MOLECULAR DEFECT IN GYRATE ATROPHY OF CHOROID AND RETINA

脉络膜和视网膜回旋萎缩的分子缺陷

• 批准号: 3260890
• 负责人: VIVIAN E SHIH
• 金额: $ 14.92万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1984
• 资助国家: 美国
• 起止时间: 1984-12-01 至 1992-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3260890
• 关键词: DNA; affinity chromatography; alleles; aminoacid; autosomal recessive trait; biological polymorphism; chromosome disorders; electrophoresis; fibroblasts; genetic library; genetic mapping; genetic markers; genome; human tissue; lymphoblast; messenger RNA; mitochondria; molecular cloning; molecular pathology; mutant; nucleic acid sequence; ornithine oxoacid transaminase; ornithinemia; pyridoxine; radioassay; restriction mapping; structural genes; tissue /cell culture; vitamin therapy

Gyrate atrophy of the choroid and retina (GA) is an autosomal recessive chorioretinal degeneration, characterized by night blindness in childhood and progressive loss of peripheral vision leading to blindness in the 4th or 5th decades. Affected patients have marked hyperornithinemia due to deficient activity of ornithine aminotransferase (OAT or OKT). OAT is a major catabolic enzyme for ornithine and requires pyridoxine (Vitamin B6) as a cofactor. Based on the results of vitamin B6 therapeutic trials and in vitro OAT assays, the majority of GA patients are classified as B6 nonresponsive while a few patients are B6 responsive. Many fibroblasts and/or lymphoblasts from GA patients of both types and from obligate heterozygotes are available for molecular investigation of the primary defect. The structural gene for OAT has been mapped to chromosome 10 and OAT related sequences are present on the X chromosome. Restriction fragment length polymorphisms at the OAT locus will be used to haplotype the defective alleles associated with GA. The data will aid in prenatal diagnosis and carrier detection of GA, but more importantly, will lay the groundwork for isolation and characterization of several independent mutant OAT alleles. cDNAs prepared using mRNA from representative GA lines will be characterized by sequencing and compared with the normal gene to identify the mutation. For GA cell lines that show absence of OAT mRNA or an abnormal DNA pattern, genomic clones will be isolated and characterized to locate the primary defect by comparison to structure of the normal OAT gene and by functional studies. Mutations in the leader peptide affecting the transport of OAT precursor into the mitochondria and the role of leader peptide in the transport will also be explored. The OAT cDNA will be expressed in cells deficient in OAT activity. The proposed studies should yield a detailed understanding of the various genetric defects that may cause GA. The information gained will be clinical application in the diagnosis of GA, in identification of carriers of the defective OAT allele for purposes of family counselling, and possibly in treatment of the disorder.

脉络膜和视网膜回旋萎缩（GA）是一种常染色体遗传病 隐性脉络膜视网膜变性，以夜间为特征 儿童期失明并逐渐丧失周边视力 导致第四或第五个十年失明。 受影响的患者 由于缺乏鸟氨酸活性而有明显的高鸟氨酸血症 鸟氨酸转氨酶（OAT 或 OKT）。 OAT是一个主要 鸟氨酸的分解代谢酶，需要吡哆醇（维生素 B6) 作为辅助因子。 基于维生素 B6 治疗的结果 试验和体外 OAT 测定，大多数 GA 患者 分类为 B6 无反应，少数患者为 B6 反应灵敏。 许多来自 GA 的成纤维细胞和/或淋巴母细胞 这两种类型和来自专性杂合子的患者是 可用于主要缺陷的分子研究。 这 OAT 的结构基因已被定位到 10 号染色体 OAT 相关序列存在于 X 染色体上。 OAT 位点的限制性片段长度多态性 用于对与 GA 相关的缺陷等位基因进行单倍型分析。 这些数据将有助于产前诊断和携带者检测 但更重要的是，GA 将为隔离奠定基础 以及几个独立的突变型 OAT 等位基因的表征。 使用来自代表性 GA 系的 mRNA 制备的 cDNA 将 通过测序来表征并与正常情况进行比较 基因来识别突变。 对于显示的 GA 细胞系 缺乏 OAT mRNA 或异常 DNA 模式、基因组 将分离并表征克隆以定位主要克隆 通过与正常 OAT 基因的结构比较，发现缺陷 功能研究。 影响前导肽的突变 OAT 前体转运至线粒体的作用及其作用 运输中的前导肽也将被探索。 燕麦 cDNA 将在缺乏 OAT 活性的细胞中表达。 这 拟议的研究应详细了解 各种可能导致GA的遗传缺陷。 信息 所得成果将在 GA 诊断中得到临床应用 出于目的鉴定缺陷 OAT 等位基因的携带者 家庭咨询，并可能治疗这种疾病。