Gyrate Atrophy of The Choroid and Retina

1. 线粒体酶的普遍缺乏。鸟氨酸转氨酶（OAT: EC 2.6.1.13）是旋转萎缩症（GA）的标志，这是一种导致失明的眼睛脉络膜和视网膜的遗传性退行性疾病。以本实验室已构建并鉴定的人OAT cDNA和抗人OAT抗体为探针，检测GA患者的OAT基因、mRNA和蛋白。对14例GA患者的基因组dna、rna和蛋白质进行印迹分析，发现1例功能OTA基因部分杂合缺失，未检测到OAT mRNA， OAT抗体反应蛋白水平几乎无法检测到。其余病例显示OAT基因、mRNA大体正常，OAT蛋白水平不同程度地降低。然后，我们更精确地分析了另一种遗传算法。南方分析表明功能基因大致完整。Northern分析显示，他的OAT mRNA仅为正常水平的一半，表明OAT基因的两个等位基因中只有一个表达更多。通过体外翻译和抗人OAT抗体免疫沉淀对表达的OAT mRNA进行功能分析表明，该信息合成了OAT蛋白。对表达的信息进行了克隆和测序，结果表明，在翻译的OAT蛋白的319位，包含一个从C到T的碱基变化，导致一个氨基酸密码子从CAT（组氨酸）变为TAT（酪氨酸）。突变体前体在体外线粒体运输/加工系统中进行了测试。结果表明，来自回旋萎缩患者的突变OAT前体可以被运输到线粒体，但在线粒体中加工的很少。我们用免疫细胞化学方法在人眼组织中定位鸟氨酸转氨酶。在视网膜中，神经节细胞和一些无突细胞具有免疫反应性。色素颗粒使得虹膜、睫状体色素上皮、脉络膜和视网膜色素上皮中的免疫反应产物难以识别。我们的研究结果表明，鸟氨酸转氨酶在这些眼部组织的鸟氨酸代谢中起重要作用。少

1. A generalized deficiency in the mitochondrial enzyme. Ornithine aminotransferase (OAT : EC 2.6.1.13), is the hallmark of gyrate atrophy (GA), a hereditary degenerative disease of the choroid and retina of the eye that leads to blindness. A human OAT cDNA, previously constructed and characterized in our laboratory, and anti-human OAT antibody were used as probes to examine the OAT gene, mRNA and protein of GA patients. A blot analysis of the genomic DNAs, RNAs, and proteins of 14 GA patients identified a case with a partial heterozygous deletion of the functional OTA gene, no detectable OAT mRNA, and a barely detectable level of OAT antibody-reactive protein. The rest of the cases showed grossly normal OAT gene, mRNA, and variably reduced levels of OAT protein.2. We then analyzed another case of GA more precisely. Southern analysis indicated the functional gene to be grossly intact. Northern analysis of his OAT mRNA demonstrated only half the normal level of OAT message, suggesting e … More xpression of only one of the two alleles of the OAT gene. A functional assay of the expressed OAT mRNA by in vitro translation and immunoprecipitation with antihuman OAT antibody indicated synthesis of an OAT protein from the message. The expressed message was cloned and sequenced and was shown to contain a single base change from C to T, resulting in an amino acid codon change from CAT (histidine) to TAT (tyrosine) at position 319 in the translated OAT protein. The mutant precursors were tested in an in vitro mitochondrial transport/ processing system. The results indicate that the mutant OAT precursor from the gyrate atrophy patient can be transported to the mitochondria but is minimally processed there.3. We localized ornithine aminotransferase in human ocular tissues using immunocytochemical procedures. In the retina, ganglion cells and some amacrine cells were immunoreactive. Pigmented granules made it difficult to identify immunoreactive products in the iris, pigmented epithelium of the ciliary body, choroid, and retinal pigment epithelium. Our findings suggested that ornithine aminotransferase plays an important role in ornithine metabolism in these ocular tissues. Less