Age-Related Macular Degeneration: Genetic Variations and Animal Model

年龄相关性黄斑变性（AMD）在全球老年人中引起不可逆的中央视力丧失。各种研究表明AMD有显著的遗传成分。目前的证据支持基因变异导致患病倾向的假设。2003年，我们启动了这个项目，招募了晚期AMD患者和年龄匹配的正常视网膜对照个体。迄今为止，已有476人入选，并收集了107例AMD组织病理学病例。我们继续分析来自澳大利亚蓝山眼科研究的835份DNA样本和来自美国AREDS项目的534份DNA样本，因为一些DNA样本已经用完了。我们比较了AMD和对照组之间候选基因内单核苷酸多态性（snp）的等位基因频率，然后通过体外和/或体内实验对这些snp进行了功能研究。通过这种方法，我们已经确定了AMD的遗传危险因素以及这些基因变异在疾病发病机制中的可能作用。基于上述方法获得的信息，2007年，我们产生了一种基因工程动物（DKO rd8背景小鼠的Ccl2/Cx3cr1双重缺陷）作为AMD模型。虽然在将小鼠模型中的发现转化为人类模型时必须始终保持谨慎，但DKO rd8的AMD样表型使该模型成为评估AMD潜在治疗方法的有用工具。

Age-related macular degeneration (AMD) causes irreversible central visual loss in the aged population worldwide. Various studies suggest that AMD has a significant genetic component. Current evidence supports the hypothesis that gene variation creates a predisposition to the disease. In 2003, we initiated this project by recruiting advanced AMD patients and age-matched control individuals with normal retinas. Up to date, 476 individuals have been enrolled and 107 histopathological cases with AMD have been collected. We continue to analyze parts of 835 DNA samples from the Blue Mountain Eye Study in Australia and 534 DNA samples from the AREDS project in USA because some DNA samples had been ran out. We have compared the allelic frequencies of single nucleotide polymorphisms (SNPs) within candidate genes between AMD and control subjects, followed by functional studies of these SNPs by in vitro and/or in vivo experiments. Through this approach, we have identified genetic risk factors of AMD and the possible roles of these gene variations in the pathogenesis of the disease. Based on the information obtained from the above approaches, a genetically engineered animal (Ccl2/Cx3cr1 double deficiencies on rd8 background mice, DKO rd8) was generated to act as an AMD model in 2007. While caution must always be taken in translating findings in mouse models to findings in humans, the AMD-like phenotype of DKO rd8 makes the model an useful tool for evaluating potential therapies for AMD. In FY2014, (1) we continue working with collaborators to use our DKO rd8 model to study disease pathogenesis and therapeutic options of AMD, by evaluating the roles of PEDF (collaboration with Dr. S. Patricia Becerra), anti-LRP6 antibody in wnt singaling pathway(collaboration with Drs. Jinxing Ma and Heping Xu); (2) we provided DKO rd8 retina for studying the microRNAs role in AMD (collaboration with Drs. Shusheng Wang and Mengqing Xiang); (3) we published the association study between RBD51B and AMD in our cohorts; (4) a large scale SNP association study on the role of FBN2 in AMD was published. A similar study on the role of SNPs in 3-UTR regions of various genes in AMD is ongoing; (4) Some subjects recruited in this protocol were screened for their AMD related genotypes and will be used in the iPS project in collaboration with Drs. Sheldon Miller and Kapil Bharti; (5) we performed in vitro studies with ARPE-19 cells, human fetal RPE cells (collaboration with Dr. Sheldon Miller), and mouse retinal stem cells (collaboration with Ting Xie); (6) In this period, we published a total of 14 original or review papers including the novel findings of FBN2 gene in AMD.