeavor is to understand the causes of CHD. Surprisingly, environment and mutations are estimated to explain less than one-third of CHD cases. In many cases, however, even when a vital cardiac gene is mutated, a heart defect does not occur. This highlights the critical role that genetic modifiers have in CHD pathogenesis. Attempts to identify these modifier genes have had marginal success in humans. This motivated us to look toward animal models, in which we can control the effects of environment and genetics. Our mouse model replicates CHD risk in susceptible people through a heterozygous mutation in Nkx2-5, an essential cardiac transcription factor. We then use inbred strain crosses and quantitative genetic methods to identify genetic polymorphisms that modify CHD risk in Nkx2-5+/- mice. Through this model system, we inadvertently confirmed observations in humans that the offspring of older mothers have an elevated risk for CHD even after ruling out aneuploidy. We also determined that this risk is due to factors within old mothers, not old eggs. Remarkably, voluntary exercise for the aging mother is sufficient to reduce CHD risk to baseline levels. Subsequent studies demonstrated that the magnitude of the maternal aging risk varied according to the genetic background of our mice. This indicates that the age risk is a quantitative trait that regulates maternal factors, which can either inflate or suppress the risk of CHD. In separate experiments focused on risk modifiers within susceptible individuals, I discovered genetic loci that act as epistatic suppressors of CHD risk in multiple mouse populations. If we were able to identify the genes responsible and mimic the effects of maternal exercise or protective genetic loci, we could translate these benefits to the general population. Our past experiments were not designed to detect individual genes. So instead of speculating about the genes responsible for the maternal age- associated risk and epistatic suppression of CHD, we have chosen a prudent and unbiased approach to identify these genes. We have partnered with the laboratory of James Cheverud to use a high-resolution, advanced intercross mapping population to identify CHD modifier loci to nearly single-gene resolution. This study will be the first to map novel genes and variants that modify CHD risk at high-resolution, and these results will serve as a springboard for future research into congenital heart disease prevention. We propose these specific aims: AIM 1: Identify high-resolution genetic loci that modify the maternal age-associated risk of CHD. AIM 2: Map high-resolution genetic loci and detect epistatic suppressors of CHD risk in the offspring.