Genetic Complexity and Modifiers of Hirschsprung Disease

描述(申请人提供)：先天性巨结肠(HSCR)是一种复杂的 导致远端固有神经节缺失的遗传性疾病 肠道，从而产生胃肠动力障碍。基因突变 几种基因中的任何一种都可以引起肠道无神经节细胞增多症，即 这种疾病的特点是。不完全外显与可变表现力 携带相同基因的家庭成员表现出的神经脊(NC)缺陷 基因突变提示多个基因调节HSCR的严重程度。小白鼠 HSCR模型对于识别 参与肠道神经系统(ENS)缺陷的发病机制。遗传 对小鼠突变体Sox10Dom的胚胎分析已经确定了这一作用 转录因子在ENS发育中的作用。我们对Sox10Dom小鼠的分析 在F1杂交和近交系菌株中证明了遗传背景对 肠道无神经节细胞增多症的严重程度。我们观察到的表型变异 模拟在人类HSCR同胞中看到的情况，并表明修饰性基因座影响 Sox10衍生物在小鼠和人体内的研究进展。在提议的实验中 我们将检验基因座之间的基因交互作用影响ENS的假设 发展。将使用Sox10Dom小鼠的同源品系来定义时间 遗传背景对肠源性NC的影响。具体来说，我们将 评估肠内NC在胚胎中的存活、增殖和迁移 Sox10Dom同源品系。以确定与表型有关的基因 Sox10Dom HSCR模型的变化，我们将评估它们之间的关联 候选修饰基因座等位基因与肠道神经节细胞缺乏症严重程度的关系 SOX10DOM动物保持在F1杂交背景上。潜在基因 相互作用将通过检查无神经节细胞增多症的严重程度在体内得到验证 在Sox10Dom与候选修饰基因座的突变体杂交中。我们的 初步分析已经确定了一种非常重要的相互作用 在Sox10和EDNRB之间，我们已经在 EDNRB侧翼区域。研究Sox10之间的生物相互作用 和EDNRB，我们将确定EDNRB基因座的序列变异。功能界别 将评估基因多态对EDNRB基因水平和功能的影响 在神经管(NT)和肠神经节培养中，来自我们的同源系。这些 实验是定义基因机制的统一策略的一部分 参与ENS发生发展的相互作用。

DESCRIPTION (provided by applicant): Hirschsprung disease (HSCR) is a complex genetic disorder that gives rise to absence of intrinsic ganglia in the distal intestine and consequently produces gastrointestinal dysmotility. Mutations in any one of several genes can give rise to the intestinal aganglionosis that is the hallmark of this disease. Incomplete penetrance and variable expressivity of the neural crest (NC) defects exhibited by family members carrying identical gene mutations suggests that multiple genes modulate HSCR severity. Mouse models of HSCR have been extremely valuable for identifying genes that participate in pathogenesis of enteric nervous system (ENS) defects. Genetic and embryonic analysis of the mouse mutant Sox10Dom has defined a role for this transcription factor in development of the ENS. Our analysis of Sox10Dom mice in F1 hybrid and inbred strains demonstrates that genetic background impacts severity of intestinal aganglionosis. The phenotypic variation we observe mimics that seen in human HSCR sibs and suggests that modifier loci influence development of Sox10 derivatives in mouse and man. In the proposed experiments we will test the hypothesis that gene interactions between loci impact ENS development. Congenic lines of Sox10Dom mice will be used to define the timing and effect of genetic background on the enteric NC. Specifically we will evaluate survival, proliferation, and migration of enteric NC in embryos from Sox10Dom congenic lines. To identify the genes responsible for the phenotypic variation in the Sox10Dom HSCR model we will evaluate association between alleles at candidate modifier loci and severity of intestinal aganglionosis in Sox10Dom animals maintained on an F1 hybrid background. Potential gene interactions will be validated in vivo by examining severity of aganglionosis in crosses between Sox10Dom and mutants at candidate modifier loci. Our preliminary analysis has already identified a highly significant interaction between Sox10 and EdnrB and we have identified Sox10 consensus binding sites in EdnrB flanking regions. To investigate the biological interaction between Sox10 and EdnrB we will identify sequence variants at the EdnrB locus. The functional effects of polymorphisms on levels of EdnrB mRNA and function will be evaluated in neural tube (NT) and enteric ganglia cultures from our congenic lines. These experiments are part of a unified strategy to define the mechanisms of gene interaction that participate in development and pathogenesis of the ENS.