MOLECULAR BASIS OF INHERITED DEAFNESS

诺里病是一种X连锁隐性疾病， 听力损失，沿着失明和智力迟钝。基因 诺里氏病的缺陷，NDP，最近已被确定， 我们的小组在马萨诸塞州总医院， 与英国的一个团体合作。这个基因编码norrin，a 蛋白质的15 kDa的预测大小，它具有部分同源性， 粘蛋白是一类高度糖基化的分泌蛋白。知识 缺陷蛋白质的序列将使我们能够确定其 听力正常的作用，以及缺陷如何有助于病因学， 诺里氏病norrin抗血清的初步结果表明 这种蛋白质是顶盖膜的组成部分， 声音刺激的受体细胞，突变可能会 导致盖膜薄弱或缺失。 我们建议确定norrin在内耳中的细胞分布， 通过原位杂交来确定制造它的细胞， 免疫细胞化学定位其最终位置。 我们将确定其 微解剖耳蜗凝胶电泳分子量测定 结构，我们将研究其糖基化的程度和性质， n. 我们还将评估诺里氏病听力损失的性质。诺莉 疾病患者将接受全面的听力测试， 他们听力缺陷的确切性质，以及他们携带的突变 将确定特定突变与病理学的相关性。我们希望 从患有诺里氏病的流产胎儿或尸检中获取材料 内耳组织病理学研究的材料。 为了建立进一步研究的动物模型，我们将制作一个转基因的 缺少norrin基因的小鼠。这些老鼠将进行听力学研究 诱发电位和耳声发射，他们的内耳 将进行组织学研究。 听力开始的相关性 形态学改变的缺陷将有助于了解 这种疾病如果在转基因动物中真的没有盖膜， 这些小鼠也将是一个有用的工具，以了解代 耳声发射最后，遗传性疾病最终将成为 通过某种形式的基因转移来治疗一种遗传性 耳聋以后将成为设计基因疗法的基础。

Norrie disease is an X-linked recessive disorder that causes a progressive hearing loss, along with blindness and mental retardation. The gene defective in Norrie disease, NDP, has recently been identified by positional cloning by our group at Massachusetts General Hospital, in collaboration with a group in England. The gene codes for norrin, a protein of 15 kDa predicted size, which has partial homology to the mucins, a family of highly g1ycosylated, secreted proteins. Knowledge of the sequence of the defective protein will enable us to determine its normal role in hearing, and how the defect contributes to the etiology of Norrie disease. Preliminary results with an antiserum to norrin suggests that the protein is a constituent of the tectorial membrane, which conveys the acoustic stimulus to the receptor cells, and that mutations might cause a weak or absent tectorial membrane. We propose to define the cellular distribution of norrin in the inner ear, by in situ hybridization to determine the cells that make it and by immunocytochemistry to locate its final position. We will determine its molecular weights vivo by gel electrophoresis of micro-dissected cochlear structures, and we will investigate the extent and nature of its glycosylat n. We will also evaluate the nature of hearing loss in Norrie disease. Norrie disease patients will be given complete audiological testing to understand the exact nature of their hearing deficit, and the mutation they carry will be determined to correlate specific mutations with pathology. We hope to obtain material from aborted fetuses with Norrie disease or autopsy material to study the histological pathology of the inner ear. To create an animal model for further study, we will make a transgenic mouse lacking the norrin gene. These mice will be studied audiologically with evoked potentials and otoacoustic emissions, and their inner ears will be studied histologically. Correlation of the onset of the hearing deficit with changes in morphology will help understand the etiology of the disease. If the tectorial membrane is in fact absent in transgenics, these mice will also be a useful tool to understand generation of otoacoustic emissions. Finally, inherited diseases will ultimately be treated by some form of gene transfer. A mouse model for an inherited deafness will later serve as a basis for designing gene therapy.