Identifizierung von Kandidaten-Genen altersabhängiger Makuladegeneration (AMD) und familiärer Formen von Netzhauterkrankungen (Identification of candidate genes for age-related macular degeneration (AMD) and familial forms of retinal dystrophies)

在过去的几年里，分子遗传学研究揭示了一些单基因形式的黄斑营养不良的基因缺陷。然而，老年性黄斑变性(AMD)患者没有显示出这些基因与疾病相关的突变。识别AMD遗传危险因素的另一种方法是分析在视网膜、视网膜色素上皮(RPE)和/或脉络膜中特异表达的候选基因，或者在这些组织中具有重要功能的候选基因。在这里，我们建议识别和表征新的，眼睛特异的基因转录本，这些转录本是由于视网膜和邻近组织的退化和增殖过程而差异表达的。眼睛组织将从通过诺里病(ND)基因打靶建立的突变小鼠系中获得。对眼睛的形态分析显示，受影响动物的视网膜出现了特征性的变化，主要是在神经节细胞和包含中间神经元的内核层。光感受器细胞仅显示局灶性异常。差异表达基因将通过基因消减方案分离，并根据消减的方向分为两组：1.在变性视网膜中下调或消除的转录本；2.因组织损伤或细胞增殖而大量表达的mRNAs。这些老鼠基因的人类同源基因将被识别并定位在基因组中，并将被分析为AMD和家族性视力缺陷的候选基因。

During the last years, molecular genetic studies unraveled a number of gene defects underlying monogenic forms of macular dystrophies. However, patients with age-related macular degeneration (AMD) did not show disease-associated mutations these genes. A different approach to identify genetic risk factors for AMD represents the analysis of candidate genes which are either specifically expresed in the retina, retinal pigment epithelium (RPE), and/or choroid, or have an important function in these tissues. Here we propose to identify and characterize novel, eye-specific gene transcripts, which are differentially expressed as a result of degenerative and proliferative processes in the retina and adjacent tissues. Eye-tissues will be obtained from a mutant mouse line which was established by gene targeting of the Norrie disease (ND) gene. Morphological analysis of the eyes showed characteristic changes in the retina of affected animals, predominantly in ganglion cells and the inner nuclear layer which contains the intermediate neurons. The photoreceptor cells show only focal abnormalities. Differentially expressed genes will be isolated by a gene subtraction protocol and classified in two groups, depending on the orientation of the subtraction: 1. transcripts which are downregulated or eliminated in the degeneration retina and 2. those mrNAs which are abundantly expressed in response to tissue damage or as a result of cell proliferation. The human orthologues of these mouse genes will be identified, mapped in the genome and will be analyzed as candiate genes for AMD as well as familial forms of vision defects.