X chromosome cDNA microarray Screening and Functional Study of Novel XLMR genes

描述(申请人提供)：智力低下(MR)是导致儿童和年轻人残疾的最常见原因，占总人口的2%-3%。MR患者往往需要长期的医疗和支持护理或服务，给家庭和社会积累了巨大的成本和负担。据估计，患有MR的每个人的平均终生成本超过100万美元。X-连锁精神发育迟滞(XLMR)发生在600名男性中就有1名，并且具有遗传异质性。在X染色体上的&gt；150-200个负责基因座中，已经克隆了&lt；60个基因。XLMR基因的鉴定对于诊断、咨询、预防、患者管理和合理开发有效的治疗方法至关重要。它还将提供对人类认知功能机制的洞察。我们的长期目标是了解X连锁精神发育迟滞的分子基础和机制。在这一应用中，我们希望利用我们使用人类X染色体基因芯片(XCM)识别新的XLMR基因的初步研究的令人兴奋的结果。这种XCM将被用于从XLMR男性的淋巴母细胞中筛选RNA，以识别显示转录水平显著变化的基因。这一策略是基于这样一个事实，即任何给定基因座上的一小部分突变(估计为&gt；30%)会导致稳定状态转录本的丰度发生戏剧性变化。该方法旨在检测由于启动子突变、基因缺失或复制、与移码突变相关的RNA剪接异常以及与无义介导的mRNA相关的无义突变等机制导致的导致mRNA丰度变化的突变。它的优点是可以快速筛选整个X染色体上的基因，而不需要大的家系。具体地说，我们将(1)使用XCM从XLMR男性中筛选120个淋巴母细胞系，以确定新的候选基因(2)通过对先证者和大量XLMR男性中新的候选基因进行测序来确定负责的遗传缺陷(3)对4-6个新的XLMR基因进行功能研究，以了解它们在人类认知中的生理作用以及这些基因的突变如何导致智力低下。研究结果将有助于提高我们对智力低下遗传原因的认识，并为认知功能障碍患者的诊断、遗传咨询、预防和临床护理制定合理的策略。

DESCRIPTION (provided by applicant): Mental retardation (MR) is the most common cause of handicaps in children and young adults and accounts for 2-3% in the general population. Patients with MR often require long-term medical and supportive care or services and accumulate enormous costs and burden to the families and the society. The average lifetime costs per person with MR were estimated to be more than $1 million. X-linked mental retardation (XLMR) occurs in 1 in 600 males and is genetically heterogeneous. Among the > 150-200 responsible loci on the X chromosome, <60 genes have been cloned. Identification of XLMR genes is essential for diagnosis, counseling, prevention, patient management, and rational development of effective therapy. It will also provide insight into the mechanism of human cognitive function. Our long-term goals are to understand the molecular basis and mechanism of X-linked mental retardation. In this application, we wish to capitalize on the exciting results from our pilot study of using a human X chromosome cDNA microarray (XCM) to identify novel XLMR genes. This XCM will be used to screen RNA from lymphoblasts of XLMR males to identify genes that show significant alterations in transcript levels. This strategy is based on the fact that a fraction of the mutations (estimated to be >30%) at any given locus result in dramatic alternations in the abundance of steady state transcripts. This approach is designed to detect mutations that result in a change in the abundance of mRNA due to mechanism such as promoter mutations, gene deletions or duplications, and abnormal RNA splicing associated with frameshift mutation and nonsense mutations associated with nonsense-mediated mRNA. It carries the advantage of fast screening of genes on the entire X chromosome without the need for large pedigree. Specifically we will (1) use XCM to screen 120 lymphoblast cell lines from XLMR males to identify novel candidate genes (2) identify responsible genetic defects by sequencing of the novel candidate genes in proband and in a large collection of XLMR males (3) functional studies of 4-6 novel XLMR genes to understand their physiological roles in human cognition and how mutations in these gene cause mental retardation. Results of the study will help to advance our knowledge on the genetic causes of mental retardation and to develop rational strategies for diagnosis, genetic counseling, prevention, and clinical care of patients with impairment of cognitive function.