Genetic Modulation of Glaucoma

描述(由申请人提供)：在这项提案中，我们使用我们扩大的BXD重组近交系菌株集来识别参与调节青光眼严重程度的基因位点。我们的方法结合了全面的临床和实验室检查，以及对过去10年产生的全部81个BXD系的微阵列分析，明确了研究眼病和青光眼的遗传学的目的。BXD的亲本菌株之一DBA/2J会发展为年龄相关性青光眼，在此之前会出现虹膜萎缩和色素弥散。虽然两个基因Tryp1和GPNMB的突变等位基因导致了D2的虹膜疾病，但文献强烈表明，这些突变不足以导致青光眼。具体地说，将这两个突变等位基因导入BXD的另一个亲本菌株C57BL/6J，会导致对视神经损伤的显著抵抗。这表明导致色素分散的基因以外的其他基因影响青光眼的表型。目前的建议描述了定义修饰基因座的独特机会。在目标1中，我们验证了这样的假设，即Tryp1和GPNMB的组合突变不足以导致青光眼表型的所有方面。如果我们的假设是正确的，我们希望看到疾病的严重程度不仅仅取决于这两个突变的等位基因。我们已经发现了多种BXD菌株，在这些菌株中，眼压和遗传二倍型没有相关性。随着我们系统地检查所有BXD毒株并建立表型和二倍型之间的关系，我们完全期待发现更多的毒株，这些毒株违背了简单的双基因座疾病模型的预期。在目标2中，我们定义了调节青光眼严重程度的基因座和基因。为此，我们将识别和评估调控青光眼表型严重程度的基因座内的候选基因。我们将利用我们新的D2全基因组鸟枪序列(UTHSC在2009年生成的约50倍短读报道)以及我们也生成的大量全眼和全视网膜表达数据集，作为这项工作的前奏。我们希望使用最先进的生物信息学方法和传统的分子分析方法有效地提名和评估候选青光眼基因。在目标3中，我们使用双向翻译。我们使用人类青光眼患者队列来测试来自Aim 2的候选小鼠的翻译有效性。Wiggs博士和他的同事将使用在Aim 2中提名的候选青光眼基因进行重点基因关联研究。具体地说，我们使用围绕人类染色体同线区域的标记的关联分析。在双向反向翻译中，我们(MMJ和LL)将评估来自临床队列的已知、新的和候选的青光眼基因，并确定这些变异是否以及如何与BXD中的青光眼相关特征相关。结合来自小鼠和人类青光眼研究的最重要的候选基因，我们将生成易感候选基因、连锁表型和相关机制的分子和统计模型。 与公共卫生相关：青光眼是一种高度流行的疾病，如果不加以控制，会导致不可逆转的视力丧失。在大多数病例中，疾病的潜在原因尚不清楚，因此治疗选择仅限于降低眼压。我们建议的研究结果将确定调节青光眼严重程度的基因位点，以扩大这一稀少的已知与这种疾病有关的基因清单。

DESCRIPTION (provided by applicant): In this proposal, we use our enlarged set of BXD recombinant inbred strains to identify gene loci that are involved in modulating the severity of glaucoma. Our approach combines a thorough clinical and laboratory examination, and microarray analysis of the entire set of 81 BXD lines generated over the last 10 years with the express purpose of studying the genetics of eye disease and glaucoma. One of the parental strains of BXD, DBA/2J, develop an age-related glaucoma that is preceded by iris atrophy and pigment dispersion. While mutant alleles of two genes, Tryp1 and Gpnmb, cause the iris disease in D2, the literature strongly suggests that these mutations are not sufficient to cause glaucoma. Specifically, introgression of both mutant alleles onto C57BL/6J, the other parent strain of BXD, results in a marked resistance to optic nerve damage. This indicates that genes other than those that cause pigment dispersion influence the glaucomatous phenotype. The current proposal describes a unique opportunity to define the modifying loci. In Aim 1, we test the hypothesis that the combined mutations in Tryp1 and Gpnmb are not sufficient to cause all aspects of the glaucoma phenotype. If our hypothesis is true, we expect to see that the severity of disease is not solely dependent on the two mutant alleles. We have already identified multiple BXD strains in which IOP and genetic diplotype are not correlated. As we systematically examine all BXD strains and establish relations between phenotype and diplotype, we fully expect to find additional strains that defy expectations of a simple two-locus disease model. In Aim 2, we define loci and genes that modulate glaucoma severity. To do so, we will identify and evaluate candidate genes within loci that modulate the severity of the glaucoma phenotype. We will exploit our new whole genome shotgun sequence for D2 (about >50x short read coverage generated at UTHSC in 2009) along with massive whole eye and whole retina expression datasets that we have also generated as a prelude to this work. We expect to efficiently nominate and evaluate candidate glaucoma genes using state-of-the-art bioinformatic methods and conventional molecular assays. In Aim 3, we use bidirectional translation. We test the translational validity of mouse candidates from Aim 2 using cohorts of human glaucoma patients. Dr. J. Wiggs and colleagues will perform focused gene association studies using candidate glaucoma genes nominated in Aim 2. Specifically, we use association analyses of markers encompassing syntenic regions of human chromosomes. In reciprocal reverse translation, we (MMJ and LL) will evaluate known, new, and candidate glaucoma genes from clinical cohorts and determine if and how these variants are associated with glaucoma- associated traits in BXDs. Combining the top priority gene candidates from both mouse and human glaucoma studies, we will generate molecular and statistical models of susceptibility candidate genes, linked phenotypes, and associated mechanisms. PUBLIC HEALTH RELEVANCE: Glaucoma is a highly prevalent group of diseases that, if uncontrolled, causes irreversible loss of vision. The underlying cause of the disease is not known in the majority of cases, therefore treatment options are limited to lowering the intraocular pressure. Outcomes of our proposed investigations will identify gene loci that modulate glaucoma severity to expand this sparse list of genes that are known to contribute to this disease.