Cloning/Gene/Posterior Polymorphous corneal dystrophy

描述（由申请人提供）：后多形性角膜营养不良（PPCD， PPMD， PPD; OMIM # 122000）是一种主要的遗传性角膜内皮疾病，与广泛的临床特征和病程相关，从良性到重度视力丧失，伴有或不伴有青光眼，约15%的患者发生。PPCD被定位到染色体20p11-q11上，在theta = 0.0时观察到的最大LOD评分为5.54，标记为D20S45。对同一大家族21例患者中4例的重组事件分析显示，PPCD基因位于标记D20S98和D20S108之间的30 cM区域。本提案的目的是鉴定和表征负责PPCD的基因。这将实现如下：1。更好地定义PPCD的最小候选基因组区域。在先前确定的和额外的新家族中进行连锁分析，以继续精细绘制疾病位点，缩小候选区域，从而缩小PPCD的候选基因数量。检查20号染色体候选基因区域缺失的患者PPCD的临床特征，从而排除疾病间隔受影响部分的候选基因。2. 选择和优先考虑候选基因。确定哪些基因在成人角膜内皮中表达。微阵列分析（正常角膜内皮，PPCD患者角膜内皮）。基因表达序列分析（SAGE）。确定在角膜内皮中被发现表达的哪些基因映射到候选基因区域（定位方法）。分析定位于确定候选区间的基因的功能，选择那些可能在突变时导致PPCD中所见的临床和组织病理学异常的基因（功能方法）。3. 进行候选基因筛选。鉴定候选基因的序列变异。确定确定的序列变异是多态性还是突变。发现PPCD的遗传基础将为区分PPCD与其他具有重叠临床特征的疾病提供明确的方法，并确定青光眼导致视力丧失的风险增加的人群，同时为青光眼的发展机制提供更好的理解。此外，对该基因的操作可以使研究人员在体内或体外诱导角膜内皮细胞的可控增殖，为角膜内皮细胞数量不足以维持角膜清晰度的患者提供角膜移植的替代方案，这是世界范围内角膜移植最常见的适应症之一。

DESCRIPTION (provided by applicant): Posterior polymorphous corneal dystrophy (PPCD, PPMD, PPD; OMIM # 122000) is a dominantly inherited disorder of the corneal endothelium that is associated with a wide spectrum of clinical features and courses ranging from benign to profound visual loss from corneal swelling with or without associated glaucoma, which develops in approximately 15% of patients. PPCD has been mapped to chromosome 20p11-q11 with a maximum observed LOD score of 5.54 at theta = 0.0 with marker D20S45. Analysis of recombination events in 4 of the 21 affected patients in a single large family revealed that the PPCD gene is located in the 30 cM region between markers D20S98 and D20S108. The objective of this proposal is to identify and characterize the gene(s) responsible for PPCD. This will be accomplished as follows: 1. Better define the minimal candidate genomic region for PPCD. Perform linkage analysis in previously identified and additional new families to continue to fine map the disease locus, narrowing the candidate region, and therefore the number of candidate genes for PPCD. Examine patients with deletions in the candidate gene region of chromosome 20 for clinical features of PPCD, thereby ruling in or out candidate genes in the affected portion of the disease interval. 2. Select and prioritize candidate genes. Determine which genes are expressed in the adult human corneal endothelium. Microarray analyses (normal corneal endothelium, corneal endothelium in PPCD). Serial analysis of gene expression (SAGE). Determine which of the genes found to be expressed in the corneal endothelium map to the candidate gene region (positional approach). Analyze the function of the genes that map to the defined candidate interval, selecting those that may, when mutated, result in the clinical and histopathologic abnormalities seen in PPCD (functional approach). 3. Perform candidate gene screening. Identify sequence variants in the candidate genes. Determine whether identified sequence variants are polymorphisms or mutations. Discovery of the genetic basis of PPCD will provide a definitive means to distinguish it from other conditions with overlapping clinical features and to identify those at increased risk for vision loss from glaucoma as well as provide a greater understanding of the mechanisms of glaucoma development. Additionally, manipulation of this gene may allow researchers to induce the controlled proliferation of corneal endothelial cells in vivo or in vitro, providing an alternative to corneal transplantation for patients with an insufficient number of corneal endothelial cells to maintain corneal clarity, one of the most common indications for corneal transplantation worldwide.