Molecular Genetics of X-linked Cataracts

描述(申请人提供)：先天性白内障，临床诊断 由于出生时白内障的存在，是基因突变的结果 这是适当的镜片发展所必需的。这样做的主要目标是 建议确定人类X连锁白内障中存在缺陷的基因 牙科(XLCD)综合征，一种与 小角膜和牙齿畸形。根据X上的表型和位置 XCAT小鼠是人类XLCD最好的动物模型。我们有 通过种间回交定位定位了xCAT，并鉴定了两个 标记Dx Was3 I和DxPas18没有与xCAT重组。酵母菌 人工染色体(YAC)和细菌人工染色体(BAC)文库 我们用这些标记进行筛选，得到了一个900kb的xCAT重叠群图 临界区。XCAT关键区域将通过BAC进行细化 转基因互补实验，旨在确定单个BAC 含有xCAT基因。我们将获得该BAC的序列并对其进行分析 对于潜在的转录单位和EX候选xCAT基因将进行筛选 在镜头中表达，通过南方动物园的斑点和数据库搜索 跨物种保护。保守和表达的候选基因 将评估其在xCAT小鼠体内的表达情况。他们还将 评估XCAT基因的突变情况。突变体之间的相关性 XCAT基因和白内障的表型将通过靶向破坏来确认 XCAT基因在转基因动物中的表达。最后，正常的小鼠xCAT序列将是 用于克隆相应的正常人类基因。在确定了 正常的XLCD基因结构，将对XLCD患者进行检查以确定 如果xCAT人类同源基因中存在突变。XLCD基因的鉴定 将有助于我们理解晶状体中涉及的分子事件 发展。

DESCRIPTION (provided by applicant): Congenital cataracts, clinically defined as the presence of cataracts at birth, are the result of mutations in genes that are required for proper lens development. The primary objective of this proposal is to identify the gene defective in the human X-linked cataract dental (XLCD) syndrome, a type of congenital cataract associated with microcornea and dental anomalies. Based on phenotype and location on the X chromosome, the Xcat mouse is the best animal model for human XLCD. We have positionally mapped Xcat through an interspecific backcross and identified two markers Dx Was3 I and DxPas18 that show no recombination with Xcat. Yeast artificial chromosome (YAC) and bacterial artificial chromosome (BAC) libraries were screened with these markers to develop a 900kb contig map of the Xcat critical region. The Xcat critical region will be refined through BAC transgenic complementation experiments designed to identify a single BAC that contains the Xcat gene. We will obtain the sequence of this BAC and analyze it for potential transcription units and ex Candidate Xcat genes will be screened for expression in the lens and by Southern zoo blots and database searches for conservation across species. Candidate genes that are conserved and expressed in prenatal lens will be evaluated for expression in Xcat mice. They will also be evaluated for mutations in the Xcat cDNA. The correlation between the mutant Xcat gene and the cataract phenotype will be confirmed by targeted disruption of Xcat in transgenic animals. Finally, the normal mouse Xcat sequence will be used to clone the corresponding normal human gene. After determining the structure of the normal XLCD gene, XLCD patients will be examined to determine if mutations in the Xcat human homolog are present. Identifying the XLCD gene would contribute to our understanding of the molecular events involved in lens development.